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Kukulka, Wojciech, Krzysztof Cendrowski, Beata Michalkiewicz und Ewa Mijowska. „Correction: MOF-5 derived carbon as material for CO2 adsorption“. RSC Advances 9, Nr. 59 (2019): 34349. http://dx.doi.org/10.1039/c9ra90077b.
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Li, Yu, Chong Meng, Meng Wang, Bing Chuan Cheng und Chang Zhi Zhou. „Regulation of the Absorption of Cu with Various of Pollutants in Sediment through Fractional Factorial Design“. Advanced Materials Research 742 (August 2013): 363–66. http://dx.doi.org/10.4028/www.scientific.net/amr.742.363.
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The resolution IV fractional factorial design was used to study the adsorption regularity of Cu coexisted with various pollutions (Zn, Pb, Cd, Ni, atrazine, malathine, et al.) onto the sediment. The study found that the main effect and the second-order interaction effect of ten pollutions concentration had significant influence on the adsorption of Cu on the sediment. The concentration of Cu was the critical factor to the promotion of the absorption capacity of Cu in sediment, the second-order effect played the critical role in restraining the absorption of Cu. The main effect of Cd, and the second-order interaction effect include Cd, had greatly inhibited the absorption of Cu in sediment, and the contribution was over 30%, which meant there was prominent antagonism between Cu and Cd. Fractional factorial design can provide a theoretical basis for the reveal of the adsorption mechanism between the different contaminants in the water environment pollution.
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Sadeghi, A. A., A. Nikkhah und P. Shawrang. „The effect of thermally activated natural zeolite on colostral IgGl, IgM and Aga absorption in newborn Holstein calves“. Proceedings of the British Society of Animal Science 2005 (2005): 210. http://dx.doi.org/10.1017/s1752756200011212.
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Neonatal calves are born with no immunoglobulins (Igs) in the blood stream and rely on Ig from colostrum through passive immunity transfer. Unfortunately, transfer of passive immunity to neonatal calves is too often inadequate, resulting in excessive rates of morbidity and mortality. Natural zeolite is characterized by framework of linked tetra hydration enclosing open cavities in the form of channels, and cages with ion exchanger and adsorption capacity. In literature, there were reported that thermally activated natural zeolite (T-zeolite) could increase colostral IgG absorption and decrease susceptibility of neonates to infections (Sadeghi et al., 2004; Stojic et al., 1995). To our knowledge, little information is available concerning the effect of thermally activated natural zeolite on colostral IgG1, IgM and IgA absorption in neonates. Our experiment was designed to investigate the effect of thermally activated natural zeolite on colostral IgG1, IgM and IgA absorption in newborn Holstein calves.
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Cao, Weijie, Tomoki Uchiyama, Kentaro Yamamoto, Toshiyuki Matsunaga, Toshiharu Teranishi, Ryota Sato, Hideto Imai, Yoshiharu Sakurai, Yoichiro Tsuji und Yoshiharu Uchimoto. „Operando X-Ray Absorption Spectroscopic Study on Influence of Specific Adsorption of Sulfo Group in Perfluorosulfonic Acid Ionomer Towards ORR Activity of Pt/C Catalyst“. ECS Meeting Abstracts MA2022-02, Nr. 42 (09.10.2022): 1559. http://dx.doi.org/10.1149/ma2022-02421559mtgabs.
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Polymer electrolyte fuel cells (PEFCs) are clean energy devices with polymer electrolytes and are expected to play an important role in the development of a global renewable energy system and a pure hydrogen energy society in the future. PEFCs have already been applied for small-scale energy systems such as fuel cell vehicles (FCVs). Pt-based catalysts are basically used due to the relatively inefficient reaction kinetics and catalyst degradation under strong acidic conditions during the oxygen reduction reaction (ORR). However, there are still many difficulties in realizing acceptable cost-effective FCVs. It is known that the ORR activity of Pt-based catalysts is reduced by specific adsorption of anionic species. Perfluorosulfonic acid ionomers such as Nafion® are commonly included in the catalyst layers of PEFCs to provide protonic pathways for promoting the ORR1. However, direct observation of anion adsorption on practical Pt nanoparticle/C catalysts for perfluorosulfonic acid ionomers using X-ray absorption spectroscopy (XAS) still has less report. In this study, to achieve specific adsorption over a higher potential range that is at least equal to the ORR active potential (around 0.90 V vs. RHE), operando XAS measurements were performed; the electronic status and local structural change of Pt atoms induced by the specific adsorption of anions at any potential were observed2. Pt/C (29.1 wt.%; TEC10V30E) catalyst supported was purchased from TKK. Nafion® solution was employed to prepare Pt/C catalyst ink with I/C ranging from 0.0 to 1.0. And the amount of Pt/C was adjusted to form a 20 µgcarbon cm-2 catalyst layer after dropping 10 μL on a glassy carbon RDE. The electrochemical cell was constructed using a model electrode fabricated in the working electrode, a Pt mesh for the counter electrode, a reversible hydrogen electrode for the reference electrode, and 0.1 M HClO4 aq for the electrolyte. operando XAS measurement of Pt L-edge was carried out in SPring-8 (Japan). The specific activity decreased as the I/C ratio increased from 0.0 to 0.20. We utilized many methods to evaluate the adsorption species separately, including the measurements of ECSA and oxygen coverage, CO stripping voltammetry, operando X-ray absorption fine structure, and analysis of 5d orbital vacancy. The ECSA and oxygen coverage did not change with increasing ionomer content, indicating that the Pt/C catalyst activity was affected by other adsorption species. A comparison of the CO displacement charge and 5d orbital vacancies of the Pt/C catalysts with I/C = 0.0 and 1.0 suggests that the ionomer-specific adsorption increases when the I/C ratio of the Pt/C catalyst is 1.0; active sites on the surface of the Pt/C catalyst are occupied, resulting in lower catalyst activity. Acknowledgment This work was supported by the project (JPNP20003) and a NEDO FC-Platform project commissioned by the New Energy and Industrial Technology Development Organization (NEDO). References: [1] Subbaraman, R.; Strmcnik, D.; Markovic, N. M.; et al. J. Chem. Phys. Phys. Chem. 2010, 11, 13, 2825-2833. [2] Liu, C.; Uchiyama, T.; Uchimoto, Y.; et al. ACS Appl. Energy Mater. 2021, 4 (2), 1143-1149. Figure 1
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Espinosa-Garza, Gerardo, Imelda de Jesús Loera-Hernández und Edgardo Jorge Escalante Vázquez. „Elimination of Hg (II) in Water by Adsorption through Banana“. Key Engineering Materials 931 (09.09.2022): 139–49. http://dx.doi.org/10.4028/p-7t5808.
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Banana peel is a low-cost resource that can be used in a wide range of chemical and industrial processes. The novelty of this research is the use of dehydrated and sieved banana peel to remove mercury from water. The main objective of this research is to evaluate the capacity of the banana peel as an adsorbent capable of removing mercury from contaminated water. It has been shown to be an efficient, low-cost, and environmentally friendly process because banana peel is an environmental waste. To determine the ability of the banana peel to adsorb mercury, the following variables were considered: Hg concentration in water (10, 20, 30, 40, 50, 60, 70, 80, 90 and 100 ppb), particle size of the banana peel (100, 150, 200, 250 and 300 microns), quantity of banana peel per 125 ml of solution contaminated with Hg (2 and 5 grams), the contact time was (20, 40 and 60 minutes); it was not necessary to modify the pH of the solutions to obtain high % of mercury removal. The minerals and fatty acids present in the banana peel were also analyzed to improve the interpretation of the adsorption results. A higher adsorption capacity of mercury was perceived with a banana peel sieved at 150 microns; the results are consistent with other research works such as Cd (II) adsorption according to Azarpira et al. [1] where absorption is improved by decreasing the particle size of the filter material. The effectiveness of bioadsorption depends on the initial concentration of mercury ions and the filter material, the particle size of the filter material, the contact time between the mercury ions and the filter material and the pH (although in this project it is not this variable has been intervened). This study demonstrates that the banana peel used as an adsorbent is very efficient and inexpensive for removing mercury from wastewater. It became possible to demonstrate that the amount of Hg adsorbed per unit mass of absorbent increases with increasing initial Hg concentration in contaminated water, as in other metals [1]. The results of this study have confirmed the viability of using banana peel as an effective alternative for removing mercury from mercury-contaminated waters. Future studies will help to evaluate the economic use of this bioadsorbent and the identification of the main active elements it possesses in mercury adsorption. This study will allow a deeper understanding of the mercury absorption process and will verify the potential possibilities of methods to improve the adsorption process.
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Motakef kazemi, Negar. „Zinc based metal–organic framework for nickel adsorption in water and wastewater samples by ultrasound assisted-dispersive-micro solid phase extraction coupled to electrothermal atomic absorption spectrometry“. Analytical Methods in Environmental Chemistry Journal 3, Nr. 04 (29.12.2020): 5–16. http://dx.doi.org/10.24200/amecj.v3.i04.123.
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In this research, Zn2(BDC)2(DABCO) metal–organic framework (MOF) as a solid phase was used for separation and preconcentration toxic nickel ions (Ni) from water samples by ultrasound assisted-dispersive-micro solid phase extraction coupled to electrothermal atomic absorption spectrometry (USA-D-μ-SPE/ET-AAS). The MOF nanostructure was characterized by field emission-scanning electron microscope (FE-SEM) and transmission electron microscopey (TEM) for presentation of morphology and size of MOF synthesis. By procedure, 25 mg of Zn2(BDC)2(DABCO) as MOF adsorbent was added to 25 mL of water samples and then, Ni ions chemically adsorbed based on dative bonding of nitrogen in DABCO (1,4-diazabicyclo [2.2. 2]octane); N2(C2H4)3) at pH=8. The adsorbent was separated from liquid phase by syringe cellulose acetate filters (SCAF, 0.2 μm) and Ni ions back extracted from MOF adsorbent before determined by ET-AAS. The maximum recovery of MOF for nickel ions as a physically and chemically adsorption was obtained 34.6% and 98.8% at pH=3 and 8, respectively.
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Doan, Huong, Ricardo Sgarbi, Quentin Labarde und Marian Chatenet. „The Positive Effects of Carbon-Coating Layers on Protecting the Nanoparticle Towards Poisoning Ions or Gases“. ECS Meeting Abstracts MA2023-02, Nr. 41 (22.12.2023): 2030. http://dx.doi.org/10.1149/ma2023-02412030mtgabs.
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Recently, the research that explores the positive effects of carbon-coating nanoparticles to fight the severe oxidation/corrosion in Alkaline fuel cell (AFC), Proton-exchange membrane fuel cell (PEMFC) or water electrolyzer is well-recognized, since the carbon layers can extend the catalyst’s durability towards hydrogen oxidation/evolution reactions (HOR, HER) and oxygen evolution/reduction reactions (OER, ORR). Especially for the reactions in alkaline pH, with the graphite coating, the Ni nanoparticles in both HOR and HER can resist passivation and hydride poisoning. [1,2] Similarly, in the same alkaline conditions, the amorphous carbon coating slows down the degradation of Pd catalysts.[3] Moreover, the coating can block big ions such as halide, thus benefiting Pt group metals from resisting halide adsorption, that eventually prevents the dissolution of metal.[4,5] In this work, we examined the gas poisoning effects on coated catalysts. For example, we synthesized carbon-coated Pd-Ni nanoparticles, supported on Vulcan carbon and studied its electrochemical response in 0.1M KOH at room temperature and its tolerance towards CO gas. As a result, Pd-Ni coated had better resistance to passivation compared to the non-coated Pd-Ni catalyst. It also showed that the thickness of the carbon coating layers was sufficient to block the CO absorption in RDE condition initially (Figure 1, black solid line). Only after 150 cycles of accelerated stress test in Ar (AST-Ar, using potential stepping between 0.1 and 1.23 V vs. RHE with a pulse of 3 s at each potential in Ar-saturated electrolyte, 6s/cycles), the passivation that occurred at high potential could cause a small portion of Pd to be “exposed” and adsorb CO (Figure 1, red solid line). After another 150 cycles of AST-Ar (AST 300), more Pd was exposed to CO adsorption but not fully. This proves the carbon-coating layers can protect the nanoparticles from poison contaminant gas such as NOx, SOx, CO, or the COx-like species. Both AFC and PEMFC systems can benefit from this type of catalyst to operate extensively without losing catalytic activity to passivation or pollution issues. References [1] Gao, Y. et al. ACS Appl. Mater. Interfaces 2020, 12 (28), 31575–31581. [2] Doan, H. et al. J. Electrochem. Soc. 2021 168 084501 [3]Sgarbi, R., Doan, H. et al. Electrocatalysis 2022. [4] Lin, G. et al. J. Electrochem. Soc. 2016, 163 (1), A5049–A5056. [5] Mukerjee, S., Doan ,H. et al. - US Patent 10,784,518, 2020 Figure 1
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Rakhtshah, Jamshid. „Separation and determination of cadmium in water samples based on functionalized carbon nanotube by syringe filter membrane- micro solid-phase extraction“. Analytical Methods in Environmental Chemistry Journal 4, Nr. 01 (28.03.2021): 5–15. http://dx.doi.org/10.24200/amecj.v4.i01.132.
