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Khajehpour, Maryam, S. Reza Etminan, Jon Goldman, Fred Wassmuth i Steven Bryant. "Nanoparticles as Foam Stabilizer for Steam-Foam Process". SPE Journal 23, nr 06 (10.09.2018): 2232–42. http://dx.doi.org/10.2118/179826-pa.
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Summary Steam foams have been considered effective additives for unconventional oil-recovery processes. Conventionally, for steam-foam applications, chemical additives are injected with steam. However, this procedure can have serious challenges because of poor thermal stability of additives and high volume of additives loss caused by adsorption to the rock surface. To overcome these limitations, nanoparticles can be used as novel additives to improve generation and stabilization of the foams for steam-foam applications. In this study, silica nanoparticles in synergy with surfactants have been used as steam additives. Dynamic light scattering (DLS), a foam-height test using N2 at reservoir conditions, and thermal-stability analysis were designed to measure nanoparticle size distribution in brine, foamability, and thermal stability of the additive solutions, respectively. Subsequently, coreflooding tests were performed to evaluate the synergistic effect of nanoparticles and surfactants on the foam performance and oil recovery. We observed an optimal ratio of nanoparticle and surfactant that yields the best foam-generation performance in bulk medium. Herein, surface-treated silica nanoparticles have been tested with two of our candidate surfactants. The nanoparticles alone generate a small amount of foam, whereas each surfactant generates a small-to-moderate amount of foam. Synergy is demonstrated by the system that contains 0.1-wt% nanoparticles (the optimal concentration) and 0.5-wt% surfactant solution at neutral pH (≈7), as it leads to approximately 67 and 50% greater foam height, respectively, for Surfactants A and B than foam height observed in tests with surfactants only, in bulk medium. Corefloods with coinjected steam and water containing nanoparticles and surfactant confirm the synergy, exhibiting measurable improvement in mobility-reduction factor (MRF) and steam control, compared with coinjection of steam and water containing only surfactant.
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Jasinski, Jacek, Kent E. Pinkerton, I. M. Kennedy i Valerie J. Leppert. "Spatially Resolved Energy Electron Loss Spectroscopy Studies of Iron Oxide Nanoparticles". Microscopy and Microanalysis 12, nr 5 (23.08.2006): 424–31. http://dx.doi.org/10.1017/s1431927606060491.
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The oxidation state of iron oxide nanoparticles co-generated with soot during a combustion process was studied using electron energy-loss spectroscopy (EELS). Spatially resolved EELS spectra in the scanning transmission electron microscopy mode were collected to detect changes in the oxidation state between the cores and surfaces of the particles. Quantification of the intensity ratio of the white lines of the iron L-ionization edge was used to measure the iron oxidation state. Quantitative results obtained from Pearson's method, which can be directly compared with the literature data, indicated that the L3 /L2-intensity ratio for these particles changes from 5.5 ± 0.3 in the particles' cores to 4.4 ± 0.3 at their surfaces. This change can be directly related to the reduction of the iron oxidation state at the surface of the particles. Experimental results indicate that the cores of the particles are composed of γ-Fe2O3, which seems to be reduced to FeO at their surfaces. These results were also supported by the fine structure of the oxygen K-edge and by the significant chemical shift of the iron L-edge.
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de Lima, Scarllett L. S., Fellipe S. Pereira, Roberto B. de Lima, Isabel C. de Freitas, Julio Spadotto, Brian J. Connolly, Jade Barreto i in. "MnO2-Ir Nanowires: Combining Ultrasmall Nanoparticle Sizes, O-Vacancies, and Low Noble-Metal Loading with Improved Activities towards the Oxygen Reduction Reaction". Nanomaterials 12, nr 17 (1.09.2022): 3039. http://dx.doi.org/10.3390/nano12173039.
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Although clean energy generation utilizing the Oxygen Reduction Reaction (ORR) can be considered a promising strategy, this approach remains challenging by the dependence on high loadings of noble metals, mainly Platinum (Pt). Therefore, efforts have been directed to develop new and efficient electrocatalysts that could decrease the Pt content (e.g., by nanotechnology tools or alloying) or replace them completely in these systems. The present investigation shows that high catalytic activity can be reached towards the ORR by employing 1.8 ± 0.7 nm Ir nanoparticles (NPs) deposited onto MnO2 nanowires surface under low Ir loadings (1.2 wt.%). Interestingly, we observed that the MnO2-Ir nanohybrid presented high catalytic activity for the ORR close to commercial Pt/C (20.0 wt.% of Pt), indicating that it could obtain efficient performance using a simple synthetic procedure. The MnO2-Ir electrocatalyst also showed improved stability relative to commercial Pt/C, in which only a slight activity loss was observed after 50 reaction cycles. Considering our findings, the superior performance delivered by the MnO2-Ir nanohybrid may be related to (i) the significant concentration of reduced Mn3+ species, leading to increased concentration of oxygen vacancies at its surface; (ii) the presence of strong metal-support interactions (SMSI), in which the electronic effect between MnOx and Ir may enhance the ORR process; and (iii) the unique structure comprised by Ir ultrasmall sizes at the nanowire surface that enable the exposure of high energy surface/facets, high surface-to-volume ratios, and their uniform dispersion.
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Gunel, Imanova, Bekpulatov Ilkhom, Aliyev Anar i Barkaoui Sami. "Importance of the radiations in water splitting for hydrogen generation". Annals of Advances in Chemistry 7, nr 1 (14.03.2023): 031–36. http://dx.doi.org/10.29328/journal.aac.1001040.
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The review article examines the production of molecular hydrogen from the decomposition of water by various irradiation methods. The article shows different types of radiation: UV radiation, visible radiation, gamma radiation, X-ray radiation and neutron radiation. Electrons generated by radiation inside a nanoparticle of radius R suspense in fluid water are diffused with equal probability in all directions inside the particle and gradually lose their kinetic energy as a result of elastic and inelastic collisions. Some of these electrons are transported to the nanoparticle surface during the physical and physicochemical stages of the process and emitted into the water. It is extremely important for the formation of nanostructured materials after exposure to ordered nanostructure from the new phase with a period of a few nanometers, promoting the preservation of the properties of materials under high irradiation.
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Yang, Shaobo, Shung-Hsiang Wu, Yu-Sheng Lin, Chun-Jui Chu i C. C. Yang. "Surface plasmon coupling effects on the behaviors of radiative and non-radiative recombination in an InGaN/GaN quantum well". Journal of Applied Physics 133, nr 2 (14.01.2023): 023104. http://dx.doi.org/10.1063/5.0132941.
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Although surface plasmon (SP) coupling has been widely used for enhancing the emission efficiency of an InGaN/GaN quantum well (QW) structure, the interplay of the carrier transport behavior in the QW with SP coupling, which is a crucial mechanism controlling the SP-coupling induced QW emission enhancement, is still an issue not well explored yet. To understand the effects of SP coupling on the radiative and non-radiative recombination behaviors of carriers in a QW structure, the temperature-dependent time-resolved photoluminescence spectroscopies of two QW samples of different indium contents with surface Ag nanoparticles are studied. A two-single-exponential model is used for calibrating their radiative and non-radiative decay times. The SP coupling process, which transfers carrier energy from a QW into the SP resonance mode for effective radiation and increases the effective radiative recombination rate, produces energy-dependent carrier depletion and, hence, disturbs the quasi-equilibrium condition of carrier distribution. In this situation, a strong carrier transport process occurs targeting a new quasi-equilibrium condition that enhances non-radiative recombination and, hence, reduces the benefit of using the SP coupling technique. To alleviate this problem of SP-coupling induced energy loss, a weak energy-dependent or broad-spectrum SP coupling process is recommended.
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Fujii, Minoru, i Hiroshi Sugimoto. "(Invited, Digital Presentation) Enhancement of Magnetic Dipole Transition of Molecules By Silicon Nanoparticle Nanoantenna". ECS Meeting Abstracts MA2022-01, nr 20 (7.07.2022): 1081. http://dx.doi.org/10.1149/ma2022-01201081mtgabs.
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A nanoantenna is a nanodevice that manipulates light propagation and enhances light-matter interaction at the nanoscale. Integration of an emitter into a nanoantenna capable of increasing local density of photonic states at the emission wavelength results in the enhanced spontaneous emission rate (Purcell effect). The most widely studied nanoantennas for the Purcell enhancement are plasmonic nanoantennas made from gold or silver nanostructures supporting surface plasmon resonances. In most cases, nanoantennas have been used for the enhancement of electric dipole-allowed transition of a molecule. In addition, recently, nanoantennas capable of enhancing magnetic dipole transition of a molecule are attracting attention. For the magnetic Purcell enhancement, nanoantennas have to have magnetic resonances at the optical frequency. Although it is possible to achieve magnetic resonances at the optical frequency by plasmonic nanostructures, the inherent absorption loss of noble metals limits the magnetic Purcell enhancement. On the other hand, nanoparticles of high refractive index dielectrics inherently have low-loss magnetic-type Mie resonances at the optical frequency, and thus are potentially more attractive as a material to realize large magnetic Purcell enhancement. We have developed spherical nanoparticles of crystalline silicon (Si) having the magnetic dipole (MD) and quadrupole (MQ) Mie resonances at the optical frequency [1]. In this work, to demonstrate the potential of a Si nanoparticle as a nanoantenna for the magnetic Purcell enhancement, we develop a composite nanoparticle, that is, a Si nanosphere decorated with europium ion (Eu3+) complexes, in which magnetic dipole emission of Eu3+ is efficiently coupled to the magnetic Mie modes of the nanosphere [2]. We systematically investigate the light scattering and photoluminescence spectra of the coupled system by means of single particle spectroscopy. The results are shown in Figure 1. By tuning the MQ Mie resonance of a Si nanosphere to the 5D0-7F1 magnetic dipole transition of Eu3+, the branching ratio between the magnetic and electric dipole (5D0-7F2) transitions is enhanced up to 7 times. The observed large magnetic Purcell enhancement offers an opportunity to develop novel fluorophores with enhanced magnetic dipole emission. Furthermore, the enhanced magnetic field of dielectric Mie resonators enhances otherwise very weak absorption due to magnetic dipole transition, and makes direct excitation of triplet states of a molecule possible [3]. Direct excitation of triplet states reduces photon energy necessary for energy conversion and chemical reactions utilizing a triplet state compared to a conventional process involving singlet-singlet excitation and singlet-triplet intersystem crossing. [1] H. Sugimoto, et. al., "Mie Resonator Color Inks of Monodispersed and Perfectly Spherical Crystalline Silicon Nanoparticles" Advanced Optical Materials, 8 (2020) 2000033. [2] H. Sugimoto, and Minoru Fujii, "Magnetic Purcell Enhancement by Magnetic Quadrupole Resonance of Dielectric Nanosphere Antenna", ACS Photonics, 8 (2021) 1794. [3] H. Sugimoto, et. al., "Direct Excitation of Triplet State of Molecule by Enhanced Magnetic Field of Dielectric Metasurfaces", Small, 2021, DOI: 10.1002/smll.202104458. Figure 1: Photoluminescence (red curves) and scattering (black curves) spectra of single Si naosphere-Eu3+ complex composite nanoparticles with different Si nanosphere diameters. The diameters are shown at the right end of the figure. Figure 1
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Srivastava, Soamyaa, i Jayanand Manjhi. "Facile Characterization of Titanium Dioxide Nano- particles Prepared via Hydrothermal Method with in-situ Surface Modification". International Journal of Pharmaceutical Sciences and Nanotechnology(IJPSN) 15, nr 4 (15.09.2022): 6034–42. http://dx.doi.org/10.37285/ijpsn.2022.15.4.3.
