Готові списки джерел за темами / Surface redox reduction

Добірка наукової літератури з теми "Surface redox reduction"

Автор: Grafiati

Опубліковано: 6 вересня 2023

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Статті в журналах з теми "Surface redox reduction"

Hua, Chunxia, Shuliang Dou, Hongbo Xu, Shuai Hou, Hangchuan Zhang, Panpan Zhang, Yang Gan, Jiupeng Zhao, and Yao Li. "A nanostructured Fc(COCH3)2film prepared using silica monolayer colloidal crystal templates and its electrochromic properties." Physical Chemistry Chemical Physics 19, no. 45 (2017): 30756–61. http://dx.doi.org/10.1039/c7cp05074g.

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Zhu, Yun Guang, Chuankun Jia, Jing Yang, Feng Pan, Qizhao Huang, and Qing Wang. "Dual redox catalysts for oxygen reduction and evolution reactions: towards a redox flow Li–O2 battery." Chemical Communications 51, no. 46 (2015): 9451–54. http://dx.doi.org/10.1039/c5cc01616a.

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Bradley, Kieren, Kyriakos Giagloglou, Brian E. Hayden, Hugo Jungius, and Chris Vian. "Reversible perovskite electrocatalysts for oxygen reduction/oxygen evolution." Chemical Science 10, no. 17 (2019): 4609–17. http://dx.doi.org/10.1039/c9sc00412b.

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Voylov, D. N., I. N. Ivanov, V. I. Bykov, S. B. Tsybenova, I. A. Merkulov, S. A. Kurochkin, A. P. Holt, A. M. Kisliuk, and A. P. Sokolov. "Oscillatory behaviour of the surface reduction process of multilayer graphene oxide at room temperature." RSC Advances 6, no. 81 (2016): 78194–201. http://dx.doi.org/10.1039/c6ra14414d.

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Heyrovský, Michael, and Ladislav Novotný. "Interfacial interactions and the heterogeneous one-electron reduction of methyl viologen." Collection of Czechoslovak Chemical Communications 52, no. 5 (1987): 1097–114. http://dx.doi.org/10.1135/cccc19871097.

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The one-electron reversible electroreduction of methyl viologen to its radical cation in aqueous solutions on mercury electrodes proceeds, according to potential, concentration and time of electrolysis, in various ways. Methyl viologen is adsorbed in flat orientation at the electrode surface; it undergoes a surface redox process in π-interaction with the metal in a potential range positive by about 0.2 V of the beginning of the electroreduction. The actual reduction starts by electron transfer followed by adsorption of the radical cation and, at higher concentrations and in a narrow potential range, by crystallization at the electrode surface of a salt of the radical cation. In solution near the electrode the radical cation dimerizes and the dimer also adsorbs at the electrode. In the region of the standard redox potential and more negative the reduction proceeds by electron transfer from the electrode covered by a layer of the radical cation or of its dimer.

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Whittingham, Alexander W. H., Jordan Lau, and Rodney D. L. Smith. "Mechanistic insights into the spontaneous reaction between CO2 and La2–xSrxCuO4." Canadian Journal of Chemistry 99, no. 9 (September 2021): 773–79. http://dx.doi.org/10.1139/cjc-2021-0059.

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Layered perovskites such as La2–xSrxCuO4 are active electrocatalysts for CO2 reduction, but they suffer from structural instability under catalytic conditions. This structural instability is found to arise from the reaction of CO2 with surface sites. Variable scan rate voltammetry shows the growth of a Cu-based redox couple when potentials cathodic of 0.6 V vs. RHE are applied in the presence of CO2. Electrochemical impedance spectroscopy identifies a redox active surface state at this voltage, whose concentration is increased by electrochemical reduction in the presence of CO2. In situ spectroelectrochemical FTIR identifies surface bound carbonates as being involved in the formation of these surface sites. The orthorhombic lattice for La2CuO4 is found to uniquely enable binding bidentate binding of carbonate ions to the surface through reaction with CO2. The incorporation of Sr(II) induces a transition to a tetragonal lattice, for which only monodentate carbonate ions are observed. It is proposed that the binding of carbonate ions in a bidentate fashion generates sufficient strain at the surface to result in amorphization at the surface, yielding the observed Cu(II)/Cu(I) redox couple.

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Andreeva, Donka Ch, Matey G. Kalchev, and Atanas A. Andreev. "Surface Redox Strength and Catalytic Activity of the CuO/ZnO System." Collection of Czechoslovak Chemical Communications 57, no. 12 (1992): 2561–64. http://dx.doi.org/10.1135/cccc19922561.