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A simple and fast separation of cadmium (Cd) based on functionalized carbon nanotubes with 2,3-dimercapto-1-propanol (CNTs@DHSP) was achieved in water samples before a determination by atom trap flame atomic absorption spectrometry (AT-FAAS). In this study, Cd(II) ions were extracted by syringe filter membrane-micro solid phase extraction procedure(SFM-μ-SPE). Firstly, 20 mg of the CNTs@DHSP as solid-phase added to 20 mL of water sample in a syringe, then dispersed for 3 min after adjusting pH up to 7 and pass through SFM very slowly. After extraction, the Cd(II) ions were back-extracted from SFM/CNTs@DHSP by 1.0 mL of eluent in acidic pH. Finally, the cadmium concentration was measured by AT-FAAS. Under the optimal conditions, the linear range (2–90 µg L−1), LOD (0.75 µg L−1) and enrichment factor (19.6) were obtained (RSD<1.5%). The adsorption capacity of Cd(II) with the CNTs@DHSP was obtained about 152.6 mg g-1. The method was validated by certified reference materials (SRM, NIST) and ET-AAS in water samples.
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Kralin, Vyacheslav, Anton Orekhov, Roman Kamyshinsky, Yury Chesnokov und Polina Demina. „Abstract P-35: Cryo-Electron Tomography of Protein Conjugated Upconverting Nanophosphors“. International Journal of Biomedicine 11, Suppl_1 (01.06.2021): S27. http://dx.doi.org/10.21103/ijbm.11.suppl_1.p35.
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Background: Over the past decades, significant advances have been made in the field of creating nanobioreagents for solving modern medicine problems (Grebenik et al., JBO, 2013). However, the problem of their low accumulation rate in pathological tissue in vivo experiments still remains. First of all, it is associated with the adsorption of blood proteins on the surface of nanobioreagents and the protein layer formation, which significantly changes the surface properties, which leads to their rapid excretion by the reticuloendothelial system. In particular, it is possible to reduce the blood plasma proteins adsorption and increase the time spent in the circulatory system by forming a coating of proteins. Methods: In situ cryоelectron tomography (Cryo-ET) is the only method that allows the experimental observation of protein structures on the nanoparticle’s surface in their natural functional state. The basic principle of the method is to obtain a series of projections of a vitrified sample thin lamella at different tilt angles related to an incident electron beam. Their further processing leads to obtaining the volumetric information about the structure of the sample. The use of a cryo-focused ion beam (Cryo-FIB) in specimen thinning makes it possible to carry out experiments with thin sections of cellular structures and observe the penetration of nanoparticles into the intracellular environment. Results: Upconverting nanophosphors (AN) were used as a nanoplatform for creating a protein coating. To create a protein coating on the AN surface, they were functionalized using an amphiphilic polymer containing carboxyl groups. Then, conjugation with protein molecules from the class of immunoglobulins was carried out by the method of carbodiimide activation. At each stage of synthesis and modification, AN solutions with different size distribution were vitrified for subsequent tomography. After a series of experiments to study the morphology of nanoparticles, an experiment on their successful absorption by cells of the cancer line A549 was carried out. Conclusion: Within this work, a series of in situ Cryo-ET methods were proposed and applied for structural characterization and visualization of the processes of synthesis, modification, and engulfment of nanoparticles into cellular systems. For the first time in its native form, the engulfment of ANF into the internal environment of the A549 cancer line cells was demonstrated.
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Schmid, O., P. Artaxo, W. P. Arnott, D. Chand, L. V. Gatti, G. P. Frank, A. Hoffer, M. Schnaiter und M. O. Andreae. „Spectral light absorption by ambient aerosols influenced by biomass burning in the Amazon Basin. I: Comparison and field calibration of absorption measurement techniques“. Atmospheric Chemistry and Physics 6, Nr. 11 (21.08.2006): 3443–62. http://dx.doi.org/10.5194/acp-6-3443-2006.
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Abstract. Spectral aerosol light absorption is an important parameter for the assessment of the radiation budget of the atmosphere. Although on-line measurement techniques for aerosol light absorption, such as the Aethalometer and the Particle Soot Absorption Photometer (PSAP), have been available for two decades, they are limited in accuracy and spectral resolution because of the need to deposit the aerosol on a filter substrate before measurement. Recently, a 7-wavelength (λ) Aethalometer became commercially available, which covers the visible (VIS) to near-infrared (NIR) spectral range (λ=450–950 nm), and laboratory calibration studies improved the degree of confidence in these measurement techniques. However, the applicability of the laboratory calibration factors to ambient conditions has not been investigated thoroughly yet. As part of the LBA-SMOCC (Large scale Biosphere atmosphere experiment in Amazonia – SMOke aerosols, Clouds, rainfall and Climate) campaign from September to November 2002 in the Amazon basin we performed an extensive field calibration of a 1-λ PSAP and a 7-λ Aethalometer utilizing a photoacoustic spectrometer (PAS, 532 nm) as reference device. Especially during the dry period of the campaign, the aerosol population was dominated by pyrogenic emissions. The most pronounced artifact of integrating-plate type attenuation techniques (e.g. Aethalometer, PSAP) is due to multiple scattering effects within the filter matrix. For the PSAP, we essentially confirmed the laboratory calibration factor by Bond et al. (1999). On the other hand, for the Aethalometer we found a multiple scattering enhancement of 5.23 (or 4.55, if corrected for aerosol scattering), which is significantly larger than the factors previously reported (~2) for laboratory calibrations. While the exact reason for this discrepancy is unknown, the available data from the present and previous studies suggest aerosol mixing (internal versus external) as a likely cause. For Amazonian aerosol, we found no absorption enhancement due to hygroscopic particle growth in the relative humidity (RH) range between 40% and 80%. However, a substantial bias in PSAP sensitivity that correlated with both RH and temperature (T) was observed for 20%<RH<30% and 24°C<T<26°C, respectively. In addition, both PSAP and Aethalometer demonstrated no sensitivity to gaseous adsorption. Although very similar in measurement principle, the PSAP and Aethalometer require markedly different correction factors, which is probably due to the different filter media used. Although on-site calibration of the PSAP and Aethalometer is advisable for best data quality, we recommend a set of "best practice" correction factors for ambient sampling based on the data from the present and previous studies. For this study, the estimated accuracies of the absorption coefficients determined by the PAS, PSAP and Aethalometer were 10, 15 and 20% (95% confidence level), respectively.
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Qiao, Yu, Brian Seger, Degenhart Hochfilzer, Bjørt Óladóttir Joensen, Wanyu Deng und Ib Chorkendorff. „(Digital Presentation) Investigations on the Ethanol/Ethylene Bifurcation and Restructure of Cu/Ag Catalysts for Electrochemical CO2 Reduction“. ECS Meeting Abstracts MA2022-01, Nr. 36 (07.07.2022): 1614. http://dx.doi.org/10.1149/ma2022-01361614mtgabs.
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Electrochemical CO2 reduction (ECO2R) converts greenhouse gas CO2 into valuable fuels and chemicals, and thus helps with closing the anthropogenic carbon cycle. Currently, Cu is the only known material being capable of producing a variety of hydrocarbons and alcohols, while the poor selectivity limits its further use. Ethanol and ethylene have been proved to go through similar pathways but their bifurcation is yet to be fully understood. It has been found that introducing Ag atoms into Cu lattice could shift the product distribution toward ethanol compared to ethylene. However, previous studies have proposed contradictory speculations: DFT calculations predict the introduced Ag atoms prefer to dope on the undercoordinated sites on Cu surface [1], while experiments have proved that C-C coupling occurs at these sites and is promoted when they are occupied by Ag [1]–[3]. Literature also interpreted various mechanisms of the interaction between Cu and, such as the constrained effect [1], [4], “spillover” [5], and different C-C coupling pathways between *CO and *CHx (x=1,2) at the boundaries [6]. The oxidation state [7] and faceting [1] as well as the composition of CuAg catalysts over time have been observed during the reaction course, but explicitly real-time information remains scarce. To provide more mechanistic information on the above controversies, we prepared both bimetallic (with miscible Cu and Ag phases s) and surface alloy (with separated Cu and Ag phases) CuAg thin films by physical vapor deposition (PVD) and galvanic exchange, respectively. Ex situ X-ray Photoelectron Spectroscopy (XPS) and O perando X-ray Absorption Spectroscopy (XAS), including X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) on surface alloy CuAg are performed under ECOR/ECO2R conditions to investigate the oxidation state and coordination numbers of Cu and Ag. By this means, electron transfer and the interface miscibility between Cu and Ag are identified. Combined with DFT calculations, we speculated possible doping sites of Ag atoms in the Cu lattice and potential adsorption sites of the produced intermediates for ethanol/ethylene formation. Besides, variations of the oxidation state, electric and geometric local structure, as well as the transformation in crystallinity of the CuAg catalysts over time are monitored by correlating XAS with operando Grazing Incidence X-ray Diffraction (GIXRD). The produced CO intermediates are substantiated to be the reason for Cu-enrichment occurring on the CuAg electrodes as speculated. References: [1] D. Higgins et al., “Guiding Electrochemical Carbon Dioxide Reduction toward Carbonyls Using Copper Silver Thin Films with Interphase Miscibility,” ACS Energy Lett., vol. 3, no. 12, pp. 2947–2955, 2018, doi: 10.1021/acsenergylett.8b01736. [2] L. Wang et al., “Selective reduction of CO to acetaldehyde with CuAg electrocatalysts,” Proc. Natl. Acad. Sci. U. S. A., vol. 117, no. 23, pp. 12572–12575, 2020, doi: 10.1073/pnas.1821683117. [3] C. Hahn et al., “Engineering Cu surfaces for the electrocatalytic conversion of CO2: Controlling selectivity toward oxygenates and hydrocarbons,” Proc. Natl. Acad. Sci. U. S. A., vol. 114, no. 23, pp. 5918–5923, 2017, doi: 10.1073/pnas.1618935114. [4] E. L. Clark, C. Hahn, T. F. Jaramillo, and A. T. Bell, “Electrochemical CO2 Reduction over Compressively Strained CuAg Surface Alloys with Enhanced Multi-Carbon Oxygenate Selectivity,” J. Am. Chem. Soc., vol. 139, no. 44, pp. 15848–15857, 2017, doi: 10.1021/jacs.7b08607. [5] S. Lee, G. Park, and J. Lee, “Importance of Ag-Cu Biphasic Boundaries for Selective Electrochemical Reduction of CO2 to Ethanol,” ACS Catal., vol. 7, no. 12, pp. 8594–8604, 2017, doi: 10.1021/acscatal.7b02822. [6] Y. C. Li et al., “Binding Site Diversity Promotes CO2 Electroreduction to Ethanol,” J. Am. Chem. Soc., vol. 141, no. 21, pp. 8584–8591, 2019, doi: 10.1021/jacs.9b02945. [7] S. B. Scott et al., “Absence of Oxidized Phases in Cu under CO Reduction Conditions,” ACS Energy Lett., vol. 4, no. 3, pp. 803–804, 2019, doi: 10.1021/acsenergylett.9b00172.