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Aim: The present study is focused on the synthesis and characterization of titanium dioxide nanoparticles prepared via the hydrothermal method prepared via in-situ surface modification.
Purpose of the study: The proposed research is based on the requirement of alternate antimicrobial therapies. The global misuse and overuse of antibiotics have given rise to the antibiotic resistance crisis. The emergence of multi-drug resistant bacteria has failed the conventional treatment methods involving antibiotics. To meet the need for efficient alternate strategies, metal oxide nanoparticles such as titanium dioxide are explored since it's known for their preventing and treating infections.
Method: Titanium dioxide nanoparticles were successfully synthesized via hydrothermal and Surface modification of nanoparticles in dehydrated ethanol at room temperature. The obtained nanoparticles are characterized by utilizing Scanning Electron Microscope, Transmission Electron Microscope, Energy Dispersive X-ray Spectroscopy, Zeta Potential Analysis, Thermogravimetric analysis, and Fourier transform Infrared spectroscopy.
Results: According to scanning electron microscopy and transmission electron microscopy, the morphological analysis of the synthesized titanium dioxide was spherical shaped and had an average size of 5-20nm and a size distribution of 14-20nm. The Energy Dispersive X-ray spectroscopy analysis depicted the percentage of elements in TiO2 as Ti (47.10%) and O2 (52.90%). The zeta potential for titanium dioxide was reported as -13.39, and the negative value indicated superior physical stability of nanoparticles in a suspension. The Fourier Transform Infrared spectroscopy peak at 1417.68 indicated the O-Ti-O bond in anatase morphology. While Thermogravimetric analysis showed three main stages of mass loss, there was no mass loss after 503°C, which started oxide formation.
Conclusion: It was concluded from the present study that the synthesis of titanium dioxide is an economical process and yields excellent nanoparticles via the hydrothermal method. Characterization of the nanomaterial allowed us to determine the thermal stability, morphology, and purity of titanium dioxide nanoparticles.
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Li, Jingwei, Xuwen Liu, Quanmin Xie, Yongsheng Jia, Jinshan Sun i Yingkang Yao. "Cryogel-Templated Fabrication of n-Al/PVDF Superhydrophobic Energetic Films with Exceptional Underwater Ignition Performance". Molecules 27, nr 20 (14.10.2022): 6911. http://dx.doi.org/10.3390/molecules27206911.
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The rapid heat loss and corrosion of nano-aluminum limits the energy performance of metastable intermolecular composites (MICs) in aquatic conditions. In this work, superhydrophobic n-Al/PVDF films were fabricated by the cryogel-templated method. The underwater ignition performance of the energetic films was investigated. The preparation process of energetic materials is relatively simple, and avoids excessively high temperatures, ensuring the safety of the entire experimental process. The surface of the n-Al/PVDF energetic film exhibits super-hydrophobicity. Because the aluminum nanoparticles are uniformly encased in the hydrophobic energetic binder, the film is more waterproof and anti-aging. Laser-induced underwater ignition experiments show that the superhydrophobic modification can effectively induce the ignition of energetic films underwater. The results suggest that the cryogel-templated method provides a feasible route for underwater applications of energetic materials, especially nanoenergetics-on-a-chip in underwater micro-scale energy-demanding systems.
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Гуренцов, Е. В., А. В. Еремин i С. А. Мусихин. "Исследование испарения лазерно-нагретых железо-углеродных наночастиц при помощи анализа их теплового излучения". Журнал технической физики 89, nr 8 (2019): 1200. http://dx.doi.org/10.21883/jtf.2019.08.47891.2335.
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AbstractEvaporation of iron nanoparticles in carbon shells under pulsed laser irradiation is analyzed. Iron–carbon nanoparticles are synthesized in a shock tube reactor with the aid of pyrolysis of the 0.25% Fe(CO)_5 + 0.25% C_6H_6 mixture in argon. Laser radiation is used for additional heating to temperatures that exceed the evaporation threshold of the iron core of nanoparticles. Time profiles of the thermal radiation of laser-heated nanoparticles are measured. The two-color pyrometry is used to determine the evaporation temperature of nanoparticles, and the laser extinction makes it possible to monitor the loss of volume fraction of the condensed phase upon evaporation. Approximation of experimental signals of laser-heated nanoparticles using model curves is employed to determine effective enthalpy of evaporation of iron–carbon nanoparticles. It is shown that the iron core of nanoparticles is evaporated through the carbon shell and the energy spent by such a process is approximately twice greater than the evaporation enthalpy of bulk iron with free surface.
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Tommasi, Matteo, Francesco Conte, Mohammad Imteyaz Alam, Gianguido Ramis i Ilenia Rossetti. "Highly Efficient and Effective Process Design for High-Pressure CO2 Photoreduction over Supported Catalysts". Energies 16, nr 13 (27.06.2023): 4990. http://dx.doi.org/10.3390/en16134990.
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The photocatalytic reduction of CO2 into solar fuel is considered a promising approach to solving the energy crisis and mitigating the environmental pollution caused by anthropogenic CO2 emission. Some powder photocatalysts have been demonstrated as efficient, but their drifting properties, along with difficult separation (catalyst and product), make continuous mode reaction very challenging, particularly in the liquid phase. In order to make this process commercially viable and economically more efficient, we have developed a simple and scalable method for immobilizing TiO2 P25 over the surface of glass slides using an organic-based surfactant. Improved adhesion properties and the homogeneous dispersion of catalyst nanoparticles were achieved. A holder was designed with 3D printing technology in such a way that it can hold up to six slides that can be dipped simultaneously into the suspension or solution of desired materials for a uniform and homogeneous deposition. The resulting surfaces of the dip-coated materials (e.g., TiO2 P25) were further modified by adding metallic nanoparticles and thoroughly characterized via XRD, DRS UV–Vis, SEM, and SEM–EDX. Photocatalytic tests have been performed for two major applications, viz., hydrogen production via the photoreforming of glucose and the photoreduction of CO2 into different solar fuels. The latter tests were performed in a specially designed, high-pressure reactor with Ag/P25 supported catalysts, which exhibited about three times higher formic acid productivity (ca. 20 mol/kgcat h) compared to the dispersed catalyst, with enhanced stability and recoverability. It is to note that catalysts deposited on the glass slides can easily be recovered and the materials did not show any weight loss. To the best of our knowledge, the obtained formic acid productivity is highest among the published literature.
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Dąda, Anna, Paweł Błaut, Maciej Kuniewski i Paweł Zydroń. "Analysis of Selected Dielectric Properties of Epoxy-Alumina Nanocomposites Cured at Stepwise Increasing Temperatures". Energies 16, nr 5 (21.02.2023): 2091. http://dx.doi.org/10.3390/en16052091.
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The paper presents the effects of gradual temperature curing on the dielectric properties of epoxy nanocomposite samples. Samples were prepared based on Class H epoxy resin filled with nano-alumina (Al2O3) for different wt% loadings (0.5 wt% to 5.0 wt%) and two different filler sizes (13 nm and <50 nm), i.e., two different specific surface area values. During the research, specimen sets were cured gradually at increasingly higher temperatures (from 60 °C to 180 °C). Broadband dielectric spectroscopy (BDS) was used to determine the characteristics of the dielectric constant and the dielectric loss factor in the frequency range from 10−3 Hz to 105 Hz. As a result, it was possible to analyze the impact of the progressing polymer structure thermosetting processes on the observed dielectric parameters of the samples. The nano-Al2O3 addition with 0.5 wt%, 1.0 wt%, and 3.0 wt% resulted in a decrease in dielectric constant values compared to neat epoxy resin samples. The most significant reductions were recorded for samples filled with 0.5 wt% of 13 nm and <50 nm powders, by about 15% and 11%, respectively. For all tested samples, the curing process at a gradually higher temperature caused a slight decrease in the dielectric constant (approx. 2% to 9%) in the whole frequency range. Depending on the nanofiller content and the curing stage, the dielectric loss factor of the nanocomposite may be lower or higher than that of the neat resin. For all tested samples cured at 130 °C (and post-cured at 180 °C), the differences in the dielectric loss factor characteristics for frequencies greater than 100 Hz are low. For frequencies < 100 Hz, there are prominent differences in the characteristics related to the size of the nanoparticle and the individual wt% value. At a small nanofiller amount (0.5 wt%), a decrease in the dielectric constant and dielectric loss factor was observed for frequencies < 100 Hz for samples with nanofillers of both sizes.
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Moustafa, Essam B., A. Melaibari, Ghazi Alsoruji, Asmaa M. Khalil i Ahmed O. Mosleh. "Al 5251-based hybrid nanocomposite by FSP reinforced with graphene nanoplates and boron nitride nanoparticles: Microstructure, wear, and mechanical characterization". Nanotechnology Reviews 10, nr 1 (1.01.2021): 1752–65. http://dx.doi.org/10.1515/ntrev-2021-0108.