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Information about the reduction properties and reactivity of surface hydroxyl groups has been obtained from the interaction of iodine with a series of CuO/ZnO samples in wide range of concentrations. The maximum capacity of iodine reduction and maximum catalytic activity in water gas shift reaction were observed with the sample containing 20 wt.% CuO. The correlation found gives evidence in favour of the associative mechanism of reaction.

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Gross-Wittke, A., G. Gunkel, and A. Hoffmann. "Temperature effects on bank filtration: redox conditions and physical-chemical parameters of pore water at Lake Tegel, Berlin, Germany." Journal of Water and Climate Change 1, no. 1 (March 1, 2010): 55–66. http://dx.doi.org/10.2166/wcc.2010.005.

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In the city of Berlin, artificial groundwater recharge techniques, such as bank filtration and infiltration ponds, are an important source for drinking water production. Climate change with increasing surface water temperatures can influence the water purification processes during bank filtration mainly due the intensification of metabolic processes leading to a decrease of oxygen and an increase of anaerobic conditions. In Lake Tegel a significant increase of water temperature in the epilimnion of 2.4°C within the last 30 years was recorded. For a better understanding of induced bank filtration at Lake Tegel, redox processes and physical-chemical conditions within the surface sediment layers (0–26 cm depth) at the littoral infiltration zone were investigated. The influence of temperature in the range of 0–25°C on microbial catalysis of redox processes, such as reduction of nitrate and sulphate, was examined during the period March 2004–June 2005. High water temperatures (16–25°C) were accompanied by negative redox potentials (EH=−47 mV) and decreasing Ninorg concentrations, while the amount of ammonia, Mn2 + and Fe2 + was rising. This indicates redox processes such as denitrification, Mn4 + reduction, nitrate respiration and ammonification, as well as Fe3 + reduction. The reduction of sulphate, however, has not yet become significant at Lake Tegel, but with increasing water temperature, sulphate reduction must be expected.

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Vecchietti, Julia, Sebastián Collins, Wenqian Xu, Laura Barrio, Darío Stacchiola, Mónica Calatayud, Frederik Tielens, Juan José Delgado, and Adrian Bonivardi. "Surface Reduction Mechanism of Cerium–Gallium Mixed Oxides with Enhanced Redox Properties." Journal of Physical Chemistry C 117, no. 17 (April 24, 2013): 8822–31. http://dx.doi.org/10.1021/jp400285b.

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Mason, Joseph, Christopher Batchelor-McAuley, and Richard G. Compton. "Surface modification imparts selectivity, facilitating redox catalytic studies: quinone mediated oxygen reduction." Physical Chemistry Chemical Physics 15, no. 21 (2013): 8362. http://dx.doi.org/10.1039/c3cp50607j.

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Дисертації з теми "Surface redox reduction"

Chen, Huai-Chun. "Redox and functional characterization of a surface loop spanning residues 536 to 541 in the flavin mononucleotide-binding domain of flavocytochrome P450BM-3 from Bacillus megaterium." Columbus, Ohio : Ohio State University, 2009. http://rave.ohiolink.edu/etdc/view?acc%5Fnum=osu1236370042.

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Pollack, Gerald D. "Timing and Characterization of the Change in the Redox State of Uranium in Precambrian Surface Environments: A Proxy for the Oxidation State of the Atmosphere." unrestricted, 2008. http://etd.gsu.edu/theses/available/etd-12052008-125923/.

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Thesis (Ph. D.)--Georgia State University, 2008.
Title from file title page. Eirik J. Krogstad, committee chair; Andrey Bekker, committee co-chair; W. Crawford Elliott, Timothy E. LaTour, committee members. Description based on contents viewed Aug. 27, 2009. Includes bibliographical references (p. 207-219).

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Singh, Kulveer. "Structure-function studies of the oxidoreductase bilirubin oxidase from Myrothecium verrucaria using an electrochemical quartz crystal microbalance with dissipation." Thesis, University of Oxford, 2014. http://ora.ox.ac.uk/objects/uuid:0376cc7e-f572-4e0c-96f0-43b0b4b91d99.