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Wibowo, Enggar, Raul Garcia-Diez, Tomas Bystron, Martin Prokop, Marianne van der Merwe, Mauricio D. Arce, Catalina Elena Jiménez et al. „Oxidation of Aqueous H3PO3 on Pt Studied By X-Ray Spectroscopies“. ECS Meeting Abstracts MA2022-02, Nr. 56 (09.10.2022): 2162. http://dx.doi.org/10.1149/ma2022-02562162mtgabs.
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High-temperature polymer electrolyte membrane fuel cells (HT-PEMFCs) employing a phosphoric acid H3PO4-doped membrane are considered to be promising sustainable electrochemical energy storage. The high-temperature operation has several advantages, such as a higher tolerance to CO poisoning, allowing coupling of HT-PEMFCs with reformers [1-3], as well the possibility for heat and electric energy co-generation [1,2]. However, during operation, phosphorus oxo-acids (e.g.: H3PO3) are generated on the anode. These impurities adsorb on the Pt catalyst [4-6], thus possibly negatively affecting the HT-PEMFCs performance. A detailed understanding of the H3PO3-catalyst (Pt) interaction is hence necessary for further HT-PEMFC optimization. However, besides an investigation of the H3PO3 adsorption behavior on Pt [6,7], literature on the behavior of the H3PO3 in contact with Pt (with/without polarization) is scarce. In this work, the oxidation mechanism of H3PO3 was investigated using a combination of in situ x-ray spectroscopy techniques that directly probe the H3PO3/Pt interface interaction, complemented by ex situ x-ray photoelectron spectroscopy (XPS) and ion-exchange chromatography (IEC). IEC gave insights into the effect of Pt on the stability of deaerated aqueous H3PO3 solutions. XPS was conducted on H3PO3/support structures (including Au and Pt supports) to determine to what extent the support affects the H3PO3 oxidation. Furthermore, in-situ dip and pull near-ambient pressure (NAP-)XPS was conducted to investigate the state of H3PO3 at the H3PO3/Pt interface and in solution bulk. It was observed that at the H3PO3/Pt interface, H3PO3 was chemically oxidized to H3PO4, while in the bulk solution it remains stable, as shown in Figure 1. Moreover, in situ x-ray absorption spectroscopy at the P K-edge was conducted at different concentrations of H3PO3 in aqueous solutions (i.e., different amounts of H2O) in contact with Pt, to determine the role of H2O in the oxidation of H3PO3. A higher degree of oxidation was observed for the less concentrated H3PO3, implying that H2O participates in the oxidation mechanism of H3PO3 to H3PO4. References: [1] Chandan et al., A.. J. Power Sources 2013, 231, 264–278. [2] Asensio, et al. Chem. Soc. Rev. 2010, 39 (8), 3210. [3] Q. Li et al, J. Electrochem. Soc. 2003, 150 (12), A1599. [4] Sugishima et al, J. Electrochem. Soc. 1994, 141 (12), 3332. [5] Doh et al. ChemElectroChem. 2014, 1 (1), 180–186. [6] Prokop et al, Electrochimica Acta 2015, 160, 214–218. [7] Prokop et al, Electrochimica Acta 2016, 212, 465–472. Figure 1
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Nakamura, Genki, und Hirohisa Tanaka. „Improvement of Oxygen Reduction Reaction Performance of Fe-N-C Catalyst“. ECS Meeting Abstracts MA2023-02, Nr. 49 (22.12.2023): 3332. http://dx.doi.org/10.1149/ma2023-02493332mtgabs.
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Fuel cells are gaining worldwide attention as an acceptable technology for achieving carbon neutrality. However, existing fuel cells use large amounts of precious metals, which limits their widespread adoption. Precious metal-free fuel cells have been studied in our laboratory. The oxidation-reduction reaction (ORR) at the cathode of the fuel cell must start at a higher potential and proceed smoothly in a four-electron reduction reaction without producing hydrogen peroxide1,2. We have synthesized iron-based complex catalysts using the method reported by Plamen Atanassov3 et al. Iron nitrate dihydrate is mixed in aqueous solution with glucose, 2-methylimidazole, and zinc nitrate hexahydrate, followed by hydrothermal synthesis at 200°C for 24 hours. It is then acid-treated with nitric acid to dissolve excess metallic iron, and the process is repeated twice at 950°C to complete the Fe-N-C catalyst. However, SEM and XRD analysis confirmed the presence of large amounts of metallic iron. In response to these results, the synthetic process of the Fe-N-C catalyst was repeatedly improved, and the prepared catalyst was subjected to in-situ XAFS (X-ray absorption fine structure) analysis using synchrotron radiation at SPring-8 (Fig. 1). The peak around 7110 eV is significantly different from that of metallic iron (Fe foil), indicating that iron complex, iron phthalocyanine (II), and it is like the peak of iron phthalocyanine (II), confirming that the prepared Fe-N-C catalyst forms a good complex. The performance of the Fe-N-C catalyst with the confirmed complexation was then investigated, and a cathode that exhibited ORR performance comparable to that of the Pt catalyst was successfully synthesized (Fig. 2). In the future, further improvement of the catalyst preparation process will be discussed to develop a catalyst with much better performance than Pt. Reference 1N. Yamamoto, D.Matsumura, Y. Hagihara, K.Tanaka, Y. Hasegawa, K. Ishii, H. Tanaka, “Investigation of hydrogen superoxide adsorption during ORR on Pt/C catalyst in acidic solution for PEFC by in-situ high energy resolution XAFS”, Jounal of Power Sources, 557, 15, (2023), 232508 2S. Kusano, D. Matsumura, K. Ishii, H. Tanaka, J. Mizuki, “Electrochemical Absorption on Pt Nanoparticles in alkaline Solution Observed Using in-situ High Energy Resolution X-ray Absorption Spectroscopy”, Nanomaterials, 9, 4, (2019), 642 3 R. Gokhale, L-K. Tsui, K. Roach, Y. Chen, M. M. Hossen, K. Artyushkova, F. Garzon, p. Atanassov, “Hydrothermal synthesis of platinum-Group-Metal-Free Catalysts: Structural Elucidation and Oxygen Reduction Catalysis”, ChemElectroChem, 5, 14, (2017), 1848-1853 Figure 1
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Baghaie, Amir Hossein, und Mehran Keshavarzi. „The Effect of Montmorillonite Nano-Clay on the Changes in Petroleum Hydrocarbon Degradation and Cd Concentration in Plants Grown in Cd-Polluted Soil“. Avicenna Journal of Environmental Health Engineering 5, Nr. 2 (29.12.2018): 100–105. http://dx.doi.org/10.15171/ajehe.2018.13.
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Contamination with heavy metals and petroleum hydrocarbons is considered as an environmental problem. Thus, this research was done to evaluate the effect of montmorillonite nano-clay on the changes in petroleum hydrocarbon degradation and cadmium (Cd) concentration in plant grown in a Cd-polluted soil. Treatments consisted of two levels of montmorillonite nano-clay (0 and 1% W/W) in a Cd-polluted soil (0, 5, 10 mg Cd/kg soil) and crude oil-polluted soil (0, 1 and 2% W/W). The plant used in this study was Tall Fescue (Festuca arundinacea L.). After 20 weeks, the concentration of Cd in plants was measured by atomic absorption spectroscopy and the total petroleum hydrocarbon (TPHs) in the soil was determined using the GC-mass spectrometry. Soil respiration was determined according to the method used by Qiao et al. ANOVA was used for statistical analysis of data. The least significant difference (LSD) test was used to determine the differences between the means. The application of 1% (w/w) montmorillonite nano-clay in Cd-polluted soil (10 mg Cd) without crude oil decreased Cd concentration in plant and increased microbial respiration by 18% and 34%, respectively. In addition, the application of 1% montmorillonite nano-clay in soil polluted with 1% crude oil and 10 mg Cd enhanced TPHs degradation by 27%. The use of montmorillonite nano-clay increased Cd adsorption in soil which resulted in an increase in microbial respiration and, hence the degradability of petroleum hydrocarbon in the soil.
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Endang Dewi Masithah, Khilyatun Nisak, Boedi Setya Rahardja,. „Studi Perbandingan Kemampuan Nannochloropsis sp. Dan Spirulina sp. Sebagai Agen Bioremediasi Terhadap Logam Berat Timbal (Pb) [Comparative Study Of Ability Nannochloropsis sp. And Spirulina sp. As Agent Bioremediation Of Heavy Metal Plumbum (Pb) ]“. Jurnal Ilmiah Perikanan dan Kelautan 5, Nr. 2 (19.01.2019): 175. http://dx.doi.org/10.20473/jipk.v5i2.11405.
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Abstract Microalgae species Nannochloropsis sp. can used as heavy metal biosorben because of it’s adsorption capability that caused by the active cluster which contained in that species (Sembiring et al., 2008). Chlorella sp. is one of phytoplankton species that has the bioaccumulation ability of heavy metals and easily cultivated (Arifin, 1997). Lead (Pb) is a mineral belonging to microelements, is a heavy metal and is a potentially toxic material. Water bodies that have been polluted by compounds or ions Pb because can lead to the death of aquatic biota, the number of Lead (Pb) present in water bodies exceeding the proper concentration (Palar, 2004). One way to anticipate the increasing heavy metal pollution in the water is to bioremediation. The research using experimentally, the research design used was completely randomized design (CRD) consisting of four treatments with five replications. The concentrations of heavy metals Plumbum (Pb) used is 0 ppm and 0.9 ppm. The main parameters in this study is the ability of bioremediation Plumbum (Pb) by Nannochloropsis sp. and Chlorella sp. SPSS analytics normality test results and test the ability of T 95% in Nannochloropsis sp. and Chlorella sp. in absorbing heavy metals Plumbum (Pb) concentrations of 0 ppm and 0.9 ppm indicate that the data is normal and the results obtained were significantly different / significant. While the analysis of SPSS test T on heavy metal absorption capability comparison Plumbum (Pb) concentration of 0 ppm and 0.9 ppm by Nannochloropsis sp. and Chlorella sp. showed that the results were not significantly different / non significant. On average results obtained, Nannochloropsis sp. have a higher capacity than Chlorella sp. in the bioremediation process of heavy metals Plumbum (Pb).
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Lipinska, Wiktoria, Manjunath Shinnur, Katarzyna Grochowska, Ryan Crisp und Katarzyna Siuzdak. „Formation of the Heterojunction Based on Titania Modified with Ni and Ag Sulfide Via SILAR Method - Electrochemical and Photoelectrochemical Activity“. ECS Meeting Abstracts MA2023-02, Nr. 58 (22.12.2023): 2835. http://dx.doi.org/10.1149/ma2023-02582835mtgabs.