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Abstract The strength and wear resistance of aluminium alloys must be improved to enhance their usage in lightweight constructions. Thus, in this study, graphene nanoplates (GNPs) and boron nitride (BN) nanoparticles were reinforced into the Al 5251 aluminium alloy by friction stir processing (FSP). The Al 5251 aluminum alloy sheets were patterned with holes and filled by mono GNPs, mono BN nanoparticles and a hybrid of BN nanoparticles and GNPs. The microstructure, wear, and mechanical properties of the as-received, after FSP, and the manufactured surface nanocomposites were analysed. Wear tests were performed using two methods: weight loss and volume loss methods. FSP led to four times grain refinement. Due to the Zener pinning effect, the reinforcement nanoparticles improved the grain refinement effect by seven times decrease in the mean grain size. The wear rate by volume and weight loss with reinforcing BN nanoparticles decreased by 160 and 1,340%, respectively. Note that the GNP reinforcement insignificantly improved the wear resistance and hardness compared with the BN nanoparticles. The hardness was increased by 50, 120, and 80% by reinforcing the Al 5251 alloy with GNPs, BN, and a hybrid of BN nanoparticles and GNPs, respectively. The nanocomposite reinforced with GNPs exhibited superior mechanical properties compared to the other nanocomposites.
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Mohamed, Rhiyaad, Ziba Shabir Hussein Somjee Rajan, Julie-Ann Hoffman, Genevieve Moss, Lluis Solà-Hernàndez i Darija Susac. "(Invited) Towards the Development of High-Performance Crystalline Rutile Iridium Dioxide Electrocatalysts for the Oxygen Evolution Reaction". ECS Meeting Abstracts MA2022-02, nr 44 (9.10.2022): 1644. http://dx.doi.org/10.1149/ma2022-02441644mtgabs.
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Proton exchange membrane water electrolysis (PEMWE) offers a promising route for the production of green hydrogen from renewable energy sources and could be the master key to unlocking a future sustainable energy system (1). One of the main barriers delaying the wide-spread adoption of PEMWE technologies is the slow kinetics of the oxygen evolution reaction (OER) occurring at the anode and the need for high-cost, low-abundance precious metal electrocatalysts. Iridium-based oxides are still considered the only feasible option for practical applications due to their high activity and considerable corrosion stability under the harsh electrochemical reaction conditions. To improve the overall efficiency of PEMWEs, future electrocatalyst development strategies must concomitantly address performance metrics in terms of activity, stability and material cost. Towards enhancing iridium utilisation, efforts are aimed at increasing the electrochemical surface area of the catalyst per mass of iridium, thereby increasing the number of available electrocatalytic surface sites. In this regard, amorphous iridium oxide (IrOx) nanoparticles have been shown to achieve a high intrinsic activity (2). However, this comes at the expense of catalyst stability (3) and a loss of intrinsic electronic conductivity (4) associated with the lower degree of crystallinity. By maximising the dispersion of Ir-based nanoparticles, the use of high surface area support materials have also been shown to improve OER performance (5, 6). However, to address long-term stability concerns for Ir-based OER catalysts, highly crystalline rutile iridium dioxide (IrO2) materials may still offer the best prospects. The drawback of using this approach is that the formation of crystalline IrO2 nanoparticles often involves high temperature thermal oxidative treatment causing particle growth and loss of surface area, ultimately leading to decreased OER activities (7). Therefore, novel synthesis methods that retain a high degree of crystallinity without a loss of surface area for IrO2 nanoparticles are required. In this talk, we discuss two synthesis strategies geared towards the preparation of highly crystalline IrO2 nanoparticles with high OER performance. Firstly, we present a novel wet-chemistry synthesis method that avoids the use of reducing agents and eliminates the need for high temperature thermal oxidative treatment. The resultant nano-sized IrO2 nanoparticles were found to have excellent Ir mass-specific OER activity and durability attributed to the small nanoparticle size and high degree of crystallinity. Secondly, we present a novel metalorganic chemical deposition process as a simple, one-step preparation method for highly crystalline IrO2 nanoparticles supported on Sb-doped tin oxide (ATO) (8). The superior OER performance was attributed to the epitaxial anchoring of well dispersed, crystalline IrO2 nanoparticles onto the ATO support. We further discuss the versatility of the method to the application of other conductive oxide support materials such as indium tin oxide and F-doped tin oxide, with the ability of tuning the chemical state of the Ir-based nanoparticles by changing the reaction conditions, i.e., temperature and gas environment as well as the nature of the support. Finally, using a series detailed physico-chemical characterisation techniques to elucidate the nature the iridium phase, composition, morphology and structure, we relate these properties to the electrochemical activity and stability of the prepared materials for the OER. Herein, we highlight some of the challenges often encountered with the analysis of physical and electrochemical characterisation data for IrO2 nanoparticles, particularly when supported on other oxide materials. Acknowledgements This work is funded by the Department of Science and Innovation (DSI, South Africa) Impala Platinum Holdings Limited (Implats) and the Federal Minister of Education and Research (BMBF, Germany). References K. Ayers, Current Opinion in Electrochemistry, 18, 9 (2019). T. Reier, I. Weidinger, P. Hildebrandt, R. Kraehnert and P. Strasser, ECS Transactions, 58, 39 (2013). T. Binninger, R. Mohamed, K. Waltar, E. Fabbri, P. Levecque, R. Kötz and T. J. Schmidt, Scientific Reports, 5, 12167 (2015). M. Bernt, C. Schramm, J. Schröter, C. Gebauer, J. Byrknes, C. Eickes and H. A. Gasteiger, Journal of The Electrochemical Society, 168, 084513 (2021). H.-S. Oh, H. N. Nong, T. Reier, A. Bergmann, M. Gliech, J. Ferreira de Araújo, E. Willinger, R. Schlögl, D. Teschner and P. Strasser, Journal of the American Chemical Society, 138, 12552 (2016). A. Hartig-Weiss, M. Miller, H. Beyer, A. Schmitt, A. Siebel, A. T. S. Freiberg, H. A. Gasteiger and H. A. El-Sayed, ACS Applied Nano Materials, 3, 2185 (2020). J. Quinson, Advances in Colloid and Interface Science, 303, 102643 (2022). Z. S. H. S. Rajan, T. Binninger, P. J. Kooyman, D. Susac and R. Mohamed, Catalysis Science & Technology, 10, 3938 (2020).
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Qin, Ying, Yongzheng Li, Ruijie Wu, Xiaodi Wang, Jinli Qin, Yingjuan Fu, Menghua Qin, Zhiwei Wang, Yongchao Zhang i Fengshan Zhang. "Bilayer Designed Paper-Based Solar Evaporator for Efficient Seawater Desalination". Nanomaterials 12, nr 19 (5.10.2022): 3487. http://dx.doi.org/10.3390/nano12193487.
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Solar desalination devices utilizing sustainable solar energy and the abundant resource of seawater has great potential as a response to global freshwater scarcity. Herein, a bilayered solar evaporator was designed and fabricated utilizing a facile paper sheet forming technology, which was composed of cellulose fibers decorated with Fe3O4 nanoparticles as the top absorbent layer and the original cellulose fibers as the bottom supporting substrate. The characterization of the cellulose fibers decorated with Fe3O4 nanoparticles revealed that the in situ formed Fe3O4 nanoparticles were successfully loaded on the fiber surface and presented a unique rough surface, endowing the absorber layer with highly efficient light absorption and photothermal conversion. Moreover, due to its superhydrophilic property, the cellulose fiber-based bottom substrate conferred ultra-speed water transport capability, which could enable an adequate water supply to combat the water loss caused by continuous evaporation on the top layer. With the advantages mentioned above, our designed bilayered paper-based evaporator achieved an evaporation rate ~1.22 kg m−2 h−1 within 10 min under 1 sun irradiation, which was much higher than that of original cellulose cardboard. Based on the simple and scalable manufacture process, the bilayered paper-based evaporator may have great potential as a highly efficient photothermal conversion material for real-world desalination applications.
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Liu, Rou-Jane, Peter A. Crozier, C. Michael Smith, Dennis A. Hucul, John Blackson i Ghaleb Salaita. "In SituElectron Microscopy Studies of the Sintering of Palladium Nanoparticles on Alumina during Catalyst Regeneration Processes". Microscopy and Microanalysis 10, nr 1 (22.01.2004): 77–85. http://dx.doi.org/10.1017/s1431927604040188.
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Sintering of a palladium catalyst supported on alumina (Al2O3) in an oxidizing environment was studied byin situtransmission electron microscopy (TEM). In the case of a fresh catalyst, sintering of Pd particles on an alumina surface in a 500 mTorr steam environment happened via traditional ripening or migration and coalescence mechanisms and was not significant unless heating above 500°C. After the catalyst was used for the hydrogenation of alkynes, TEM coupled with convergent beam electron diffraction and electron energy loss spectroscopy analysis revealed that most of the Pd particles were lifted from the alumina surface by hydrocarbon buildup. This dramatically different morphology totally changed the sintering mechanism of Pd particles during the regeneration process. Catalytic gasification of hydrocarbon around these particles in an oxidizing environment allowed the Pd particles to move around and coalesce with each other at temperatures as low as 350°C. For catalysts heating under 500 mTorr steam at 350°C, steam stripped hydrocarbon catalytically at the beginning, but the reaction stopped after 4 h. Heating in air resulted in both catalytic and noncatalytic stripping of hydrocarbon.
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Kalashnikov N.P. "Sputtering of metal atoms with the wake potential excited by an electron beam". Physics of the Solid State 64, nr 5 (2022): 507. http://dx.doi.org/10.21883/pss.2022.05.53507.282.
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The process of metal atoms sputtering during a corona discharge is considered. When an electron moves in a medium at some velocity, charge screening occurs with a delay in space and time, which leads to the emergence of a wake potential. The excited oscillations of the wake charge lead to the appearance of additional forces. The energy loss of a moving particle per unit path is determined by the work produced of the deceleration force that acts on the particle from the side of the wake potential it creates in the medium. The paper considers the effect of the wake potential on the ions (atoms) sputtering of the lattice matrix. A well-known expression is used for the wake potential excited by a charged particle moving with energy, greater than the Fermi energy. An expression for the sputtering cross-section of metal atoms under the action of the wake potential excited by the electron beam is obtained. It is shown that the result of sputtering does not depend on the charge sign of the incident particle (electron or ion). Keywords: corona discharge, nanoparticles, metal surface, inelastic scattering, wake potential.
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Jakeer, Shaik, Sathishkumar Veerappampalayam Easwaramoorthy, Seethi Reddy Reddisekhar Reddy i Hayath Thameem Basha. "Numerical and Machine Learning Approach for Fe3O4-Au/Blood Hybrid Nanofluid Flow in a Melting/Non-Melting Heat Transfer Surface with Entropy Generation". Symmetry 15, nr 8 (28.07.2023): 1503. http://dx.doi.org/10.3390/sym15081503.