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This thesis presents the development and redesign of a commercial electrochemical quartz crystal microbalance with dissipation (E–QCM–D). This was used to study factors affecting the efficiency of the four electron reduction catalysed by the fuel cell enzyme bilirubin oxidase from Myrothecium verrucaria immobilised on thiol modified gold surfaces. Within this thesis, the E–QCM–D was used to show that application of a constant potential to bilirubin oxidase adsorbed to thiol-modified gold surfaces causes activity loss that can be attributed to a change in structural arrangement. Varying the load by potential cycling distorts the enzyme by inducing rapid mass loss and denaturation. Attaching the enzyme covalently reduces the mass loss caused by potential cycling but does not mitigate activity loss. Covalent attachment also changes the orientation of the surface bound enzyme as verified by the position of the catalytic wave (related to the overpotential for catalysis) and reactive labelling followed by mass spectrometry analysis. The E–QCM–D was used to show how electrostatic interactions affect enzyme conformation where high pH causes a reduction in both mass loading at the electrode and a reduction in activity. At pH lower than the enzyme isoelectric point, there is a build up of multilayers in a clustered adsorption. When enzyme adsorbs to hydrophobic surfaces there is a rapid denaturation which completely inactivates the enzyme. Changing the surface chemistry from carboxyl groups to hydroxyl and acetamido groups shows that catalysis is shifted to more negative potentials as a result of an enzyme misorientation. Further to this, increasing the chain length of the thiol modifier indicates that an increased distance between surface and enzyme reduces activity, enzyme loading and results in a conformational rearrangement that permits electron transfer over longer distances.

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Sarkar, Sujoy. "Electrocatalytic Studies on Layer-type Ternary Phosphochalcogenides and on the Formation of Nitride Phases." Thesis, 2014. http://hdl.handle.net/2005/3027.