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The great interest of TiO2 nanotubes (TiNT) is justified by large surface area, high degree of ordering, facilitated charge transport along the nanotube, mechanical strength, strong UV absorption and light scattering due to the pore specific arrangement well as wide range of potential applications in solar cells, photocatalysis and sensors [1]. However, due to the wide energy band gap of TiO2 (3.2 eV) its photoactivity is limited and therefore titania based heterojunction are formed with the photoabsorber being active in the visible range [2]. In line with this strategy, we present electrochemical and photoelectrochemical activity of TiNT modified by NiS and AgS. The electrode is fabricated via electrochemical anodization of Ti foil, thermal annealing providing anatase phase and finally Successive Ionic Layer Adsorption and Reaction (SILAR) was carried out using silver, nickel and sulfur ions precursor and with different number of deposition cycles. The characteristic Ag-S, Ag-O and S-O peaks appearing on Raman spectra indicating successful SILAR modification. The cyclic voltammetry curves for TiNT, NiS/TiNT, AgS/TiNT and AgS/NiS/TiNT electrode were registered in 0.5 M Na2SO4 (Fig.1a). Peaks found on the anodic branch of the AgS/NiS/TiNT electrode at 0 V and +0.3 V vs. Ag/AgCl/0.1 M KCl are assigned to oxidation of Ag0 to Ag1+ and Ag1+ to Ag2+, respectively. When the scan went towards cathodic direction, peak located at +0.1 V and -0.1 V indicates reduction of Ag2+ to Ag1+ and Ag1+ to Ag0, respectively [3]. Furthermore, the linear voltammetry measurements performed under visible light illumination in 0.5 M Na2SO4 is presented in Fig.1b. The best photoactivity was reached for the AgS/NiS/TiNT electrode when only 5 deposition cycles for each metal precursor was applied. The photocurrent registered at +0.5 V reaches ca. 40 µA/cm2 which is 20 times higher than for pure TiNT. Summing up, modification of titania nanotubes by nickel and silver sulfides significantly enhanced material photoelectrochemical response under visible light. Moreover, it has been proved that this synergetic effect originated from the titania/metal sulphide heterojunction that can be achieved using SILAR method. Research is financed by National Science Centre (Poland): Grant no. 2020/39/I/ST5/01781 [1] K. Siuzdak et al. RSC Advances, 5 (2015) 50379, DOI:10.1039/c5ra08407e [2] S. Chandrasekaran et al. Chemical Society Reviews, 48 (2019) 4178, DOI:10.1039/c8cs00664d [3] J.R.N. Santos et al. Electrocatalysis, 13 (2022) 713, DOI: 10.1007/s12678-022-00754-2 Figure 1
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Han, Man Ho, und Hyung-Suk Oh. „Electronic Structure Modulation of Sulfur-Retaining Nickel-Based Electrocatalyst to Improve the Oxygen Evolution Reaction“. ECS Meeting Abstracts MA2022-02, Nr. 44 (09.10.2022): 1683. http://dx.doi.org/10.1149/ma2022-02441683mtgabs.
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Water electrolysis is considered as a key energy source to produce hydrogen for achieving a clean and sustainable society. Improving the sluggish kinetics of the oxygen evolution reaction (OER) is focused to overcome the limit efficiency of water electrolysis. Transition metals, especially Ni, are one of the most promising materials for the alkaline OER because of good catalytic activities, stabilities and cost efficiency. Ni based materials, such as Ni oxyhydroxides, hydroxides, phosphides and sulfides, are intensively developed for use as OER catalysts. Recently, the sulfurization of transition metals is introduced as an effective method to improve the intrinsic electrocatalytic activities. The role of S has been summarized in 2 ways. S accelerates the regeneration of transition metals in alkaline media that S is dissolved and exchanged with O species. Mullins et al. reported Nickel oxide derived from Ni-S. It exhibits amorphous and large active surface morphology which is favorable OER. The other role is that remaining S modulates the electronic structures of Ni catalysts reducing the energy barrier for the OER. Wu et al. developed ultrathin Fe-doped Ni3S2 for overall water splitting. Based on density functional theory calculations, the Fe-doped Ni3S2 surface exhibits an optimized energy for water adsorption and dissociation, which enhances the intrinsic activity for the OER. However, in-situ/operando experimental studies regarding the effects of residual S are rare. Herein, we report the role of the remaining S in Ni catalysts that exhibit longer Ni-O bonding in the NiOOH phase produced in-situ. C-supported Fe- and Co-doped nickel sulfide catalysts (NiFeCo-S/C) is prepared using a simple impregnation method with heating under an H2S atmosphere. We tested the electrochemical properties of the NiFeCo-S/C in alkaline media of 1 M KOH. It achieved current density of 10 mA cm-2 with only overpotential of 267.2 mV. Also, it maintained the OER activities for 24 h at current densities of 10 and 50 mA cm-2, respectively. Moreover, the prepared catalyst was analyzed the change of electronic structure and bonding group using in-situ/operando X-ray absorption spectroscopy (XAFS) and surface-enhanced Raman spectroscopy (SERS) under OER condition. Based on these results, we could elucidate the effects of the remaining S during the OER. Figure 1
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Shiraiwa, Manabu, und Ulrich Pöschl. „Mass accommodation and gas–particle partitioning in secondary organic aerosols: dependence on diffusivity, volatility, particle-phase reactions, and penetration depth“. Atmospheric Chemistry and Physics 21, Nr. 3 (04.02.2021): 1565–80. http://dx.doi.org/10.5194/acp-21-1565-2021.
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Abstract. Mass accommodation is an essential process for gas–particle partitioning of organic compounds in secondary organic aerosols (SOA). The mass accommodation coefficient is commonly described as the probability of a gas molecule colliding with the surface to enter the particle phase. It is often applied, however, without specifying if and how deep a molecule has to penetrate beneath the surface to be regarded as being incorporated into the condensed phase (adsorption vs. absorption). While this aspect is usually not critical for liquid particles with rapid surface–bulk exchange, it can be important for viscous semi-solid or glassy solid particles to distinguish and resolve the kinetics of accommodation at the surface, transfer across the gas–particle interface, and further transport into the particle bulk. For this purpose, we introduce a novel parameter: an effective mass accommodation coefficient αeff that depends on penetration depth and is a function of surface accommodation coefficient, volatility, bulk diffusivity, and particle-phase reaction rate coefficient. Application of αeff in the traditional Fuchs–Sutugin approximation of mass-transport kinetics at the gas–particle interface yields SOA partitioning results that are consistent with a detailed kinetic multilayer model (kinetic multilayer model of gas–particle interactions in aerosols and clouds, KM-GAP; Shiraiwa et al., 2012) and two-film model solutions (Model for Simulating Aerosol Interactions and Chemistry, MOSAIC; Zaveri et al., 2014) but deviate substantially from earlier modeling approaches not considering the influence of penetration depth and related parameters. For highly viscous or semi-solid particles, we show that the effective mass accommodation coefficient remains similar to the surface accommodation coefficient in the case of low-volatility compounds, whereas it can decrease by several orders of magnitude in the case of semi-volatile compounds. Such effects can explain apparent inconsistencies between earlier studies deriving mass accommodation coefficients from experimental data or from molecular dynamics simulations. Our findings challenge the approach of traditional SOA models using the Fuchs–Sutugin approximation of mass transfer kinetics with a fixed mass accommodation coefficient, regardless of particle phase state and penetration depth. The effective mass accommodation coefficient introduced in this study provides an efficient new way of accounting for the influence of volatility, diffusivity, and particle-phase reactions on SOA partitioning in process models as well as in regional and global air quality models. While kinetic limitations may not be critical for partitioning into liquid SOA particles in the planetary boundary layer (PBL), the effects are likely important for amorphous semi-solid or glassy SOA in the free and upper troposphere (FT–UT) as well as in the PBL at low relative humidity and low temperature.
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Amigues, Simon, Nicolas Bibent, Arsène Gervex, Anastassiya Khan, Andrea Zitolo, Amir Gasmi, Raphael Chattot, Laetitia Dubau, Frederic Maillard und Frederic Jaouen. „Non-Precious Hydrogen Oxidation Catalysts for Anion Exchange Membrane Fuel Cells“. ECS Meeting Abstracts MA2023-02, Nr. 41 (22.12.2023): 2028. http://dx.doi.org/10.1149/ma2023-02412028mtgabs.
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Green hydrogen as an energy carrier has the potential to dramatically reduce our greenhouse gas emissions and meet the net-zero emissions targets set by the Paris Agreement countries by 2050. This hydrogen can be produced by electrolysis using water and renewable electricity, and be converted into electricity on demand in a fuel cell. Proton exchange membrane fuel cells (PEMFC) are already commercialized, but due to their acidic environment, these devices require precious metal catalysts, in particular platinum, which is an obstacle to their large-scale deployment. In contrast, anion exchange membrane fuel cells (AEMFCs) operate at high pH, facilitating the use of cost-effective and sustainable precious metal free catalysts. To catalyze the hydrogen oxidation reaction (HOR) in alkaline media, nickel has shown interesting performances to replace precious metal catalysts at the anode of AEMFCs [1]. In order to improve the intrinsic activity of nickel-based materials and reach the performance of precious metals catalysts, two approaches are studied in the literature: optimization of intrinsic properties by alloying Ni with other earth abundant elements, or core@shell nanostructuration of Ni by a protective carbon shell. We are focused on this second approach through the mechanochemical synthesis of a nickel-based Metal-Organic Framework (MOF) from a Ni2+ salt and BTC (1,3,5-benzenetricarboxylic acid), followed by pyrolysis under different atmospheres (Figure 1.a). As already shown in the literature [2], there is a significant effect of the pyrolysis atmospheres (NH3, H2, N2, in various ratios) on the electrochemical performance of the catalysts (Figure 1.b). In this study, we employed ex situ and operando studies approaches to investigate the influence of these different atmospheres on the nanoparticles structuration and to relate them to the electrochemical performances obtained. Our Ni-based anode materials were characterized by X-ray diffraction, electron microscopy, nitrogen adsorption, and electrochemical techniques, including AEMFC tests. Furthermore, the transformation of the MOF into an active catalyst was followed with in-situ X-ray absorption spectroscopy. [1] Zhao, J. Chen, W. Sun, H. Pan, «Non-Platinum Group Metal Electrocatalysts toward Efficient Hydrogen Oxidation Reaction», Adv. Funct. Mater., vol. 31, no 20, 2021, p. 2010633. [2] Ni et al., « An efficient nickel hydrogen oxidation catalyst for hydroxide exchange membrane fuel cells », Nat. Mater., vol. 21, no 7, 2022, p. 804. Figure 1
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Cao, Weijie, Tomoki Uchiyama, Neha Thakur, Mitsuharu Fujita, Ikkei Arima, Toshiki Watanabe, Kentaro Yamamoto et al. „Effect of Electrolyte Anions on the Activity of Iridium Oxide Catalysts for Water Electrolysis“. ECS Meeting Abstracts MA2023-02, Nr. 42 (22.12.2023): 2085. http://dx.doi.org/10.1149/ma2023-02422085mtgabs.