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The physiological system loses thermal energy to nearby cells via the bloodstream. Such energy loss can result in sudden death, severe hypothermia, anemia, high or low blood pressure, and heart surgery. Gold and iron oxide nanoparticles are significant in cancer treatment. Thus, there is a growing interest among biomedical engineers and clinicians in the study of entropy production as a means of quantifying energy dissipation in biological systems. The present study provides a novel implementation of an intelligent numerical computing solver based on an MLP feed-forward backpropagation ANN with the Levenberg–Marquard algorithm to interpret the Cattaneo–Christov heat flux model and demonstrate the effect of entropy production and melting heat transfer on the ferrohydrodynamic flow of the Fe3O4-Au/blood Powell–Eyring hybrid nanofluid. Similarity transformation studies symmetry and simplifies PDEs to ODEs. The MATLAB program bvp4c is used to solve the nonlinear coupled ordinary differential equations. Graphs illustrate the impact of a wide range of physical factors on variables, including velocity, temperature, entropy generation, local skin friction coefficient, and heat transfer rate. The artificial neural network model engages in a process of data selection, network construction, training, and evaluation through the use of mean square error. The ferromagnetic parameter, porosity parameter, distance from origin to magnetic dipole, inertia coefficient, dimensionless Curie temperature ratio, fluid parameters, Eckert number, thermal radiation, heat source, thermal relaxation parameter, and latent heat of the fluid parameter are taken as input data, and the skin friction coefficient and heat transfer rate are taken as output data. A total of sixty data collections were used for the purpose of testing, certifying, and training the ANN model. From the results, it is found that the fluid temperature declines when the thermal relaxation parameter is improved. The latent heat of the fluid parameter impacts the entropy generation and Bejan number. There is a less significant impact on the heat transfer rate of the hybrid nanofluid over the sheet on the melting heat transfer parameter.
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Deng, Xuesong, Yahui Wang, Lifang Ma, Zhigang Li, Zongsheng Chen, Xiangyin Lv, Yajing Chang, Yi Liu i Jiaming Shi. "Construction of Dual-Shell Mo2C/C Microsphere towards Efficient Electromagnetic Wave Absorption". International Journal of Molecular Sciences 23, nr 23 (22.11.2022): 14502. http://dx.doi.org/10.3390/ijms232314502.
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Carbon-based carbides have attracted tremendous attention for electromagnetic energy attenuation due to their adjustable dielectric properties, oxidation resistance, and good chemical stability. Herein, we reasonably regulate the growth of dopamine hydrochloride on the surface of the Mo-glycerate (Mo-GL) microsphere and then transform the resultant Mo-polydopamine (Mo-PD) microsphere into a dual-shell Mo2C/C (DS-Mo2C/C) microsphere in a high-temperature pyrolysis process under an inert atmosphere. It is found that the pyrolysis temperature plays an important role in the graphitization degree of the carbon matrix and internal architecture. The fabrication of a dual-shell structure can be propitious to the optimization of impedance matching, and the introduction of Mo2C nanoparticles also prompts the accumulation of polarization loss. When the pyrolysis temperature reaches 800 °C, the optimized composite of DS-Mo2C/C-800 exhibits good EM absorption performance in the frequency range of 2.0–18.0 GHz. DS-Mo2C/C-800′s qualified bandwidth can reach 4.4 GHz at a matching thickness of 1.5 mm, and the integrated qualified bandwidth (QBW) even exceeds 14.5 GHz with a thickness range of 1.5–5.0 mm. The positive effects of the dual-shell structure and Mo2C nanoparticles on EM energy attenuation may render the DS-Mo2C/C microsphere as a promising candidate for lightweight and broad bandwidth EM absorption materials in the future.
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Shahidi, Maryamsadat, Omid Abazari, Parisa Dayati, Ali Bakhshi, Azam Rasti, Fateme Haghiralsadat, Seyed Morteza Naghib i Davood Tofighi. "Aptamer-functionalized chitosan-coated gold nanoparticle complex as a suitable targeted drug carrier for improved breast cancer treatment". Nanotechnology Reviews 11, nr 1 (1.01.2022): 2875–90. http://dx.doi.org/10.1515/ntrev-2022-0479.
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Abstract In the following research, we specifically assessed the feasibility of a novel AS-1411-chitosan (CS)-gold nanoparticle (AuNPs) delivery system to carry methotrexate (MTX) into the cancer cells. The designed system had a spherical shape with average size of 62 ± 2.4 nm, the zeta potential of −32.1 ± 1.4 mV, and released MTX in a controlled pH- and time-dependent manner. CS-AuNPs could successfully penetrate the breast cancer cells and release the therapeutic drug, and ultimately, be accumulated by the nucleolin-AS1411 targeting mechanism within the in vivo environment. The anticancer activity of MTX was attributed to the induction of mitochondria membrane potential loss and nuclear fragmentation, which leads to apoptotic death. Moreover, the cellular internalization confirmed the high potential in the elimination of cancer cells without notable cytotoxicity on non-target cells. Therefore, it was concluded that the AS1411-CS-AuNPs with considerable in vitro and in vivo results could be utilized as a favorable system for breast cancer treatment.
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Asaad, Mohammad Ali, Ghasan Fahim Huseien, Mohammad Hajmohammadian Baghban, Pandian Bothi Raja, Roman Fediuk, Iman Faridmehr i Fahed Alrshoudi. "Gum Arabic Nanoparticles as Green Corrosion Inhibitor for Reinforced Concrete Exposed to Carbon Dioxide Environment". Materials 14, nr 24 (19.12.2021): 7867. http://dx.doi.org/10.3390/ma14247867.
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The inhibiting effect of Gum Arabic-nanoparticles (GA-NPs) to control the corrosion of reinforced concrete that exposed to carbon dioxide environment for 180 days has been investigated. The steel reinforcement of concrete in presence and absence of GA-NPs were examined using various standard techniques. The physical/surface changes of steel reinforcement was screened using weight loss measurement, electrochemical impedance spectroscopy (EIS), atomic force microscopy and scanning electron microscopy (SEM). In addition, the carbonation resistance of concrete as well screened using visual inspection (carbonation depth), concrete alkalinity (pH), thermogravimetric analysis (TGA), SEM, energy-dispersive X-ray spectroscopy (EDX) and X-ray diffraction (XRD). The GA-NPs inhibitor size was also confirmed by transmission electron microscopy (TEM). The results obtained revealed that incorporation of 3% GA-NPs inhibitor into concrete inhibited the corrosion process via adsorption of inhibitor molecules over the steel reinforcement surface resulting of a protective layer formation. Thus, the inhibition efficiency was found to increase up-to 94.5% with decreasing corrosion rate up-to 0.57 × 10−3 mm/year. Besides, the results also make evident the presence of GA-NPs inhibitor, ascribed to the consumption of calcium hydroxide, and reduced the Ca/Si to 3.72% and 0.69% respectively. Hence, C-S-H gel was developed and pH was increased by 9.27% and 12.5, respectively. It can be concluded that green GA-NPs have significant corrosion inhibition potential and improve the carbonation resistance of the concrete matrix to acquire durable reinforced concrete structures.
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Subramani, Murugan, Song-Jeng Huang i Konstantin Borodianskiy. "Effect of SiC Nanoparticles on AZ31 Magnesium Alloy". Materials 15, nr 3 (28.01.2022): 1004. http://dx.doi.org/10.3390/ma15031004.
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Magnesium alloys are attractive for the production of lightweight parts in modern automobile and aerospace industries due to their advanced properties. Their mechanical properties are usually enhanced by the incorporation with reinforcement particles. In the current study, reinforced AZ31 magnesium alloy was fabricated through the addition of bulk Al and the incorporation of SiC nanoparticles using a stir casting process to obtain AZ31-SiC nanocomposites. Scanning electron microscope (SEM) investigations revealed the formation of Mg17Al12 lamellar intermetallic structures and SiC clusters in the nanocomposites. Energy dispersive spectroscopy (EDS) detected the uniform distribution of SiC nanoparticles in the AZ31-SiC nanocomposites. Enhancements in hardness and yield strength (YS) were detected in the fabricated nanocomposites. This behavior was referred to a joint strengthening mechanisms which showed matrix-reinforcement coefficient of thermal expansion (CTE) and elastic modulus mismatches, Orowan strengthening, and load transfer mechanism. The mechanical properties and wear resistance were gradually increased with an increase in SiC content in the nanocomposite. The maximum values were obtained from nanocomposites containing 1 wt% of SiC (AZ31-1SiC). AZ31-1SiC nanocomposite YS and hardness were improved by 27% and 30%, respectively, compared to AZ31 alloy. This nanocomposite also exhibited the highest wear resistance; its wear mass loss and depth of the worn surface decreased by 26% and 15%, respectively, compared to AZ31 alloy.
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Milazzo, Rachela G., Antonio M. Mio, Giuseppe D’Arrigo, Emanuele Smecca, Alessandra Alberti, Gabriele Fisichella, Filippo Giannazzo, Corrado Spinella i Emanuele Rimini. "Influence of hydrofluoric acid treatment on electroless deposition of Au clusters". Beilstein Journal of Nanotechnology 8 (18.01.2017): 183–89. http://dx.doi.org/10.3762/bjnano.8.19.
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The morphology of gold nanoparticles (AuNPs) deposited on a (100) silicon wafer by simple immersion in a solution containing a metal salt and hydrofluoric acid (HF) is altered by HF treatment both before and after deposition. The gold clusters are characterized by the presence of flat regions and quasispherical particles consistent with the layer-by-layer or island growth modes, respectively. The cleaning procedure, including HF immersion prior to deposition, affects the predominantly occurring gold structures. Flat regions, which are of a few tens of nanometers long, are present after immersion for 10 s. The three-dimensional (3D) clusters are formed after a cleaning procedure of 4 min, which results in a large amount of spherical particles with a diameter of ≈15 nm and in a small percentage of residual square layers of a few nanometers in length. The samples were also treated with HF after the deposition and we found out a general thickening of flat regions, as revealed by TEM and AFM analysis. This result is in contrast to the coalescence observed in similar experiments performed with Ag. It is suggested that the HF dissolves the silicon oxide layer formed on top of the thin flat clusters and promotes the partial atomic rearrangement of the layered gold atoms, driven by a reduction of the surface energy. The X-ray diffraction investigation indicated changes in the crystalline orientation of the flat regions, which partially lose their initially heteroepitaxial relationship with the substrate. A postdeposition HF treatment for almost 70 s has nearly the same effect of long duration, high temperature annealing. The process presented herein could be beneficial to change the spectral response of nanoparticle arrays and to improve the conversion efficiency of hybrid photovoltaic devices.