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Research on new, environment-friendly, clean and efficient energy sources have contributed immensely to the development of new technologies for the generation and storage of electrical energy. Heterogeneous ‘electrocatalysis’ involves catalysis of redox reactions where the electrode material, termed as ‘electrocatalyst’ reduces the overpotential and maximizes the current for the processes occurring at the electrode/electrolyte interface. Efficient catalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are of paramount importance for electrochemical energy generation and storage applications in water splitting, fuel cells and batteries. However, high cost of Pt catalysts that are commonly used for such applications restricts their commercial viability. In addition, there are issues related to poisoning of the surface under certain conditions. One particular case of direct methanol fuel cells involves problems of methanol tolerance as well. Hence, the on-going search in this direction, is to search for alternate catalysts that can match the performance of Pt. There is a quest for the development of stable and durable electrocatalysts/ supports for various electrochemical redox reactions particularly based on energy storage and conversion. The present thesis is structured in exploring the multi-functional aspects of ternary palladium phosphochalcogenides (PdPS and PdPSe) that possess layer-type structure with high crystallinity. They are semiconducting in nature and possess favorable electrochemical, electrical and optical properties. The chalcogenide compounds crystallize in orthorhombic symmetry with an indirect band gap close to 1.5 eV. The current study shows the versatility of ternary phosphochalcogenides in the bulk phase as well as in small sizes. The electrocatalytic activities of the chalcoenides are found to be dramatically improved by increasing the electrical conductivity by way of forming composites with reduced graphene oxide (rGO). The average crystallite size of the PdPS and PdPSe are 30 μm ±10 μm (figure 1). The composites are prepared by simple hydrothermal methods without use of any reducing agent and are characterized using various physico-chemical techniques. Figure 1. FESEM images of (a) PdPSe and (b) PdPS. In the present investigations, PdPS and its reduced graphene oxide composite (rGO-PdPS) are shown to be very efficient hydrogen evolution electrocatalysts (figure 2a). The bulk form of PdPS is found to be very active and the composite of PdPS with reduced graphene oxide improves the hydrogen evolution performance dramatically, even superior to state of the art, MoS2-based catalysts. Figure 2. (a) Linear sweep voltammograms of rGO, bulk PdPS, rGO-PdPS composite and 40 % Pt-C in 0.5 M H2SO4 solution (pH 0.8). Scan rate used is 1 mV s-1. (b) Tafel plots for PdPS, rGO, rGO-PdPS and 40 wt% Pt-C in 0.5 M H2SO4 at 1 mVs-1 scan rate. The Tafel slope and the exchange current density values associated with hydrogen evolution reaction are 46 mV dec-1 and 1.4 x 10-4 A cm-2 respectively (figure 2b). The stability of the PdPS-based catalyst is found to be excellent retaining same current densities even after thousand cycles. Moreover, post-HER characterization reveals the durability of the material even after cycling for a long time. Preliminary spectroelectrochemical investigations are attempted to gain further insight in to the HER. Subsequently, the PdPS and its composite are explored as ORR catalysts in alkaline medium. The composite of PdPS with rGO is formed to enhance the catalytic activity of pure PdPS and the electron transfer kinetics is found to be very favorable. The kinetics of the oxygen reduction reactions are followed by RDE/RRDE measurements. It is experimentally verified that the composite eletrocatalyst is very stable, efficient and methanol tolerant in alkaline medium. The characteristics of the composite catalyst are comparable with widely used standard Pt-C for ORR (figure 3a). Moreover, ternary phophochalcogenide, PdPS, combined with rGO shows good catalytic activity towards OER and it affords a current density of 10 mA cm-2 at an overpotential of η = 570 mV (figure 3b). Figure 3. (a) Comparative voltammograms for rGO, bulk PdPS, rGO-PdPS and 40 % Pt-C in 1M KOH at 1600 rpm. The potential is swept at a rate of 5 mVs-1. (b) Linear sweep voltammograms of oxygen evolution reaction on rGO-PdPS, PdPS and 40 % Pt-C in 1 M KOH electrolyte. Scan rate 5 mV s-1. Apart from its tri-functional electrocatalytic behavior, PdPS and its rGO composite act as an anode material for Li-ion batteries showing high storage capacity of lithium (figure 4). The capacity fading of bulk PdPS is analyzed using XRD and SEM. The introduction of rGO, a well-known conducting matrix, improves the performance. Palladium phosphorous selenide (PdPSe) and its composite with rGO (rGO-PdPSe) are also explored as electrocatalysts for HER, ORR and OER. They show the tri¬functional electrocatalytic behavior as well. Figure 4. Discharge capacity as a function of number of cycles for PdPS, rGO rGO-PdPS electrode at current density of 35 mAg-1 in rechargeable lithium ion battery. The next chapter deals with single or few layer PdPS where layer-type PdPS is exfoliated by several methods such as ultra-sonication and solvent exfoliation. Various microscopic and spectroscopic techniques have been used to characterize the material. These sheets show significantly improved electrocatalytic activity towards ORR and HER with notably low onset potential and low Tafel slopes. The charge storage capacity also increases by an order from its bulk counterpart. The catalyst shows excellent stability for HER and good methanol tolerance behavior towards ORR is also observed. This opens up possibilities for applications of few-layer ternary phosphosulphides in energy conversion and storage. However, one should be cautious since the exfoliation results in a slightly different composition of the material. Different aspects of electrodeposition of gallium nanoparticles on exfoliated graphite surfaces from aqueous acidic solution forms part of the next study. The electrodeposited surface is characterized by various microscopic and spectroscopic techniques. The presence of surface plasmon peak in the visible region has led us to explore the use of Ga on EG for SERS studies. This preliminary work shows that the Raman signal of R6G is enhanced in the presence of Ga deposited on EG surface. The research work presented in the next part of the thesis deals with the preparation, physicochemical, spectroscopic characterization of room temperature molten electrolytes based on amides. Room temperature ternary molten electrolyte involving a combination of acetamide, urea and gallium nitrate salt is prepared and the molten eutectic is characterized. An electrochemical process is developed for depositing gallium nitride from the ternary molten electrolyte on Au electrode. Gallium ion is reduced at low potentials while nitrate ion is reduced to produce atomic nitrogen, forming gallium nitride under certain conditions. Au coated TEM grid is used for patterning gallium nitride (figure 5). The deposited gallium nitride is further annealed at high temperature to increase the crystalinity and improve the stoichiometry of gallium nitride. Figure 5. The FESEM image of patterned gallium nitride deposited on Au coated TEM grid. Elemental mapping of Ga and N from the same region is given. The last chapter explores the prepration and uses of textured GaN tubes synthesized from GaOOH rod-like morphology. The precursor material is prepared by simple hydrothermal technique, maintaining certain value for the pH of the solution. The thermal treatment under ammonia atmosphere leads to highly crystalline, single phase textured tube- like morphology. The as-prepared material is explored as photoanodes in photoelectrochemical water splitting, dye sensitized solar cells and active substrate for SERS. The appendix-I discusses the Na-ion storage capacity by rGO-PdPS composite whereas appendix-II deals with the synthesis of InN and FeN from ternary molten electrolyte. (For figures pl refer the abstract pdf file)

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Книги з теми "Surface redox reduction"

International Symposium on Redox Mechanisms and Interfacial Properties of Molecules of Biological Importance (3rd 1987 Honolulu, Hawaii). Redox chemistry and interfacial behavior of biological molecules. New York: Plenum, 1988.