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Developing environmentally friendly and renewable energy sources is essential due to the environmental and energy security issues caused by traditional combustion of fossil fuel-based energy sources. Therefore, as a clean and sustainable energy carrier, hydrogen has attracted great attention in recent years. In this regard, water electrolysis utilizing renewable energy sources to produce hydrogen is considered one of the most promising technologies. It is believed elucidation of the reaction mechanism of highly active iridium oxides is promising for the further development of cost-efficient PEM water electrolysis catalysts. The properties of the MEA could be affected by many parameters such as the catalysts, operating temperature, and pressure1,2. Another important factor is the cation impurities that can be found in the circulating water, which could severely degrade the MEA performance during the operation of a PEM water electrolyze. However, there are less reports on anion impurities such as SO4 2- and PO4 3-. Therefore, in this study, the relationship between electrolyte anions and OER activity was investigated for IrOx catalysts with different crystal structure. By using operando X-ray absorption spectroscopy (XAS), we investigated the electronic state of Ir and O under operation potential. IrOx with different degree of crystallinity (SA3.5 and SA58) were provided by Tanaka Kikinzoku Kogyo K.K., Chemical & Refining Company and named after their BET surface areas. These two samples were then tested for electrochemical properties in different concentrations of phosphoric acid and perchloric acid, respectively. The electrochemical measurements were performed using a standard three-electrode cell connected to an MPG-205-NUC system (Bio-Logic). The cyclic voltammograms (CV) were scanned from 0.1 V to 1.2 V vs. RHE at 50 mV s-1. The electrochemical activities of the catalysts were subsequently investigated using linear sweep voltammetry (LSV) in the range of 1.1 to 1.7 V vs RHE at 10 mV s−1. operando XAS were collected using a home-made flow-type cell, where Pt wire and RHE worked as counter and reference electrodes, respectively. The catalyst ink was coated onto an Nafion membrane to prepare both the X-ray window and working electrode. The electrolyte was circulated at the flow rate of 100 mL min-1. The catalytic performance of IrOx was investigated at different types and content of electrolyte under H3PO4 and HClO4. Figure 1 shows the CVs of SA3.5 and SA58 under different types and content of electrolyte. In the presence of phosphate anions, SA3.5 showed a tendency to decrease Ir redox between 0.6 and 1.1 V with increasing electrolyte concentration. On the other hand, there were no obvious changes in SA58. It was found that IrOx catalysts have an great effect of specific adsorption of anions and low symmetry of monoclinic phase catalysts (SA 3.5) are more susceptible to anion poisoning. Figure 2 shows the result of examining the poisoning mechanism using soft X-ray XAS. O K-edge results present the formation of µ2-O (O-O) bond at around 528.7 eV, which was previously observed by Nong, H. N. et. al. through operando O-K edge measurements during OER process3. The peak intensity at 528.7 eV of the amorphous samples was in the same order as the OER activities. According to potential dependence change of the pre-edge peak, under the presence of phosphate anions, the hole formation to Ir-O hybrid orbitals was suppressed in SA3.5. This result indicates that the anion adsorbs to the active site, poisoning the catalyst surface and inhibiting the reaction. Acknowledgements This work is based on results obtained from a project (JPNP14021) commissioned by the New Energy and Industrial Technology Development Organization (NEDO) of Japan. References Zhang, Y.; Zhu, X.; Zhang, G.; Shi, P.; Wang, A.-L.; et al. J. Mater. Chem. A: 2021, 9, 5890-5914. Chen, Z.; Duan, X.; Wei, W.; Wang, S.; Ni, B.-J.; et al. Nano Energy: 2020, 78, 105270. Nong, H. N.; Falling, L. J.; Bergmann, A.; et al. Nature 2020, 587 (7834), 408-413. Figure 1
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Olejnik, Adrian, Michal Sobaszek, Maria Brzhezinskaya, Mateusz Ficek und Robert Bogdanowicz. „Electrochemistry and Electronic Structure of the Deuterium-Grown Boron-Doped Diamond Interfaces“. ECS Meeting Abstracts MA2023-02, Nr. 57 (22.12.2023): 2784. http://dx.doi.org/10.1149/ma2023-02572784mtgabs.
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Integration of the first principles quantum mechanical simulations with electrochemistry represents a difficult research area due to the complexity and large size of real systems and computational limitations. On the one hand it is highly desirable to be able to predict electrochemical properties of materials and systems from simulations to limit the money expenditure for experimental work and accelerate applications [1]. On the other hand, utilization of ab-initio simulations to understand the experimentally observed phenomena is also required to embed them into a solid theoretical framework. To fulfill this task, several multiscale approaches are used with the density functional theory (DFT) being fundamental tool for investigation of electronic structure. DFT results can be further extended to build forcefields used in molecular dynamics (MD) [2] for larger scale simulations and non-equillibrium Green's functions for investigations of electronics and spintronics of nanodevices [3]. Semiconductor electrochemistry is one of the most important areas to explore this experiment-theory interface because of the necessity to develop new materials for photovoltaics, photoelectrochemistry, energy storage and conversion. The purpose of the following talk is to show the power of this paradigm by elucidation of the deuterium-grown boron doped diamond (BDD-D) material [4]. A brief introduction to the material synthesis, chemical and physical properties is provided exploiting the synchrotron data of X-Ray absorption spectroscopy and X-Ray photoelectron spectroscopy. Then, a strong emphasis is put into merging the (photo)electrochemical data with the first principle results for better understanding of charge transfer phenomena in the nanoscale. Specifically, DFT calculations of projected local density of states clearly show the presence of highly occupied surface states on the (111) plane of BDD-D in contrast to its standard hydrogen-grown counterpart (BDD-H). The resulting surface states are capable of photocurrent generation in the visible light, which is strongly magnified in BDD-D. Moreover, photoelectrochemical measurements evidenced that photocurrents can be positive or negative depending on the bias - despite BDD being a p-type semiconductor. These confirm a profound role of surface states in the semiconductor electrochemistry and capability of photoinduced charge transfer in the modified materials. The proposed picture shines some new light on the commonly established paradigm of band bending as the key factor driving surface properties of the nanodiamond surfaces [5]. Figure. SEM images of a) BDD@D and b) BDD@H; c) grain size distribution among two samples; d) XRD patterns of the diamond films deposited in the D2/CH4 and H2/CH4 gas mixtures. Reflections at 2θ around 44°, 75°, and 91° correspond to the (111), (220), and (311) diamond lattice planes, respectively. Doubling of the reflections is related to the presence of Kα1 and Kα2 wavelengths in the X-ray radiation [4]. Acknowledgements: M.S., M.B., and M.F. thank Helmholtz-Zentrum Berlin (HZB) for the allocation of synchrotron radiation beamtime at HZB (Germany). M.S. gratefully acknowledges the financial support of these studies from the Gdansk University of Technology through the DEC-02/2021/IDUB/ II.1/AMERICIUM grant under the Americium – “Excellence Initiative – Research University” program. R.B. acknowledges the funding from the National Science Centre, Poland under the OPUS call in the Weave programme (Project number: 2021/43/I/ST7/03205). References: [1] Zhao, Shuangliang, et al. "Unified framework of multiscale density functional theories and its recent applications." Advances in Chemical Engineering. Vol. 47. Academic Press, 2015. 1-83. [2] Le, Jia-Bo, and Jun Cheng. "Modeling electrochemical interfaces from ab initio molecular dynamics: water adsorption on metal surfaces at potential of zero charge." Current Opinion in Electrochemistry 19 (2020): 129-136. [3] Datta, Supriyo. Electronic transport in mesoscopic systems. Cambridge university press, 1997. [4] Sobaszek, Michał, et al. "Highly Occupied Surface States at Deuterium‐Grown Boron‐Doped Diamond Interfaces for Efficient Photoelectrochemistry." Small (2023): 2208265. [5] Kono, Shozo, et al. "Carbon 1s X-ray photoelectron spectra of realistic samples of hydrogen-terminated and oxygen-terminated CVD diamond (111) and (001)." Diamond and Related Materials 93 (2019): 105-130. Figure 1
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Setka, Milena, Albert Behner, Milutin Smiljanic, Marjan Bele, Nejc Hodnik und Miroslav Šooš. „Microwave-Assisted Synthesis of Nitrogen-Doped Carbon Catalysts for Oxygen Reduction Reaction with Tunable Selectivity“. ECS Meeting Abstracts MA2023-02, Nr. 9 (22.12.2023): 1029. http://dx.doi.org/10.1149/ma2023-0291029mtgabs.
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The oxygen reduction reaction (ORR) is the core reaction in electrocatalysis systems such as fuel cells, metal-air batteries and hydrogen peroxide (H2O2) electro-generation. The ORR reaction mechanism has two possible pathways, namely, two-electron (2e−) or four-electron (4e−) processes that enable a reduction of oxygen into H2O2 or water (H2O), respectively. Both paths are useful where the former can provide on-site direct production of H2O2 and the latter is desired in fuel cells and batteries since it enables higher energy efficiency. Optimal ORR electrocatalyst should exhibit high activity, selectivity, stability, and low cost. Carbon materials modified with heteroatoms (e.g. nitrogen (N)) are considered potential alternatives for costly noble metal catalysts including Pt for ORR in fuel cells, and Au for the ORR to H2O2 (1,2). The typical synthesis procedure for the porous nitrogen-doped carbons (N–C) is based on the single or multiple pyrolysis steps of nitrogen-rich carbon precursor. The reactions required a pyrolysis step at the temperature range of 500-1200 °C and timing of one to tens of hours. Such processes showed a highly negative environmental impact due to high energy consumption. The production of 1 ton of activated carbon from lignocellulosic biomass feedstock requires 669.83 kWh (equivalent to an emission of 62.78 tons of CO2) (3). The synthesis of the N–C by microwave (MW) irradiation can reduce energy usage and ensure a more environmentally sustainable and economically viable approach. This procedure necessitates non-transparent materials to electromagnetic waves that can convert MW energy into heat and simultaneously enable the carbonization of the starting material. This work investigated the electrocatalytic activity towards ORR for N–C–MW catalysts derived from polyaniline (PANI) prepared in a one-step MW carbonization approach. PANI was selected due to two reasons: (i) N–C made by thermal pyrolysis of PANI showed improved electrocatalytic activity toward ORR where both the 4e− and the 2e− electron transfer pathways are feasible depending on the nature of active sides (4), (ii) PANI displayed good MW adsorption properties (5). The work aimed to identify the influence of the MW reaction condition on the resulting structure of the N–C–MW and the direction of the ORR. The N–C–MW samples were prepared under MW power of 450 and 800 W and time of 70, 140 and 210 s. The ORR activity of N–C–MW samples was investigated by cyclic voltammetry in the alkaline media (O2-saturated 0.1 M KOH). The experiment was performed in a three-electrode configuration composed of a rotating ring (Pt)–disk (glassy carbon) electrode (RRDE), a graphite rod as the counter electrode and a reversible hydrogen electrode (RHE) as the reference electrode. An influence of catalyst loading on disk electrode (0.05, 0.1 and 0.2 mg/cm2) was analyzed. All investigated MW reaction conditions resulted in the formation of porous disordered carbon structures with nitrogen and oxygen functionalities confirmed by X-ray photon-electron spectroscopy. The shorter time (70 s) and lower power (450 W) of MW treatment resulted in the formation of structures with a low carbonization rate and simultaneously a relatively poor catalytic activity for ORR (an onset potential of ∼0.65 V vs RHE). The samples carbonized under moderate (power of 450 W and 800 W, time of 140 s) and severe (power of 450 W, time of 210 s) reaction conditions showed higher selectivity to H2O2 or water H2O, respectively. The selectivity of 80 % to H2O2 was achieved for the N–C–MW-800W-140s sample at the potential of 0.6 V vs RHE at the catalyst loading of 0.05 mg/cm2. The results showcase the potential of MW carbonization in producing ORR electrocatalysts with diverse functionalization, leading to modified reaction selectivity that can be utilized in various electrocatalytic applications. Acknowledgments The research leading to these results was supported by the Johannes Amos Comenius Programme, European Structural and Investment Funds, project 'CHEMFELLS V‘ (No. CZ.02.01.01/00/22_010/0003004). References Yang, S. et al., Toward the decentralized electrochemical production of H2O2: A focus on the catalysis. ACS Catalysis, 2018. Bouleau, L. et al., Best practices for ORR performance evaluation of metal-free porous carbon electrocatalysts. Carbon, 2022. Wang, YX. et al., Quantifying environmental and economic impacts of highly porous activated carbon from lignocellulosic biomass for high-performance supercapacitors. Energies, 2022. Silva, R. et al., Efficient metal-free electrocatalysts for oxygen reduction: Polyaniline-derived N- and O-doped mesoporous carbons. Journal of the American Chemical Society, 2013. Oyharçabal, M. et al., Influence of the morphology of polyaniline on the microwave absorption properties of epoxy polyaniline composites. Composites Science and Technology, 2013. Figure 1
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Oliveira, Nicholas J., und Yushan Yan. „Evidence for Caffeine’s Positive Impact on HOR/HER Activity through Water Rearrangement As Opposed to Direct Influence on the Interfacial Electric Field“. ECS Meeting Abstracts MA2022-02, Nr. 56 (09.10.2022): 2157. http://dx.doi.org/10.1149/ma2022-02562157mtgabs.