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Batterjee, Maha G., Arshid Nabi, Majid Rasool Kamli, Khalid Ahmed Alzahrani, Ekram Y. Danish i Maqsood Ahmad Malik. "Green Hydrothermal Synthesis of Zinc Oxide Nanoparticles for UV-Light-Induced Photocatalytic Degradation of Ciprofloxacin Antibiotic in an Aqueous Environment". Catalysts 12, nr 11 (2.11.2022): 1347. http://dx.doi.org/10.3390/catal12111347.
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The design and development of new cost-effective, clean, and efficient synthesis procedures for the synthesis of nanoparticles have recently become an intriguing research topic with broad implications. This study aimed to develop an eco-friendly biogenic method that uses minimum nontoxic chemicals to yield ZnO nanoparticles with enhanced capabilities for degradation of pharmaceutical by-products. The present study used black dried lemon peel aqueous extract as a biological stabilizing agent to prepare pure and stable zinc oxide nanoparticles (LP-ZnO NPs). The surface morphology, elemental composition, crystalline properties, size, optical properties, the role of functional groups in stabilization, capping, and the thermal stability of LP-ZnO NPs were investigated using scanning electron microscopy equipped with energy dispersive X-ray (SEM-EDX), X-ray diffraction (XRD), UV–visible diffuse reflectance spectroscopy (UV-DRS), PL, Fourier transform infrared (FTIR), Raman spectra, and thermogravimetric (TGA) analyses. Multiphoton resonances were observed in LP-ZnO NPs along the crystalline structure as per Raman analysis. The developed LP-ZnO NPs were thermally stable at an annealing temperature of 500 °C with a weight loss of 53%. Photodegradation of antibiotic ciprofloxacin was observed in the presence of UV light via LP-ZnO NPs (serving as photocatalyst). In addition, in optimal reaction media, the biogenic LP-ZnO NPs retained improved photocatalytic performance toward ciprofloxacin. Meanwhile, in the photodegradation process of CPI molecules via ZnO as a photocatalyst, the optimum catalytic dose, concentration of CIP molecules, and pH were attained at 10 mg, 2 × 10−5 M, and pH 8, respectively. The aim of this research work was to develop a simple, affordable photocatalytic technique for the photodegradation of antibiotics in aqueous media. The photocatalytic process was performed under different experimental conditions, including varying catalytic doses, ciprofloxacin concentrations, and pH of the reaction mixture.
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Shamsuddin, Mustaffa, Fazleen Kamaludin i Suhaila Borhamdin. "Biosynthesis of gold nanoparticles-peanut shell composite for catalytic reduction of methyl blue". Malaysian Journal of Fundamental and Applied Sciences 16, nr 2 (15.04.2020): 252–57. http://dx.doi.org/10.11113/mjfas.v16n2.1805.
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Gold nanoparticles (AuNPs) has been recognized as an active and effective catalyst for many organic transformations. Currently, there is a growing need to develop AuNPs synthesis process that avoids the use of toxic chemicals or high energy requirement. In this research, the aqueous Phaleria macrocarpa (Mahkota dewa) dried fruit extract was used in the biosynthesis of AuNPs immobilized on peanut shell powder. The peanut shell supported AuNPs was characterized by UV–visible spectroscopy (UV–Vis), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetry analysis (TGA), Nitrogen (N2) adsorption-desorption and atomic absorption spectroscopy (AAS) techniques. The biosynthesized AuNPs was characterized by the appearance of a surface plasmon resonance (SPR) band at 534 nm in the UV–Vis spectrum. The XRD, TEM and TGA analytical data of AuNPs/Peanut shell composite indicated that the AuNPs with face-centred cubic (fcc) crystalline shape, mostly spherical and average particle size of 20.00 ± 4.19 nm were well dispersed on the peanut shell powder support. The FTIR analysis suggested that the C=O and O-H groups in the peanut shell powder have strong affinity to bind and stabilize the AuNPs. The BET surface area of the AuNPs/Peanut shell composite catalyst determined is 35.39 m² g-1 while the BJH pore volume is 0.035 cm3 g-1 with pore diameter of 2.07 nm. AAS elemental analytical data showed the Au loading is 0.03 mmol per gram of catalyst. The catalytic performance of the AuNPs/Peanut shell composite was investigated for the reduction of aqueous methyl blue (MB) at room temperature. The reduction of MB obeyed a pseudo-first-order reaction with the highest rate constant of 0.124 min-1. The supported AuNPs/Peanut shell composite catalyst could be easily recovered and reused for at least three times without significant loss of activity
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Liu, Gao. "(Invited) Conducting Polymers As Dual Charge Conductors for Electrochemical Systems". ECS Meeting Abstracts MA2022-02, nr 1 (9.10.2022): 30. http://dx.doi.org/10.1149/ma2022-02130mtgabs.
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Electrically conductive polymers are a class of polymers, which can conduct electricity. Conductive polymers have found niche applications such as anti-statics. The electrochemical energy storage devices, especially lithium-ion rechargeable batteries, has grown significantly in the past two decades. Recently multifunctional conductive polymers have been designed as dual ion and electron transport materials, and synthesized through a thermal process. These class of dual charge conducting polymers play a significant role as electrode binders for Silicon (Si) and Tin (Sn) alloy based anode electrode. Si is an attractive candidate for lithium-ion batteries because it delivers 10 times greater theoretical (∼4200 mAh/g) specific capacity than that of a traditional graphite anode (∼370 mAh/g). However, the widespread application of silicon materials has remained a significant challenge because of the large volume change during lithium insertion and extraction processes, disrupting both the Si electrode surface and electrode mechanical integrity. This large volume change causes electrode failure, leading to loss of the electrical contact and drastic capacity fading. Nanosizing the Si and Sn based anode materials provides better performance, but poses significant challenges to manufacturing of the electrode, including particle aggregation, and difficulties in maintaining constant electrical contacts to the nanoparticles, and excessive surface area. Conductive polymer binders can play multiple functions for Si electrode, including improved adhesion and connectivity, lithium ion compensation, better ion and electric conductivity as well as surface and interface modification. Organic and polymer chemistry has provided almost infinity possibilities to modify the polymeric binders to include the desired functionalities. This presentation will discuss the specific molecular design principles and synthetic steps to realize the structures and functionalities of the binders, how these binders interact with different alloy materials, and the electrochemical performances of the electrodes based on these binders.
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Couillard, Martin, Daniel D. Tyo, David M. Kingston, Bussaraporn Patarachao, Andre Zborowski, Samson Ng i Patrick H. J. Mercier. "Structure and Mineralogy of Hydrophilic and Biwettable Sub-2 µm Clay Aggregates in Oil Sands Bitumen Froth". Minerals 10, nr 11 (21.11.2020): 1040. http://dx.doi.org/10.3390/min10111040.
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A primary concern of commercial mined oil sands operations is the extent to which one can minimize the content of water and solids contaminants in the solvent-diluted bitumen products resulting from the bitumen production processes. During bitumen production, particles of about 2 µm or less may be responsible for the stabilization of water-in-bitumen emulsions that form during aqueous extraction of bitumen and purification of bitumen froth subsequently during the froth treatment processes, thus leading to the presence of those contaminants in solvent-diluted bitumen products. In this study, we separate and analyze sub-2 µm clay solids isolated from typical bitumen froth fed to a froth treatment plant at a commercial mined oil sands operation. Analytical transmission electron microscopy (TEM) with spatially-resolved energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) demonstrate key differences in morphology and composition between sub-2 µm clay aggregates with two distinct wettability characteristics: hydrophilic vs. biwettable particle surfaces. In particular, clay platelets with <200 nm lateral dimensions and thicknesses of a few atomic layers, which are intermixed within coarser sub-2 µm clay aggregates, are found to confer clear differences in morphological characteristics and wettability behaviors to the sub-2 µm clay aggregates. The <200 nm clay platelets found within sub-2 µm biwettable clays tend to arrange themselves with random orientations, whereas <200 nm clay platelets within sub-2 µm hydrophilic clays typically form well-ordered face-to-face stacks. Moreover, in biwettable sub-2 µm clay aggregates, <200 nm clay platelets often cover the surfaces of ~1–2 µm sized mineral particles, whereas similarly sized mineral particles in hydrophilic sub-2 µm clay aggregates, in contrast, generally have exposed surfaces without clay platelet coverage. These biwettable vs. hydrophilic behaviors are attributed to a difference in the surface characteristics of the <200 nm clay platelets caused by toluene-unextractable organic carbon coatings. Nanometer-scale carbon mapping reveals an inhomogeneous toluene-unextractable organic carbon coating on the surfaces of <200 nm platelets in biwettable clays. In contrast, hydrophilic clays have a significantly lower amount of toluene-unextractable organic carbon, which tends to be concentrated at steps or near metal oxide nanoparticles on clay particle surfaces. Mixing surface-active organic species, such as asphaltene, resin, or carboxylic organic acids of various types with inorganic solids can lead to a dramatically enhanced emulsion stability. Consequently, understanding the origin and characteristics of sub-2 µm clay solids in bitumen froth is important to (i) clarify their potential role in the formation of stable water-in-oil emulsions during bitumen production and (ii) improve froth treatment process performance to further reduce contaminant solids in solvent-diluted bitumen products. We discuss the implications of our results from these two perspectives.
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Irum, Samra, Nyla Jabeen, Khawaja Shafique Ahmad, Saima Shafique, Talha Farooq Khan, Hina Gul, Sadaf Anwaar, Nuzhat Imam Shah, Ansar Mehmood i Syed Zaheer Hussain. "Biogenic iron oxide nanoparticles enhance callogenesis and regeneration pattern of recalcitrant Cicer arietinum L." PLOS ONE 15, nr 12 (1.12.2020): e0242829. http://dx.doi.org/10.1371/journal.pone.0242829.