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(Editor), Glenn Dryhurst, and K. Niki (Editor), eds. Redox Chemistry and Interfacial Behavior of Biological Molecules. Springer, 1989.

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Частини книг з теми "Surface redox reduction"

Kano, Kenji, Tomonori Konse, Bunji Uno, and Tanekazu Kubota. "Electrochemical Study of the Mechanism and Kinetics of Oxygen Reduction Mediated by Anthracycline Antibiotics Adsorbed on Electrode Surface." In Redox Chemistry and Interfacial Behavior of Biological Molecules, 267–80. Boston, MA: Springer US, 1988. http://dx.doi.org/10.1007/978-1-4615-9534-2_19.

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Kodama, Tatsuya, Akira Aoki, Satoshi Miura, and Yoshie Kitayama. "Efficient thermochemical cycle for CO2 reduction with coal using a reactive redox system of ferrite." In Studies in Surface Science and Catalysis, 383–86. Elsevier, 1998. http://dx.doi.org/10.1016/s0167-2991(98)80776-3.

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Salagare, Shridevi, Manjushree S. G., and Prashanth S. Adarakatti. "An electroanalytical overview of metal–organic frameworks (MOFs)." In Electrochemistry, 468–503. The Royal Society of Chemistry, 2023. http://dx.doi.org/10.1039/bk9781839169366-00468.

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The development of sustainable energy and extremely sensitive sensors has become increasingly important as global energy and sensing demand has risen drastically in this century. Electrochemical energy storage devices, electrochemical sensors, and electrocatalysis technologies like the O2 reduction reaction, O2 evolution reaction, rapid depletion of fossil fuels, H2 evolution reaction, CO2 reduction reaction and N2 reduction reaction are all highly wanted. The performance of these devices is highly dependent on the electrode materials, which has sparked a lot of interest in the development of new electrode active substances. Metal–organic frameworks with redox-activity (MOFs) are regarded as viable candidates for active substances for such electrochemical applications due to their remarkable structural designability, large specific surface area, and tunable active sites. This chapter covers the processes of MOFs, design techniques for MOF electrodes, and a detailed summary of current MOF developments in electrochemical sensing, electrochemical energy storage, and electrocatalysts. Finally, the challenges and prospects of MOFs in practical applications are thoroughly discussed, paving the way for the development of MOF-based electrochemical devices.

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Adegoke, Kayode Adesina, Solomon Oluwaseun Akinnawo, Olugbenga Solomon Bello, and Nobanathi Wendy Maxakato. "Metal-organic Frameworks and MOF-based Materials for Electrocatalytic CO2 Reduction." In Advanced Catalysts Based on Metal-organic Frameworks (Part 2), 216–58. BENTHAM SCIENCE PUBLISHERS, 2023. http://dx.doi.org/10.2174/9789815136029123010009.

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Numerous CO2 conversion strategies including thermochemical, photoelectrochemical, electrochemical have been adopted extensively in the last decades. However, the electrochemical CO2 reduction (CO2R) to energy-rich chemicals and fuels remains alternative promising technology owing to its ease of operations with an effective green approach. Compared with other energy conversion technologies, the electrochemical reaction conditions are comparatively mild with the ability to operate the reactions in a room temperature and pressure, thereby bringing better feasibility for alleviating anthropogenic atmospheric CO2 emission that threatens global peace. The reaction processes and directions involved can be controlled freely by tuning reductive potential and temperature. In addition, the process of electrochemical reaction is usually proceeded by reactants to gain or lose electron(s) at the surface of the electrode without the need for redox agents, through which the required electricity is derived from some renewable energy sources (solar, wind, geothermal, etc) which do not generate any additional CO2. This makes electrochemical CO2R a green approach with no generation of contaminants. This chapter, therefore, highlighted different metalorganic frameworks (MOFs) and MOF-based materials for electrocatalytic CO2R to energy-rich chemicals. Various strategies for designing MOFs, challenges, and prospects of MOF materials for better improvement of the CO2R were also discussed.

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Bunduchi, Elena, Gheorghe Duca, and Viorica Gladchi. "New Kinetic Parameters for Natural Water Quality Assessment." In Handbook of Research on Water Sciences and Society, 257–70. IGI Global, 2022. http://dx.doi.org/10.4018/978-1-7998-7356-3.ch011.