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The puzzling pH dependence of HOR/HER leading to the approximately 2 orders of magnitude loss in platinum group metal (PGM) activity in base has hindered both the practical design of electrochemical devices as well as the fundamental understanding of electrode/electrolyte interfaces.1 Explanations for this effect have ranged from the presence of adsorbates specific to alkaline conditions,2 shifts in the electrode potential of zero free charge (pzfc) and subsequent strengthening of the interfacial electric field,3 the orientation of interfacial water molecules, and changes in the binding energy of reaction intermediates.4–6 Recently, several innovative in situ techniques have been used to probe these theories, ranging from Fourier Transform Infrared Spectroscopy (FTIR) to X-Ray Absorption Spectroscopy (XAS), as well as novel computational studies to isolate the contributions of surface adsorbed hydroxide and water.2–4,7 Additionally, the identification of caffeine as a “double-layer dopant” capable of improving HOR/HER activity 5-fold on Pt(111) has provided the field with a model system with which to systematically test these theories.8 Despite this, an overarching understanding of the mechanism and caffeine’s promoting role is still unclear, and a more rigorous analysis of the electrode surface is necessary. The electrochemical interface is traditionally viewed with a double layer model, with specific electrochemical adsorbates existing in the Inner Helmholtz Plane (IHP), the first layer of non-adsorbates at the Outer Helmholtz Plane (OHP), and water in abundance. One leading theory used to understand the activity loss from acid to alkaline environments is the decrease in surface potential relative to the pzfc in base resulting in stronger electric fields which restrict the approach of reactive intermediates to the IHP/OHP. Caffeine is suspected of reducing the IEF strength through decreasing the pzfc to relevant HOR/HER potentials, creating an acidic like environment. In this work, we challenge this notion by using SEIRAS with CO as a probe molecule to directly measure the interfacial field strength in 0.1 M KOH solutions with the model caffeine system showing HOR/HER enhancement, as well as different concentrations of various organic species with no promoting kinetic impact. FTIR studies using CO as a probe molecule to measure stark tuning rates have long been used to directly measure the interfacial electric field strength, dictated by the majority species in the OHP.9,10 The low ST rate of 22 cm-1V-1 found for all of these species in our experiments, regardless of their impact on HOR/HER kinetics, implies reductions in IEF are not solely responsible for the KOH-caffeine system’s increased activity. Rather, caffeine induces changes to the interfacial water structure as evidenced by differences in water’s ν(O-H) stretching modes, allowing for more facile kinetics, the main parameter responsible for the “apparent pH dependence” of PGM HOR/HER. Durst, J. et al. New insights into the electrochemical hydrogen oxidation and evolution reaction mechanism. Energy Environ. Sci. 7, 2255–2260 (2014). McCrum, I. T. & Koper, M. T. M. The role of adsorbed hydroxide in hydrogen evolution reaction kinetics on modified platinum. Nat. Energy 5, 891–899 (2020). Sarabia, F. J., Sebastián-Pascual, P., Koper, M. T. M., Climent, V. & Feliu, J. M. Effect of the Interfacial Water Structure on the Hydrogen Evolution Reaction on Pt(111) Modified with Different Nickel Hydroxide Coverages in Alkaline Media. ACS Appl. Mater. Interfaces 11, 613–623 (2019). Liu, E. et al. Interfacial water shuffling the intermediates of hydrogen oxidation and evolution reactions in aqueous media. Energy Environ. Sci. 13, 3064–3074 (2020). Yang, X., Nash, J., Oliveira, N. J., Yan, Y. & Xu, B. Understanding the pH Dependence of Underpotential Deposited Hydrogen on Platinum. Angew. Chemie - Int. Ed. 58, 17718–17723 (2019). Rebollar, L. et al. On the relationship between potential of zero charge and solvent dynamics in the reversible hydrogen electrode. J. Catal. 398, 161–170 (2021). Cheng, T., Wang, L., Merinov, B. V. & Goddard, W. A. Explanation of Dramatic pH-Dependence of Hydrogen Binding on Noble Metal Electrode: Greatly Weakened Water Adsorption at High pH. J. Am. Chem. Soc. 140, 7787–7790 (2018). Intikhab, S. et al. Caffeinated Interfaces Enhance Alkaline Hydrogen Electrocatalysis. ACS Catal. 10, 6798–6802 (2020). Lambert, D. K. Vibrational Stark effect of CO on Ni(100), and CO in the aqueous double layer: Experiment, theory, and models. J. Chem. Phys. 89, 3847–3860 (1988). Anderson, M. R., Blackwood, D. & Pons, S. The behavior of the infrared spectrum of carbon monoxide adsorbed at platinum electrodes from non-aqueous solvents. J. Electroanal. Chem. 256, 387–395 (1988). Figure 1
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Zhao, Yonggui, Devi Prasad Adiyeri Saseendran, Carlos A. Triana und Greta Ricarda Patzke. „(Invited) Understanding and Optimization of Versatile Molecular and Coordination Polymer-Based 3d Transition Metal Oxygen Evolution Reaction Catalysts“. ECS Meeting Abstracts MA2023-02, Nr. 58 (22.12.2023): 2823. http://dx.doi.org/10.1149/ma2023-02582823mtgabs.
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The demanding multi-electron transfer process renders the oxygen evolution reaction (OER) a bottleneck for achieving efficient clean hydrogen generation via water electrolysis.[1] Over the past decades, two main categories of catalysts, namely, homogeneous molecular and heterogeneous catalysts, have been implemented for the OER. However, due to the sluggish reaction kinetics and the aggressive reaction media of the OER, the structural integrity of both homogeneous molecular and heterogeneous catalysts faces the dramatic challenges. This calls for a thorough understanding and close monitoring of OER catalysts under their operando reaction conditions. Over the last years, we have been combining a variety of in situ/operando spectroscopy approaches with computational studies toward the comprehensive understanding of our designed catalysts at the atomic level. With this information in hand, we established a full identification of catalytically active species and sites for several systems, some of which are discussed here. First, inspired by nature’s {Mn4CaOx} OER complexes, we recently reported on the design of a tetramer Cu-bipyridyl complex for the OER.[2] Structural characterizations demonstrated a new defect-cubane structure of our designed complex, [Cu4(pyalk)4(OAc)4](ClO4)(HNEt3). We found that this Cu-bipyridyl complex can further undergo structural transformations into two unique complexes under different solution conditions, namely Cu-dimer and Cu-monomers, as revealed by in situ UV-vis and ERP characterizations as well as electrospray ionization mass spectrometry. Specifically, the Cu-monomers can be only formed in presence of carbonate buffer (pH 10.5). Otherwise, the structural transformation into a Cu-dimer complex [Cu2(pyalk)2(OAc)2(H2O)] is dominant under solution conditions. Furthermore, electrochemical characterizations revealed an overpotential of 960 mV to reach a current density of 0.1 mA/cm2 of our designed Cu-dimer catalysts, which is comparable with significant Cu-based OER electrocatalysts. To gain in-depth insights into their conversion processes, postcatalytic characterizations of Cu-based molecular catalysts were carried out based on X-ray photoelectron/absorption (XAS/XPS) spectroscopy appraoches. The results showed that nanosized Cu-oxide-based species were formed in situ in Cu-based molecular catalysts after the OER. Our study highlights the crucial role of the structural integrity of molecular catalysts in solutions for their efficient design. In parallel, we explored the structural transformations of heterogeneous electrocatalysts during the OER. As a typical example, we developed a cost-effective and high-performance NiFe-based coordination polymer (referred to as NiFe-CP) as OER electrocatalyst, which is being investigated as the best-known bimetallic combination for the OER.[3] A central element of our study is the monitoring of true catalytically active species. Results from spectroscopic characterizations revealed a kinetic restructuring of NiFe-CPs into NiFe (oxy)hydroxides during the OER. To further improve the OER activity, we introduced a facile NaBH4-assisted reduction strategy to prepare low-crystalline reduced NiFe-CP (denoted as R-NiFe-CP) OER electrocatalysts with rich structural deficiencies. These catalysts can maintain a very low overpotential of 225 mV at 10 mA/cm2 for over 120 h without any performance decline, outperforming many recent reported bimetallic OER electrocatalysts. As revealed by XAS characterizations and density functional theory (DFT) calculations, engineering of structural deficiencies not only tunes the local electronic structure but also optimizes the rate-determining step towards facilitated OH- adsorption. Noteworthy, the true OER active sites of R-NiFe-CPs originate from the in situ reconstructed Ni-O-Fe motifs. However, fundamental questions, as to (a) the role of engineered structural deficiencies in the generation of active species and (b) facilitating the formation of catalytically active dual oxygen-bridged moieties, need to be answered. Combination of time-resolved operando XAS monitoring and DFT calculations enables the tracking and understanding of the kinetic changes of active species and sites under the operando reaction conditions. We found that the OER of R-NiFe-CPs relies on the in situ formation of crucial high-valent NiIV-O-FeIVO moieties.[4] Furthermore, an anionic engineering strategy through heteroatom sulfur incorporation was carried out to obtain S-R-NiFe-CP showing faster OER kinetics. Importantly, engineered sulfur content promotes the generation of catalytically active S-NiIVO-FeIVO motifs prior to the OER. This offers a lower onset potential to trigger the OER of S-R-NiFe-CPs compared to sulfur-free R-NiFe-CPs. Moreover, our results also suggest a dual-site mechanism pathway of S-R-NiFe-CPs during the OER, in which the O-O bond formed atop the S-NiIVO-FeIVO moieties. Such an anionic modulation strategy for promoting the formation of catalytically active structural moieties and for optimizing the OER kinetics opens an avenue to optimize a wide range of heterogeneous catalysts for the OER. [1] Zhao, Y. et al. Chem. Rev. 2023 , doi.org/10.1021/acs.chemrev.2c00515. [2] Adiyeri Saseendran, D. P. et al. Chem. Comm. 2023, In Revision. [3] Zhao, Y. et al. Adv. Energy Mater. 2020, 10, 2002228. [4] Zhao, Y. et al. ACS Nano 2022, 16, 15318-15327.
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Novoselova, Inessa, Sergiy Kuleshov und Anatoliy Omel'chuk. „(Digital Presentation) Electrochemical Conversion of CO2 into Tungsten Carbides in Molten Salts“. ECS Meeting Abstracts MA2023-01, Nr. 26 (28.08.2023): 1744. http://dx.doi.org/10.1149/ma2023-01261744mtgabs.