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This study is the first report on the biosynthesized iron oxide nanoparticles (IONPs) which mediate in-vitro callus induction and shoot regeneration in economically important recalcitrant chickpea crop (Cicer arietinum L.). Here, we used leaf extract of Cymbopogon jwarancusa for the synthesis of IONPs in order to achieve a better biocompatibility. The bioactive compounds in C. jwarancusa leaf extract served as both reducing and capping agents in the fabrication process of IONPs. Field emission scanning electron microscopy (FE-SEM) revealed rods like surface morphology of IONPs with an average diameter of 50±0.2 nm. Energy-dispersive X-ray spectroscopy (EDS) depicted formation of pure IONPs with 69.84% Fe and 30.16% O2. X-ray diffractometry (XRD) and attenuated total reflectance-fourier transform infrared (ATR-FTIR) validate the crystalline structure, chemical analysis detect the presence of various biomolecular fingerprints in the as synthesized IONPs. UV-visible absorption spectroscopy depicts activity of IONPs under visible light. Thermo-gravimetric analysis (TGA) displayed thermal loss of organic capping around 500°C and confirmed their stabilization. The biosynthesized IONPs revealed promising results in callus induction, shoot regeneration and root induction of chickpea plants. Both chickpea varieties Punjab-Noor 09 and Bittle-98 explants, Embryo axes (EA) and Embryo axes plus adjacent part of cotyledon (EXC) demonstrated dose-dependent response. Among all explants, EXC of Punjab-Noor variety showed the highest callogenesis (96%) and shoot regeneration frequency (88%), while root induction frequency was also increased to 83%. Iron content was quantified in regenerated chickpea varieties through inductively coupled plasma-optical emission spectrometry. The quantity of iron is significantly increased in Punjab-Noor regenerated plants (4.88 mg/g) as compare to control treated plants (2.42 mg/g). We found that IONPs enhance chickpea growth pattern and keep regenerated plantlets infection free by providing an optimum environment for rapid growth and development. Thus, IONPs synthesized through green process can be utilized in tissue culture studies in other important recalcitrant legumes crops.
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Lu, Yaqing, Yuyao Liu, Yujie Tong, Huili Cheng, Di Yang, Jiandong Ding i Qiyang Guo. "The Improved DC Breakdown Strength Induced by Enhanced Interaction between SiO2 Nanoparticles and LLDPE Matrix". Molecules 28, nr 13 (22.06.2023): 4908. http://dx.doi.org/10.3390/molecules28134908.
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Direct current (DC) power transmission systems have received great attention because it can easily integrate many types of renewable energies and have low energy loss in long-distance and large-capacity power transmission for electricity global sharing. Nanoparticles (NPs) have a positive effect on the insulation properties of polymers, but weak interaction between NPs and polymer matrix greatly decreases the effort of NPs on the enhancement of insulation properties, and thereby limits its engineering application. In this work, grafting strategy was used to link the modified NPs and polymer matrix to improve their interactions. Silica NPs (SiO2-NPs) were modified by 3-(methacrylyloxy) propyl-trimethoxysilane (MPS) to introduce highly active groups on the SiO2-NPs surface, followed by the pre-irradiated linear low-density polyethylene (LLDPE) being easily grafted onto the MPS modified SiO2-NPs (MPS-SiO2-NPs) in the melt blending process to obtain LLDPE-g-MPS-SiO2-NPs nanocomposites. Fourier-transform infrared (FT-IR) spectrum and X-ray photoelectron spectroscopy (XPS) confirm the successful incorporation of MPS into SiO2-NPs. Transmission electron microscopy (TEM) verifies that the modified SiO2-NPs exhibits more uniform distribution. The rheology result shows that the interaction between MPS-SiO2-NPs and LLDPE significantly improves. More importantly, the LLDPE-g-MPS-SiO2-NPs nanocomposites displays superior DC breakdown strength to that fabricated by conventional modification methods. When the addition of MPS-SiO2-NPs is 0.1 wt%, the highest DC breakdown strength values of 525 kV/mm and 372 kV/mm are obtained at 30 °C and 70 °C, respectively, and high DC breakdown strength can be well maintained in a wide loading range of NPs.
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Chen, Nancy, Morteza Sabet, Nawraj Sapkota, Craig M. Clemons, Apparao M. Rao i Srikanth Pilla. "Porous Silicon Nano-Quill Anodes for Lithium-Ion Batteries". ECS Meeting Abstracts MA2022-02, nr 4 (9.10.2022): 360. http://dx.doi.org/10.1149/ma2022-024360mtgabs.
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The growing population and increasing demands for energy are overwhelming our supply of fossil fuels and limiting the availability for future generations. Technologies for energy storage devices are emerging to replace conventional fuel-based technologies to meet emissions goals set by world governments and the rapid electrification of the transportation sector. Lithium-ion batteries (LIBs) are widely used for energy storage in devices across many commercial applications. LIB electrodes are continuously evolving due to demands for higher energy density and long cycling life. Among the recent developments in anode electrode materials, silicon (Si) is regarded as the most promising replacement for graphite due to its high theoretical specific capacity (~4200 mAh g-1), which is over 10 times greater than that of conventional graphite anodes (~372 mAh g-1). Despite the advancements, persisting challenges hinder the commercialization of Si for LIB anodes. Si-based electrodes are susceptible to rapid degradation due to the large volume change (approx. 400%) of Si particles during lithium insertion and extraction. The repeated volume change leads to the pulverization of the Si material, ultimately leading to decreased cycling stability from the loss of contact with the current collector. To overcome this obstacle, 3-dimensional porous and hollow nanostructures have been employed to provide sufficient void space to accommodate the volume change during electrochemical cycling. However, with the demands for material cost-reduction from industry, Si structures' strategic engineering must be cost-effective for commercial viability. Our team has developed a patent-pending cost-effective, scalable, and green methodology to use bio-renewable templates to synthesize a 3-dimensional Si architecture, called Si nano-quills (SiNQs). We innovated a two-step, cost-effective process that yields SiNQs with a porous morphology and hollow interior structure. First, in a scalable sol-gel process, silica gel particles were prepared using commonly available low-cost chemicals. The unique mesoporous SiNQ morphology was engineered using surfactant-modified cellulose nanocrystals as a bio-renewable sacrificial template. The templates were removed via thermal treatment to form silica nanoparticles. These particles, called silica nano-quills (SilicaNQs), possess a 3-dimensional bulk structure comprised of hollow quill-like arms and a high degree of porosity. In the second step, we employed a low-temperature magnesiothermic reduction method to convert SilicaNQs into SiNQs with a relatively large surface area. Anode electrodes were fabricated using SiNQs as the active material for electrochemical testing. The slurry was prepared using the active material, carbon black, and PVDF with a mass ratio of 60:20:20 coated onto an ion-permeable Bucky Paper (BP, a flexible and conductive paper made of carbon nanotubes). The 2032-type coin cells were assembled for battery testing using SiNQ electrodes (with an active mass loading of 1 mg cm-2) and a lithium metal chip as the counter electrode. The coin cells were cycled at a current rate of 0.1C (420 mA g-1) over the potential range of 0.01 – 1.0 V at room temperature. The SiNQ anode offered superior battery capacity retention of 73% of the initial reversible capacity of 963 mAh g-1 after 220 cycles. In comparison, batteries fabricated from the Mg reduction of commercially available mesoporous silica, SBA-15, offer capacity retention of only 52.6% after 100 cycles. The SiNQ precursor is engineered to possess porous walls with a superior BET surface area (1265 m2 g-1) compared to SBA-15 (550 m2 g-1). After Mg reduction, the SiNQs retain a BET surface area of 232 m2 g-1, whereas the surface area of reduced SBA-15 is 74 m2 g-1. The superior performance of SiNQs is due to their unique morphology that offers high surface area and porosity for effective diffusion of lithium ions and more sites for interactions with lithium ions, leading to a higher reversible capacity. Moreover, the porous architecture of SiNQs can effectively mitigate the volume change issue during lithiation and delithiation processes, thus providing a good cycling performance.
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Fang, Ling, Shun Lu i Hong Liu. "Electrocatalytic Nitrate Reduction to Ammonia By Oxide-Derived Copper with Stacking Faults". ECS Meeting Abstracts MA2022-02, nr 54 (9.10.2022): 2031. http://dx.doi.org/10.1149/ma2022-02542031mtgabs.
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The significant change of nitrogen cycle as a result of growing production and industrial use of nitrogen fertilizers has led to great environmental concern. The nitrate (NO3 -) in groundwater and industrial wastewater pose a serious threat to the nitrogen cycle and human health, which creates a need for efficient methods that can convert nitrate species. Although many techniques such as biological denitrification, ion exchange, reverse osmosis, and electrodialysis have been developed for NO3 --rich water remediation, electrocatalytic nitrate reduction reaction (NO3RR) is a promising technology that utilize electricity from renewable solar/wind energies to selectively reduce NO3 - to nitrogen (N2) or ammonia (NH3). Of note that NH3 is a fertilizer source and is also considered as a green hydrogen-rich fuels. Therefore, converting NO3 - in wastewater to recyclable NH3 is attractive with regard to environmental protection and energy saving. Metal oxide catalysts with well-controlled shape and size are currently developed to explore catalytic performance trends and intrinsic mechanism for the NO3RR. For example, Co3O4-based nanoparticles and nanosheet array exhibit improved performance because of the optimized exposed surface and size distribution. TiO2 nanotube arrays with anatase structure displayed better electrocatalytic activity than those with rutile structure. These findings have demonstrated that metal oxide catalysts with subtle composition and crystal structure play an important role in enhanced performance for the NO3RR. However, the redox potential for metal oxide reduction is more positive than the potential required for the NO3RR, so metal oxides can be further reduced to metal state under NO3RR. During the reduction process, the loss of structural oxygen ions in metal oxide catalyst would lead to its nonstoichiometry. Accordingly, the electrochemical reduction conditions may drive the generation of defects to accommodate the nonstoichiometry. Therefore, we hypothesized that the substantial structural perturbations such as dislocations could induce lattice strains in the defect region. Such lattice strains will modulate the local surface electronic structure of the catalysts, tuning the interaction between the reaction species and catalyst surface. As a result, the catalytic activity of metal oxides could be optimized. In this study, we selected Cu-based oxide electrodes to fully investigate the structural change and its effects on catalytic performance towards NO3RR. We found that Cu oxide catalysts have a distinct structural change during the NO3RR. The Cu oxide catalysts were reduced to metallic Cu under the negative potential of NO3RR, which serves as the actual active species. More importantly, we found that abundant stacking faults were formed on the oxide-derived Cu surfaces due to the applied negative potential during the NO3RR or the electroreduction pretreatment. The in situ electrochemical reduction-generated stacking faults can be utilized to increase NO3 --N removal, NH4 +-N selectivity, and NH3 Faradaic efficiency up to 93, 94, and 80%, respectively. On the basis of theoretical and experimental investigations, it is concluded that the tensile strain resulting from the stacking faults facilitates NO3 - adsorption and suppresses hydrogen evolution reaction. This work not only helps explain the improved reactivity of related metal oxide for the NO3RR, but also provides a general strategy to develop active and stable electrocatalysts with rational designed surface structure. Figure 1
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Hossain, Md Asjad, Morteza Javadi, Haoyang Yu, Alyxandra N. Thiessen, Nduka Ikpo, Anton O. Oliynyk i Jonathan G. C. Veinot. "Dehydrocoupling – an alternative approach to functionalizing germanium nanoparticle surfaces". Nanoscale 12, nr 11 (2020): 6271–78. http://dx.doi.org/10.1039/c9nr10837h.