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Huge amounts of anthropogenic emissions of the greenhouse gas carbon dioxide into the Earth's atmosphere are one of the key factors causing global warming. To mitigate the consequences of the severe climate changes caused by this phenomenon, over the last two decades great efforts of researchers have been directed towards the development of sustainable, environmentally friendly, carbon neutral and, if possible, not very expensive (in terms of used energy and inexpensive consumables) technologies for capture, conversion and storage (CCS) of CO2. Electrochemical conversion of CO2 using molten salts can rightfully be classified as CCS technology. In this case, carbon dioxide from various sources of its generation (fossil fuel power plants, industrial enterprises with a high carbon footprint) can be captured by molten salt (as a result of its physical dissolution, or chemical absorption by molten salt), and then electrochemically be converted into high value-added carbon-containing compounds: (a) carbon monoxide [1]; (b) carbon allotropes of various structures and modifications [2]; (c) refractory metal carbides [3], and various composites based on them. The reaction path and composition of the cathode products will depend on the electrolysis conditions. Elemental carbon synthesis precursor can be – carbon dioxide, directly dissolved in the molten salt mixture (direct reduction of CO2), as well as the carbonate anion, formed as a result of carbon dioxide interaction with oxide ions which are presented in the electrolyte bath (indirect reduction of CO2). This work presents the result of research concerning the electrochemical synthesis of the powders of tungsten carbides (WC and W2C) in chloride melt NaCl-KCl (1:1) under carbon dioxide pressure at the temperature range 700 – 800 оС. Refractory metal precursors are its oxy-anions (WО3; W2O7 2-; Меn x[WO4]nx-2; WO3F3 3- where Me – Na; K; Li; Mg; Ca; n – valance of metal Me). The formation of the new forms of tungsten electrochemical active particles in electrolyte is realized by the changing (control) of acidity of the melt. Carbon source is CO2, which was introduced into the electrolyzer under the excessive pressure of 0.1 – 1.7 MPa. The creation of excessive gas pressure is necessary condition for the increasing of the rate of electrolytic process (current densities) throw the rise of CO2 solubility in chloride melt. The general scheme of the high-temperature synthesis of tungsten carbides by the method of Molten Salt Carbon Electrochemical Transformation (MS-CCT) is presented in Fig. 1. The electrochemical investigations of partial and joint electroreduction of tungsten carbide precursors were carried out by the method of cyclic voltammetry. The areas of potentials and current densities, where the joint electrochemical discharge of tungsten carbide precursors (a narrow range of deposition potentials) occurs up to refractory metal and carbon takes place were found. Electrolytical synthesis of nano-sized (10 – 30 nm) powders of tungsten carbides (WC, W2C) and composites WC-C (up to 5 wt % of free carbon); W2C-WC; WC-C-Pt was carried out from the melts of different chemical composition; and the characterization of obtained products was fulfilled by the methods of chemical analysis, X-ray diffraction, DTG, BET adsorption, scanning and transmission electron microscopy. Synthesized composite materials based on tungsten carbides of various compositions were investigated as a cathode material in the reaction of electrolytic splitting of water for hydrogen production in a sulfuric acid solution [4]. The obtained results showed that the best activity has a composite of tungsten monocarbide WC with a content of free carbon up to 5 wt.%. The hydrogen onset potential for this electrode is -0.02 V, the overvoltage of hydrogen release at ik = 10 mA/cm2 is -110 mV, the exchange current is 7.0×10-4 A/cm2, the Tafel slope – -85 mV/dec. The presence of free carbon on the surface of tungsten carbides electrode improves its catalytic activity, increasing the area of the active surface. The catalytic activity of electrodes made of tungsten monocarbide increases with the introduction of platinum (up to 10 wt %) into the composite. References Kaplan V, Wachtel E, Gartsman K et al (2010) Conversion of CO2 to CO by electrolysis of molten lithium carbonate. J Electrochem Soc 157:B552–B556. Novoselova I.A., Kushkhov Kh.B., Malyshev V.V., Shapoval V.I. (2001) Theoretical foundations and implementation of high-temperature electrochemical synthesis of tungsten carbides in ionic melts. Theor. Found. Chem. Eng. 35:175–187. Novoselova I.A., Kuleshov S.V., Volkov S.V. et al (2016) Electrochemical synthesis, morphological and structural characteristics of carbon nanomaterials produced in molten salts. Electrochim Acta 211:343–355. Novoselova I, Kuleshov S, Fedoryshena E et al (2018) Electrochemical synthesis of tungsten carbide in molten salts, its properties and applications. ECS Trans 86:81–94. Figure 1
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Chida, Yoshihiro, Takeru Tomimori, Tomoaki Ebata, Noboru Taguchi, Tsutomu Ioroi, Naoto Todoroki und Toshimasa Wadayama. „Oxygen Reduction Reaction of Pt and Non-PGM Transition Metal High Entropy Alloys Single Crystal Stacking Structures“. ECS Meeting Abstracts MA2022-02, Nr. 42 (09.10.2022): 1552. http://dx.doi.org/10.1149/ma2022-02421552mtgabs.
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Introduction Nanoparticles of Pt as well as Pt-based alloys are widely used as cathode catalyst materials for proton exchange membrane fuel cells (PEMFC). However, electrochemical stability of the materials is rather low under practical operating conditions of PEMFC cathode, resulting in severe deactivation of oxygen reduction reaction (ORR). Therefore, further material’s developments are required for next-generation PEMFC cathode catalysts, i.e., more enhanced ORR durability with low platinum group metal (PGM) usage. High entropy alloys (HEAs), defined as single phase solid solutions of five or more elements in equal composition ratios, are known as thermodynamically stable, in comparison to conventional binary alloys. Furthermore, complex atomic-level local structures bring about unique electronic as well as (electro-)chemical properties that originating from lattice strains induced by specific local structures and/or so-called sluggish diffusion of the constituent elements. [1] However, to our best knowledge, no study has been made for ORR properties of Pt alloying with non-PGM Cantor alloy (fcc structure HEA with equi-atomic ratio of Cr-Mn-Fe-Co-Ni [2]) elements in strong acid condition. In this study, we synthesized lattice stacking structures of Pt/HEA(hkl) (hkl = (111), (110), (100)) through arc-plasma deposition (APD) of the Cantor alloy layer on Pt(hkl) substrate surfaces, followed by deposition of the surface Pt layer in ~10-7 Pa. Then, we performed cross-sectional STEM-EDS observations for Pt/HEA/Pt(hkl) stacking structures with atomic-level resolution and evaluated the ORR properties (initial activity and structural stability). Experimental An APD target of Cr-Mn-Fe-Co-Ni (Cantor alloy) was fabricated by sintering of equal quantity corresponding elements. 10 ML(monolayer)-thick (1 ML = ca. 0.3 nm) Cantor alloy layer (as HEA) was vacuum-deposited by APD on surface cleaned Pt(hkl) substrate surfaces at 300 K, and subsequently annealed in vacuum at 773 K for 30 minutes. Then, 4ML-thick Pt layer was deposited on the pre-deposited Cantor alloy layer at 300 K and annealed at 623 K. The samples thus prepared are designated as Pt/HEA/Pt(hkl). The atomic-level micro-structures and chemical bonding states of Pt/HEA/Pt(hkl) surfaces were characterized by cross-sectional STEM-EDS, RHEED, XPS etc. CV and LSV with the RDE method were conducted in N2-purged and O2-saturated 0.1 M HClO4. ORR activity was evaluated from j k values at 0.9 V vs. RHE by using Koutecky-Levich equation and structural stability (ORR durability) was discussed based upon activity transitions during applying the potential cycles (PCs) of 0.6(3s)‐1.0(3s) V vs. RHE in O2 saturated 0.1 M HClO4 at room temperature. Results and Discussion Atomically-resolved, cross-sectional HAADF-STEM images for Pt/HEA/Pt(hkl) (a) and EDS line profiles of elemental distributions at corresponding yellow arrows (b) are presented in Figure 1. As clearly shown in (a), irrespective of the Pt surface indices, (hkl), HEA (Cantor alloy) and surface Pt layers are epitaxially grown on the substrates. By contrast, elemental distributions in each surface normal (b) seriously depend on the substrate Pt lattice indices. Notably, severe thermal diffusion of the constituent elements including Pt is confirmed by (a) and (b) for both Pt/HEA/Pt(110) and (100). Figure 2 summarizes electrochemical results. 4ML-thick-Pt/10ML-thick-Co/Pt(hkl) that prepared under the same preparation condition of Pt/HEA/Pt(hkl), and clean Pt(hkl) (light blue and gray, respectively) are also shown as references. As shown in the figure, the Pt/HEA and Pt/Co fabricated on Pt(111) substrate (top) show quite similar CV characteristics (shrink in hydrogen adsorption charges (0 – 0.3 V) and higher potential shifts in oxygen-related species adsorption (0.6 – 1.0 V)), in comparison to clean Pt(111), and almost the same initial ORR activity. Meanwhile, the Pt/HEA fabricated on Pt(110) and (100) substrates show more reduced hydrogen absorption charges, compared with corresponding Pt/Co samples. Particularly, distinctive redox features for clean Pt(110) at 0.12 V and for Pt(100) at 0.35 V are absent for corresponding CVs, suggesting specific topmost surface atomic-structures might be formed in the electrolyte, that probably resulting from significant electronic interactions between surface Pt and HEA constituent elements (Cr, Mn, Fe, Co, Ni) and/or local strain of the surface Pt layer induced by distorted Pt-HEA lattices located nearby. One might notice that Pt/HEA/Pt(110) reveals remarkable ORR activity enhancement compared with corresponding Pt/Co/Pt(110), while the activities for Pt/HEA and corresponding Pt/Co surfaces fabricated on Pt(100) are almost the same value. At the meeting, correlations between surface atomic-level micro-structures of Pt/HEA/Pt(hkl) and ORR properties will be discussed in detail. Acknowledgement This study was supported by new energy and industrial technology development organization (NEDO) of Japan and JST SPRING, Grant Number JPMJJSP2114. Reference [1] J. Yeh, JOM, 65, 1759 (2013). [2] B. Cantor et al., Mater. Sci. Eng. A, 375, 213 (2004). Figure 1
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AIB, Ekejiuba. „Universal “Plug and Play” Real-Time Entire Automotive Exhaust Effluents, Industry Vents and Flue Gas Emissions Liquefiers: The Game Changer Approach-Phase Two Category“. Petroleum & Petrochemical Engineering Journal 7, Nr. 2 (04.04.2023): 1–56. http://dx.doi.org/10.23880/ppej-16000349.