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Schematic representation of dehydrocoupling of H-GeNPs with alkylsilanes, and Electron Energy Loss Spectroscopy (EELS) line scan of alkylsilane passivated GeNPs showing Si on the surface and Ge in the core.
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Hopf, Alexander, Jacopo De Bellis, Timo Imhof, Norbert Pfänder, Marc Ledendecker i Ferdi Schüth. "Facile Solid-State Synthesis of Supported Ptm-Nps for the Oxygen Reduction Reaction". ECS Meeting Abstracts MA2022-01, nr 35 (7.07.2022): 1453. http://dx.doi.org/10.1149/ma2022-01351453mtgabs.
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Supported bimetallic catalysts composed of platinum and transition metals are highly investigated electrocatalysts for the oxygen reduction reaction (ORR) because of their enhanced activity and stability. However, common routes to synthesize these materials are often laborious and not scalable, employing organic solvents or uneconomical metal deposition methods [1-2]. Here, we present a mechanochemistry-assisted, dry and scalable synthesis route towards supported bimetallic catalysts, which consists of only two steps: First, metal salts are dispersed on a carbon support in a planetary mill without further additives. Following, the powder is reduced with hydrogen and annealed to yield alloyed catalysts. With this process, we are able to synthesize PtM/C catalysts where M was Ni, Co or Ru. Both metal loading and ratio could be adjusted by changing the amount of metal salt. The average size of the PtM-NPs was similarly controlled by changing the annealing temperature. With X-ray diffraction (XRD), we show that no metal or salt reflexes are present after milling and that the XRD pattern matches the carbon support. After reduction and annealing, clear reflexes of the targeted alloy composition are visible. The latter was confirmed by scanning transmission electron microscopy coupled with energy dispersive X-ray spectroscopy (STEM-EDX). After milling, ionic metal species are present as sub-nanometer clusters evenly dispersed over the carbon support. After reduction and annealing, PtM nanoparticles have formed. Neither by XRD nor by STEM-EDX was the presence of unalloyed Pt or M detected. Optical emission spectrometry was used to confirm the targeted loading and bulk composition of the catalysts. Due to the known high activity for catalyzing the ORR, PtNi/C and PtCo/C were subjected to electrochemical evaluation in a rotating disc electrode setup [2]. In both cases, specific activities surpassing 1 mA/cm2 Pt at 0.9 V were reached. The electrochemically active surface area (ECSA) and mass activity were also in the range expected for the composition and particle size. To assess the stability, the catalysts were cycled from 0.4 to 1.0 V (RHE) with a scan rate of 1 V/s for 10800 cycles. The loss in ECSA of approximately 5 % was also in line with expectations. Since iron impurities are known to reduce the lifetime of a proton exchange membrane fuel cell, the milling process was adapted to a Si3N4-mill instead of a steel mill, again demonstrating the flexibility of this synthesis route [3]. To conclude, the reported solid-state procedure allows the dry synthesis of supported bimetallic catalysts over a wide range of compositions. The materials show high activity and stability catalyzing the ORR. Due to its simplicity and flexibility, we expect this synthesis approach to be applied in other fields of catalysis within a short period of time. References: [1] K. Loza, M. Heggen, M. Epple, Adv. Funct. Mater., 2020, 30, 1909250. [2] I. E. L. Stephens, A. S. Bondarenko, U. Grønbjerg, J. Rossmeisl and I. Chorkendorff, Energy Environ. Sci., 2012, 5, 6744. [3] A. Collier, H. Wang, X. Z. Yuan, J. Zhang, D. P. Wilkinson, Int. J. Hydrog. Energy, 2006, 31, 1838–1854. [4] J. De Bellis, M. Felderhoff, F. Schüth, Chem. Mater., 2021, 33, 6, 2037–2045. Figure 1
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Brenier, R. "Silver Nanoparticle Oxide Coating via a Surface-Initiated Reduction Process". Journal of Physical Chemistry C 113, nr 5 (13.01.2009): 1758–63. http://dx.doi.org/10.1021/jp808860n.
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Jing, Chao, Zhen Gu, Tao Xie i Yi-Tao Long. "Color-coded imaging of electrochromic process at single nanoparticle level". Chemical Science 7, nr 8 (2016): 5347–51. http://dx.doi.org/10.1039/c6sc00903d.
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Based on a plasmon resonance energy transfer (PRET) method, the electrochromic process was imaged in real-time under potential scanning, which achieved the detection of hundreds of molecules on the surface of a single nanoparticle with high time-spatial resolution.
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Kim, Hong Soo, Hwapyong Kim, Monica Claire Flores, Gyu-Seok Jung i Su-Il In. "Stable Surface Technology for HER Electrodes". Catalysts 11, nr 6 (30.05.2021): 693. http://dx.doi.org/10.3390/catal11060693.
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With the rapid increase in energy consumption worldwide, the development of renewable and alternative energy sources can sustain long-term development in the energy field. Hydrogen (H2), which is one of the clean chemical fuels, has the highest weight energy density and its combustion byproduct is only water. Among the various methods of producing hydrogen source, water electrolysis is a process that can effectively produce H2. However, it is difficult for commercialization of water electrolysis for H2 production due to the high cost and low abundance of noble metal-based cathodic electrode used for highly efficiency. Several studies have been conducted to reduce noble metal loading and/or completely replace them with other materials to overcome these obstacles. Among them, stainless steel contains many components of transition metals (Ni, Cr, Co) but have sluggish reaction kinetics and small active surface area. In this study, the problem of stainless steel was to be solved by utilizing the electrocatalytic properties of silver nanoparticles on the electrode surface, and electrodes were easily fabricated through the electrodeposition process. In addition, the surface shape, elemental properties, and HER activity of the electrode was analyzed by comparing it with the commercialized silver nanoparticle-coated invasive electrodes from Inanos (Inano-Ag-IE) through the plasma coating process. As a result, silver nanoparticle-coated conventional electrode (Ag-CE) fabricated through electrodeposition confirmed high HER activity and stability. However, the Inano-Ag-IE showed low HER activity as silver nanoparticles were not found. We encourage further research on the production process of such products for sustainable energy applications.
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SINGH, NAVINDER. "HOT ELECTRON RELAXATION IN A METAL NANOPARTICLE: ELECTRON SURFACE-PHONON INTERACTION". Modern Physics Letters B 18, nr 24 (20.10.2004): 1261–65. http://dx.doi.org/10.1142/s0217984904007797.
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The relaxation of hot electrons is considered in a metal nanoparticle. When the particle size is of the order of electron mean free path, the main channel of hot electron energy loss is through surface-phonon generation, rather than bulk phonon generation. A calculation for the hot electron relaxation by the generation of surface-phonons is given, assuming that electrons and surface-phonons are described by their equilibrium Fermi and Bose distribution functions. The assumption is valid because the time required to establish equilibrium in the electron gas is much less than the time for achieving equilibrium between the electrons and the surface-phonons. The expressions obtained for low-temperature and high-temperature regimes are inversely proportional to the radius of the particle. This shows that size dependency of electron surface-phonon energy exchange arises from the geometric effect.
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Valentini, Paolo, i Traian Dumitrica. "Molecular Dynamics Simulations of Nanoparticle-Surface Collisions in Crystalline Silicon". Journal of Nano Research 1 (styczeń 2008): 31–39. http://dx.doi.org/10.4028/www.scientific.net/jnanor.1.31.
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We present a microscopic description for the impacting process of silicon nanospheres onto a silicon substrate. In spite of the relatively low energy regime considered (up to 1 eV/atom), the impacting process exhibits a rich behavior: A rigid Hertzian model is valid for speeds below 500 m/s, while a quasi-ellipsoidal deformation regime emerges at larger speeds. Furthermore, for speeds up to 1000 m/s the particle undergoes a soft landing and creates a long-lived coherent surface phonon. Higher speeds lead to a rapid attenuation of the coherent phonon due to a partial diamond cubic to-tin phase transformation occurring in the particle.
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Colliex, C., K. Suenaga, M. Kociak i O. Stephan. "Valence Electron EELS Spectroscopy on Nanoparticle Surfaces". Microscopy and Microanalysis 5, S2 (sierpień 1999): 668–69. http://dx.doi.org/10.1017/s1431927600016664.
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A series of recent experiments, using electron as well as photon probes [1-3], have attracted considerable interest on the importance of surface plasmon modes in nanostructured media such as nanospheres, nanotubes, nanowires, nanopores or nanoholes.The basic principle for STEM operation had early been recognized to be well suited to the investigation of cases where non penetrating electrons propagate at a given impact parameter from an external surface (along "aloof7 trajectories, using a terminology proposed by Warmack et al. [4]). One of the most spectacular effect is that signals attributed to the excitation of-surface plasmon modes could be detected in vacuum at distances as large as a few tens of nanometers from the outside surface of a specimen, see for instance [5] for the planar geometry and [6], for the spherical one. Most interpretations accounting for the spatial dependence of EELS spectra in the "aloof geometries, rely on models using the bulk dielectric coefficients of the material to describe the induced charges and polarization responsible for the specimen electric field acting on the probe electron and consequently for the measured energy loss.
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Hong, Ying-Jhan, Lin-Ai Tai, Hung-Jen Chen, Pin Chang, Chung-Shi Yang i Tri-Rung Yew. "Stable water layers on solid surfaces". Physical Chemistry Chemical Physics 18, nr 8 (2016): 5905–9. http://dx.doi.org/10.1039/c5cp07866k.
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A water layer adhered to a microchannel wall is 100 to 170 nm thick and stable against surface tension. The water layer thickness was measured using electron energy loss spectroscopy (EELS), and the water layer structure was characterized by using a quantitative nanoparticle counting technique.
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Yin, Zhao-Qin, i Ming Lou. "Experimental study on nanoparticle deposition in straight pipe flow". Thermal Science 16, nr 5 (2012): 1410–13. http://dx.doi.org/10.2298/tsci1205410y.
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Loss of the number of nanoparticles within pipe may lead to significant change of particle number distribution, total mass concentration and particles mean size. The experiments of multiple dispersion aerosol particles ranging from 5.6 nm to 560 nm in straight pipe are carried out using a fast mobility particle sizer. The particle size number distribution, total number concentrations, geometric mean size and volume are acquired under different pipe lengths and Reynolds numbers. The results show lengthening the pipe and strengthening the turbulence can promote the particle deposition process. The penetration efficiency of smaller particle is lower than the larger one, so the particle mean size increases in the process of deposition.
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Fujiyoshi, Yoshifumi, Takashi Nemoto i Hiroki Kurata. "Studying substrate effects on localized surface plasmons in an individual silver nanoparticle using electron energy-loss spectroscopy". Ultramicroscopy 175 (kwiecień 2017): 116–20. http://dx.doi.org/10.1016/j.ultramic.2017.01.006.
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TÖKÉSI, K., L. KÖVÉR, D. VARGA, J. TÓTH i T. MUKOYAMA. "EFFECTS OF SURFACE LOSS IN REELS SPECTRA OF SILVER". Surface Review and Letters 04, nr 05 (październik 1997): 955–58. http://dx.doi.org/10.1142/s0218625x97001115.
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The energy distribution of the electrons backscattered in the direction of the surface normal of polycrystalline silver samples was studied using reflected electron energy loss spectroscopy (REELS) at 200 eV and 2 keV primary beam energies. For modeling the electron scattering processes, the Monte Carlo simulation technique was used and the REELS spectra were calculated at various (25°, 50° and 75°, with respect to the surface normal) angles of primary beam incidence. The effects of the surface energy loss process in REELS are evaluated from the comparison of the experimental and simulated spectra.
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Yuwono, Akhmad Herman, Nofrijon Sofyan, Vincentius Hamdani, Amalia Sholehah i Muhammad Arief. "The Effect of Precursor Mixing Temperature during Precipitation Process on the Size of ZnO Nanoparticles and the Dispersion of ZnO@SiO2 Core-Shell Nanostructure". Applied Mechanics and Materials 525 (luty 2014): 108–16. http://dx.doi.org/10.4028/www.scientific.net/amm.525.108.
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ZnO nanoparticles have been used for many applications, including in cell labeling application. Its light emission can be used to determine and identify biology cells. Wet chemical precipitation method has been successfully done to synthesize the nanoparticle and it was subsequently continued by encapsulating with silica to keep ZnO stabilized in water to be properly used in cell labeling application. Varying precipitation temperatures has been performed to control the nanoparticle size and the addition of F127 surface active agent was carried out to prevent the agglomeration. The results showed the smallest nanoparticle (3.49 nm) was obtained from the process with temperature of 25oC, with the highest band gap energy, 3.12 eV. On the other hand, the largest nanoparticle (13.16 nm) was obtained from synthesis at temperature of 65oC, with the lowest band gap energy, 3.08 eV. These levels of band gap energy are potentially suitable for cell labeling application.
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Majerič, Peter, Rebeka Rudolf i Ivan Anžel. "Thermodynamics of nanoparticles". Anali PAZU 4, nr 1 (7.06.2022): 28–33. http://dx.doi.org/10.18690/analipazu.4.1.28-33.2014.
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This article deals with the basis for thermodynamic calculations of nanoparticles. Thermodynamics on the nanoscale are different than in bulk form, as there are more surface atoms with surface energy, which is different from bulk atom energy. This contribution of surface energy in nanoparticles changes the mechanisms of melting, grain growth, etc. compared to bulk materials. Using this starting point, one can use these calculations as a basis in nanoparticle synthesis processes. In our research we have synthesized nanoparticles with the process known as Ultrasonic Spray Pyrolysis. This is a versatile process, capable of producing nanoparticles from various materials such as gold, silver, titanium dioxide, nickel, nickel titanium, and so on.
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Zhou, Jianwei, Meimei Guo, Yu Qin, Wenjun Wang, Ruiling Lv, Enbo Xu, Tian Ding, Donghong Liu i Zhengzong Wu. "Advances in Starch Nanoparticle for Emulsion Stabilization". Foods 12, nr 12 (20.06.2023): 2425. http://dx.doi.org/10.3390/foods12122425.
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Starch nanoparticles (SNPs) are generally defined as starch grains smaller than 600–1000 nm produced from a series of physical, chemical, or biologically modified starches. Many studies have reported the preparation and modification of SNPs, which are mostly based on the traditional “top-down” strategy. The preparation process generally has problems with process complexity, long reaction periods, low yield, high energy consumption, poor repeatability, etc. A “bottom-up” strategy, such as an anti-solvent method, is proven to be suitable for the preparation of SNPs, and they are synthesized with small particle size, good repeatability, a low requirement on equipment, simple operation, and great development potential. The surface of raw starch contains a large amount of hydroxyl and has a high degree of hydrophilicity, while SNP is a potential emulsifier for food and non-food applications.
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Thron, A. M., A. Polyakov, P. J. Shuck i S. Aloni. "Investigation of Surface Plasmon Coupling and Damping in Au and Ag Nanoparticle Assemblies by Monochromated Electron Energy Loss Spectroscopy". Microscopy and Microanalysis 20, S3 (sierpień 2014): 600–601. http://dx.doi.org/10.1017/s1431927614004723.
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Song, Xiaozong, i Gui Gao. "Removal Mechanism Investigation of Ultraviolet Induced Nanoparticle Colloid Jet Machining". Molecules 26, nr 1 (25.12.2020): 68. http://dx.doi.org/10.3390/molecules26010068.
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Ultraviolet induced nanoparticle colloid jet machining is a new ultra-precision machining technology utilizing the reaction between nanoparticles and the surface of the workpiece to achieve sub-nanometer ultra-smooth surface manufacturing without damage. First-principles calculations based on the density functional theory (DFT) were carried out to study the atomic material removal mechanism of nanoparticle colloid jet machining and a series of impacting and polishing experiments were conducted to verify the mechanism. New chemical bonds of Ti-O-Si were generated through the chemical adsorption between the surface adsorbed hydroxyl groups of the TiO2 cluster and the Si surface with the adsorption energy of at least −4.360 eV. The two Si-Si back bonds were broken preferentially and the Si atom was removed in the separation process of TiO2 cluster from the Si surface realizing the atomic material removal. A layer of adsorbed TiO2 nanoparticles was detected on the Si surface after 3 min of fixed-point injection of an ultraviolet induced nanoparticle colloid jet. X-ray photoelectron spectroscopy results indicated that Ti-O-Si bonds were formed between TiO2 nanoparticles and Si surface corresponding to the calculation result. An ultra-smooth Si workpiece with a roughness of Rq 0.791 nm was obtained by ultraviolet induced nanoparticle colloid jet machining.
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Zhang, Wenjie, Ali Hosseini Taleghani, M. Ayani, Mohammed Reza Hajizadeh i Houman Babazadeh. "Nanoparticle and shape factor for improving solidification rate". International Journal of Modern Physics C 31, nr 10 (6.08.2020): 2050141. http://dx.doi.org/10.1142/s0129183120501417.
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The main aim of this paper is to examine the discharging process with insertion of wavy surface and changing shape of nanoparticles. Contours were presented in the form of contours and profiles of energy and temperatures. To get the acceptable accuracy, adaptive grid is employed and time steps for each iteration are variable. The outputs indicate that augmenting A and selection of platelet shape lead to a faster solidification. With augment of [Formula: see text], 14% reduction has been reported for ([Formula: see text]). Such percentage augments with the rise of [Formula: see text] and 14.03% reduction were reported for ([Formula: see text]). At [Formula: see text], augmenting [Formula: see text] from 0.1 to 0.3 makes the time to reduce from 44.16[Formula: see text]s to 37.96[Formula: see text]s. Lower level of energy was reported for platelet shapes, which means higher liquid fraction of domain. Temperature declines with augment of [Formula: see text] and [Formula: see text] prolongs process of about 14.03% in the existence of platelet shape.
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Jeong, Heon Jun, Hyun Soo Park, Keun Hee Kim, Wanhyuk Chang, Yoon Seong Kim, Yun Sung Choi i Joon Hyung Shim. "Performance Improvement of Proton Ceramic Fuel Cells through Surface Treatment of Cobalt Oxide Nanoparticles on Perovskite Oxide". ECS Transactions 111, nr 6 (19.05.2023): 2155–60. http://dx.doi.org/10.1149/11106.2155ecst.
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This study reports on the performance improvement of a protonic ceramic fuel cell (PCFC) after a CoOx nanoparticle treatment has been applied to a PrBa0.5Sr0.5Co2-xFexO5+δ(PBSCF) cathode with a perovskite structure. CoOx nanoparticles are deposited on the sintered PBSCF surface using a plasma-enhanced (PE) atomic layer deposition (ALD) process, thereby avoiding any unwanted reactions or phase changes. The CoOx nanoparticles are successfully deposited uniformly onto the entire surface of the porous and complex cathode structure. A constant deposition rate is observed because of the self-limiting characteristics of the ALD process by a thickness difference as a function of a change in the cycle count. In our experiment, the performance of the fuel cells increases by approximately 36 % compared with the untreated cells at an operating temperature of 650 °C. In addition, all cells feature long-term stability. Impedance analysis reveals that the CoOx nanoparticle treatment results in a significant polarization and some ohmic loss improvement within all temperature regions. This is due to the synergistic effect with PBSCF and self-catalytic effects. The results imply that the proposed method enables high-performance PCFC fabrication; additionally it helps lowering the operating temperature.
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Li, Mingda, Wenping Cui, Lijun Wu, Qingping Meng, Yimei Zhu, Yong Zhang, Weishu Liu i Zhifeng Ren. "Topological effect of surface plasmon excitation in gapped isotropic topological insulator nanowires". Canadian Journal of Physics 93, nr 5 (maj 2015): 591–98. http://dx.doi.org/10.1139/cjp-2014-0418.
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We present a theoretical investigation of the surface plasmon (SP) at the interface between a topologically nontrivial cylindrical core and a topologically trivial surrounding material, from the axion electrodynamics and modified constitutive relations. We find that the topological effect always leads to a red-shift of SP energy, while the energy red-shift decreases monotonically as core diameter decreases. A qualitative picture based on classical perturbation theory is given to explain these phenomena, from which we also infer that to enhance the shift, the difference between the inverse of dielectric constants of two materials must be increased. We also find that the surrounding magnetic environment suppresses the topological effect. All these features can be well described by a simple ansatz surface wave, which is in good agreement with full electromagnetic eigenmodes. In addition, bulk plasmon energy at ωp = 17.5 ± 0.2 eV for a semiconducting Bi2Se3 nanoparticle is observed from high-resolution electron energy loss spectrum measurements.