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The first in the series of Azuberths Game Changer publications “Synergy of the Conventional Crude Oil and the FT-GTL Processes for Sustainable Synfuels Production: The Game Changer Approach-Phase One Category” a.k.a. (DOI: 10.23880/ppej16000330) is targeted at reducing 80 per cent CO2 emissions from the internal combustion engines by upgrading from the conventional crude oil refinery products to the synthetic fuels products (ultra-low-carbon fuels). This paper will focus on the complete elimination of the remaining 20 per cent CO2 emissions (i.e. to achieve zero- CO2 emissions) in transportation and power generating internal combustion engines as well as in the other centralized emissions/emitters such as petroleum industry flare lines, industrial process and big technology industries scrubber flue gas, et cetera. This invention stems from similar biblical quote {Isaiah 6:8-New International Version (NIV)} which states, and then I heard the voice of the Lord saying, “Whom shall I send? And who will go for us?” And I (Isaiah) said, “Here am I. Send me!” Laterally, in this case I (Azunna) said, “Here am I. Please use me”. Hence the aftermath, IJN-Universal Emissions Liquefiers is a plug and play units for all categories of pollutants discharge into the atmosphere. The work is motivated by the scientific facts that (i) The release of CO2 from automotive exhaust effluents, industry vents and flue gas emissions into the atmosphere contributes to greenhouse gas (GHG) accumulation causing global warming hence climate changes issues such as flooding of coastlines/sea-rising, melting of the glaciers, disrupted weather patterns, bushburning/wildfire, depletion of Ozone layer, smog and air pollution, acidification of water bodies, runaway greenhouse effect, etc. (ii) Every gas stream (e.g., flue gas) can be made liquid by e.g. a series of compression, cooling and expansion steps and once in liquid form, the components of the gas can be separated in a distillation column. (iii) Captured liquefied gases can be put to various uses, especially carbon dioxide (CO2 ), which can be used for the production of renewable energy via Synfuels such as the e-fuel/solar fuel. The natural atmosphere is composed of 78% nitrogen, 21% oxygen, 0.9% argon, and only about 0.1% natural greenhouse gases, which include carbon dioxide, organic chemicals called chlorofluorocarbons (CFCs), methane, nitrous oxide, ozone, and many others. Although a small amount, these greenhouse gases make a big difference - they are the gases that allow the greenhouse effect to exist by trapping in some heat that would otherwise escape to space. Carbon dioxide, although not the most potent of the greenhouse gases, is the most important because of the huge volumes emitted into the air by combustion of fossil fuels (e.g., gasoline, diesel, fuel oil, coal, natural gas). In general, the major contributors to the greenhouse effect are: Burning of fossil fuels in automobiles, deforestation, farming processing and manufacturing factories, industrial waste and landfills, increasing animal and human respiration, etc. The increased number of factories, automobiles, and population increases the amount of these gases in the atmosphere. The greenhouse gases never let the radiations to escape from the earth atmosphere and increase the surface temperature of the earth. This then leads to global warming. The petroleum industry well sites vent/flare gases (methane, ethane, propane, butanes, H2 O (g), O2 , N2 , etc.). Internal combustion engines (automobiles-cars, vehicles, ships, trains, planes, etc.) release exhaust effluents (containing H2 O (g), CO2 , O2 , and N2 ); steam generators in large power plants and the process furnaces in large refineries, petrochemical and chemical plants, and incinerators burn considerable amounts of fossil fuels and therefore emit large amounts of flue gas to the ambient atmosphere. In general, Flue gas is the gas exiting to the atmosphere via a “flue”, which is a pipe or channel for conveying exhaust gases from a fireplace, oven, furnace, boiler or steam generator. The emitted flue gas contains carbon dioxide CO2 , carbon monoxide CO, sulphur oxide SO2 , nitrous oxide NO and particulates. Furthermore, GTL plants produce CO2 , H2 O and waste heat, while both pyrolysis and gasification plant generate gaseous products consisting of (a mixture of non-condensable gases such as H2 , CO2 , and CO and light hydrocarbons “e.g. CH4 ” at room temperature, as well as H2 O (g), O2 and complex hydrocarbons e.g. C2 H2 , C2 H4 , etc.). In general, all combustion is as a result of air-fuel mixture burning (i.e. air or oxygen mixing directly with biomass/ coal or with liquid/gaseous hydrocarbon inside internal combustion engines), releases carbon dioxide and steam (H2 O) back into the atmosphere as well as producing energy for work. Specifically, during combustion, carbon combines with oxygen to produce carbon dioxide (CO2 ). The principal emission from transportation and power generating internal combustion engines is carbon dioxide (CO2 ). The level of CO2 emission is linked to the amount of fuel consumed and the type of fuel used as well as the individual engine’s operating characteristics. For instance, diesel-powered engines have higher emission than petrol/gasoline-powered engines. Although emphasis is places more on CO2 , this investigation is ultimately concerned with the real-time liquefaction of all the components of gaseous release/emissions -related to air pollution/health problem. It is believed that the mortality rate from air pollution is eight times larger than the mortality caused by car accidents each year. Pollutants with the strongest evidence for public health concern include particulate matter (PM), ozone (O3 ), nitrogen dioxide (NO2 ) and sulphur dioxide (SO2 ). All the exhaust effluents gases/flue gas and vent/flare gases are captured by liquefying them and then put to various uses, to achieve “Net zero” emissions. Fundamentally, the objective of the present invention is to develop a compact device (Universal Emissions Liquefiers) that can be retro-fitted onto the exhaust tailpipe-end of the internal combustion engines (diesel-powered, gasoline-powered, and hybrid automobiles-cars, vehicles, SUV’s, trucks, motor cycles, tri-cycles, portable electric generators, sea and cargo ships/ boats, trains, planes, rockets, etc.) and outlet of industrial machines that release flue gases through exhaust/scrubber channels, as well as crude oil, refined products storage tanks that vent greenhouse gases into the atmosphere, coal processing units/ plants and turn them into liquid { CO2 (l), N2 (l), O2 (l), etc.} or powdered components or chemically transform them in realtime with selective catalysts to any other specific compound, e.g. treating CO2 with hydrogen gas (H2) can produce methanol (CH3 OH), methane (CH4 ), or formic acid (HCOOH), while reaction of CO2 with alkali (e.g. NaOH) can give carbonates (NaHCO3 ) and bicarbonates (Na2 CO3 ). Nitrogen (N2 ) to ammonia (NH3 ) or Hydrazine (N2 H4 ), and molecular oxygen (O2 ) to hydrogen peroxide (H2 O2 ), et cetera. Alternatively, in new automobiles designs, the universal emissions liquefiers’ device can be directly net-worked on the floor alongside the catalytic converters and may eliminate the need for muffler/silencer/resonator. This is achieved by the application of any of the five main gas capture/separation technologies: Liquid absorption, Solid adsorption, Membrane separation (with and without solvent- organic or inorganic), Cryogenic refrigeration/distillation, and Electrochemical pH-swing separation or their combination to selectively trap and liquefy the individual pollutants. According to the fact from CarBuster, almost 0.009 metric tons of carbon dioxide is produced from every gallon of gasoline burned, which means that the average car user makes about 11.7 tons of carbon dioxide each year from their cars alone
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Ituen, Ekemini, Ambrish Singh, Lin Yuanhua und Onyewuchi Akaranta. „Green synthesis and anticorrosion effect of Allium cepa peels extract-silver nanoparticles composite in simulated oilfield pickling solution“. SN Applied Sciences 3, Nr. 6 (31.05.2021). http://dx.doi.org/10.1007/s42452-021-04670-w.
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AbstractAn alternative green approach through which nanoscience/nanotechnology could be applied in the industry is being demonstrated in this study. Ethanol extracts of Allium cepa peels (Et-ACPE) is used to mediate the synthesis of silver nanoparticles (Et-AgNPs) at room temperature. Stable crystalline, monodisperse and non-agglomerated spherical NPs with zeta potential of −46.2 ± 0.1 mV and plasmon absorption at 435 nm are obtained. Silver atoms are predominantly oriented towards the Ag (111) plane in a face centered cubic structure with a = b = c = 4.0968 Å having $$\alpha = \beta = \gamma = 90^\circ$$ α = β = γ = 90 ∘ . The surfaces of the NPs becomes rich in electron cloud due to O atoms supplied by capped phyto-compounds of Et-ACPE. This enhances adsorption potential and more efficient inhibition (up to 90% at 30 °C) of X80 steel corrosion in 1 M HCl solution than using the crude extract. Investigation of corrosion products and morphologies of the steel surface by FTIR, SEM/EDS and AFM techniques reveals efficient surface protection through adsorption of Et-AgNPs facilitated mainly by O and –C = C– sites. Findings prove that the Et-AgNPs is a more efficient and thermally stable alternative ecofriendly anticorrosion additive for industrial cleaning and pickling operations than the crude extract.
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Shamohammadi, Shayan, und Bahar Shamohammadi. „Mass-time equivalence in dynamic equilibrium systems“. Applied Water Science 14, Nr. 3 (10.02.2024). http://dx.doi.org/10.1007/s13201-023-02093-z.
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AbstractThe truth of time has been debated for more than two centuries. Scientists like Leibniz, Einstein, Rowley, Wheeler and DeWitt believe that it is the result of change in the world and is not original. According to our research, only Einstein introduced the law of space–time and showed that time is woven in space (general relativity), but no one (at least in classical physics) explained the relationship between time and changes in the world (mass and energy). has not provided In the rest of the references, only mathematical and theoretical topics are presented. In kinetic experiments (in various scientific fields), time is used as a variable to plot kinetic curves. This choice is neither scientific nor based on principled modeling. For this reason, kinetic models are presented experimentally. The aim of this research is (1) to introduce the "dynamic mass (∂Mout/∂Min)" equation as a platform for mass-based modeling in open systems. (2) Introducing the relationship between mass (m) and time (t) or mass-time equivalence in mass flows (mass conversion or mass transfer system). (3) Expansion of time relativity in mass-mass systems. To achieve the objectives of the study, the equation "dynamic mass (∂M/∂M)" based on the law of conservation of mass has been introduced for the first time. Then, using the dynamic mass equation, the absorption model was presented in two mass forms (mass-mass curve) and time (mass-time curve). Then, using Fe2+, Pb2+, Cr6+, Ni2+, Cd2+and As2+ elements and Jacobi activated carbon, Iranian activated carbon, and blowy sand adsorbents, routine kinetic and isotherm tests were performed separately. To evaluate the absorption model, three methods were used: (1) evaluation by evaluation indices (R2 and RMSE) and (2) comparison of the "temporal form of the model" with the kinetic models of absorption (Lagergren and Ho et al.) and (3) comparison of the "mass form of the model" with Shammahmadi adsorption isotherm model.
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Domínguez-Patiño, M. L., M. Chávez-Castillo, A. Rodríguez-Martínez, R. M. Melgoza Alemán, E. Jiménez-Ferrer und M. Herrera-Ruíz. „Application of clay as a means of support to biomaterial with anti-inflammatory agents“. MRS Proceedings 1277 (2010). http://dx.doi.org/10.1557/proc-1277-s6-15.
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In the last fifteen years, there have been significant changes in the production of medicines, mainly in the addition of new components to the formulation of solid dosage forms. The current trend of “back to nature” to lead to a healthier life has led those who are engaged in the pharmaceutical field to develop new formulations that allow the use of natural products of plant originFor example, excipient ingredients, used as carriers for a drug's active ingredients, are now being used. These are incorporated into a drug in order to facilitate the drug's preparation, maintenance, or administration. The excipient is beneficial to the patient because it allows the drug to be easily administered and absorbed by the human body [3]There is evidence that the clays have great potential for both absorption and adsorption due to its tiny particles. In addition, it has been reported that some clays have an effective antiseptic and healing ability [5–8]In the present work, a clay called bentonite was tested as a support vehicle of an inflammatory agent derived from a Mexican native plant called Distictis buccinatoria, commonly named “Tonacaxóchitl”. Studies carried out by Rojas et al. have shown that the organic extract of this plant has important antibacterial, antifungal, cytotoxic and anti-inflammatory properties [9]
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Ye, Lu-ting, Zong-hua Dong, Jun Liu, Feng Guan und Jian Ge. „Modulation Mechanism of Proanthocyanidins from Leaves of Bayberry (Myrica rubra Sieb. Et Zucc.) on Hyperlipemic Rats Induced by High-fat-diet“. Journal of Pharmaceutical Research International, 27.04.2022, 8–22. http://dx.doi.org/10.9734/jpri/2022/v34i35a36159.
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Aim: To investigate the lipid-lowering effect of proanthocyanidins from Bayberry leaf (BLP) in rat model of hyperlipidemia and to clarify the underlying molecular mechanism.
Study Design: The study includes in-vitro and in-vivo experiments in rat model.
Place and Duration of Study: College of Life Sciences, China Jiliang University, Zhejiang Province, China, between March 2021 to December 2021.
Methodology: BLP were preliminarily characterized. The adsorption rate of BLP was determined based on in-vitro binding to bile acids. The effect of BLP on membrane transport of bile acids was examined through Caco-2 mono-layer in trans-well. The effect of BLP on serum enzyme activity and lipid metabolism genes expression were also investigated in a high-fat diet rat model.
Results: Total poly-phenol and proanthocyanidins contents were 97.93% and 82.25% respectively, using gallic acid and Epigallocatechin-3-O-Gallate (EGCG) as equivalent. The total flavonoid content was 12.05% (quercetin as equivalent) and the average polymerization degree of BLP was determined as 4.51. And the in-vitro average binding rates of BLP to bile acids were all higher than 80%. Meanwhile, the membrane transport of bile acids in Caco-2 monolayer cells were significantly obstructed by BLP. Furthermore, the total cholesterol (TC), triglyceride (TG) and low density lipoprotein cholesterol (LDL-C) concentrations in rat serum were markedly decreased after 28-day of BLP treatment. And the hepatic steatosis was significantly ameliorated in high-dose BLP treatment group compared with high fat group. High-dose administration of BLP significantly reduced the levels of 3-hydroxy-3-3methylglutary-CoA (HMG-CoA) reductase, while the levels of ATP binding cassette transporters (ABCG-5), liver X receptor-α (LXR-α) and cholesterol-7α-hydroxylase (CYP7A1) were significantly increased.
Conclusion: BLP can mediate the serum lipid metabolism via preventing bile acids re-absorption, reducing oxidative stress and regulating the expression of lipid metabolism-related genes.