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The work describes the processes occurring in the natural waters from a kinetic perspective, highlighting the role of various components of the oxygen cycle and putting into evidence two water quality parameters that evaluate the contents in two intermediate products of oxygen reduction up to water, namely hydrogen peroxide and OH radicals. The flows of oxidative equivalents, hydrogen peroxide, and reducers that interact with it are evaluated by the redox state indicator. The pollution by OH “traps” is evaluated by measuring the inhibition capacity (Σki,OH[Si,OH]) parameter. In this work, the authors present the pollution assessment and water self-purification process supported by hydrogen peroxide and OH radicals during the years 2015-2019. The monitored objects were Nistru River in the Dubasari-Vadul-lui-Voda dam segment; its tributaries, Raut and Ichel, at the mouths of confluence with the river; and the Ghidighici and Danceni lakes, the surface water bodies in the Republic of Moldova.

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Agatova, A. I., N. M. Lapina, N. I. Torgunova, and K. V. Kodryan. "Organic matter and its transformation rates in different sea ecosystems." In THE BARENTS SEA SYSTEM, 212–35. Shirshov Institute of Oceanology Publishing House, 2021. http://dx.doi.org/10.29006/978-5-6045110-0-8/(17).

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The article includes proprietary data and data from literature from the last 30 years about the fluctuations in concentration and the elemental and biochemical make-up of the dissolved and particulate organic matter (DOM and POM, respectively) in the different ecosystems of the Barents Sea. The large variability of these values in both surface and deep waters is shown, depending on the intensity of the hydrological and biological processes.DOM concentrations varied from 59 to 664 μMCorg, while POM varied from 0.25 to 38.08 μMCorg. The reduction of the ice cover affected both the distribution and the qualitative composition of the DOM and the POM. This reduction, as well as the increased flow of Atlantic waters, contributed not only to an increase in the primary production of organic matter, but also to a significant intensification of redox and hydrolytic processes of its transformation, especially in the high-latitude part of the Barents Sea. The DOM of the sea is characterized by high C / P ratios, far exceeding those of Redfeld. At the same time, C / N ratios in the most productive waters are close to those of Redfeld. We highlighted four regions in the sea where concentrations of dissolved carbohydrates increase towards the bottom, which indicates that oil hydrocarbons are supplied here.

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Тези доповідей конференцій з теми "Surface redox reduction"

Kim, Jong Won, Kyu Sung Sim, Hyun Myung Son, and Kwang Deog Jung. "Thermochemical Hydrogen Production Using Ni-Ferrite and CH4." In ASME 2003 International Solar Energy Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/isec2003-44084.

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Hydrogen production by a 2-step water-splitting thermochemical cycle using metal oxides (ferrites) redox pairs and CH4 have been studied in this experiment. Reactions were performed in a two-step redox cycle in which the ferrites were reacted with CH4 at 700°C–800°C to produce CO, H2, and various reduced phases (reduction step); these were then reoxidized with water vapor to generate H2 in water-splitting step (oxidation step) at 600°C–700°C. The reduced forms of Ni-Fe2O3, Ni-FeO and Ni-Fe alloy from XRD, showed respectively different reactivity for H2 formation from H2O. These were oxidized to the ferrite phase to produce H2 in the water-splitting step at 600°C–700°C. In reduction reaction at 800°C, carbon deposition arise on surface of Ni-ferrite due to CH4 decomposition. This reduced phase containing carbon, which reacts with H2O at 600°C, produce H2, CO, and CO2. The amount of H2 evolved using reduced phase containing carbon was much than that of other phase.

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Keene, Daniel J., Jane H. Davidson, and Wojciech Lipiński. "A Model of Transient Heat and Mass Transfer in a Heterogeneous Medium of Cerium Dioxide Undergoing Nonstoichiometric Reduction." In ASME 2012 6th International Conference on Energy Sustainability collocated with the ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/es2012-91380.

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The redox chemistry of nonstoichiometric metal oxides can be used to produce chemical fuels by harnessing concentrated solar energy to split water and/or carbon dioxide. In such a process, it is desirable to use a porous reactive substrate for increased surface area and improved gas transport. The present study develops a macroscopic-scale model of porous ceria undergoing thermal reduction. The model captures the coupled interactions between the heat and mass transfer and the heterogeneous chemistry using a local thermal non-equilibrium (LTNE) formulation of the volume averaged conservation of mass and energy equations in an axisymmetric cylindrical domain. The results of a representative test case simulation demonstrate strong coupling between gas phase mass transfer and the chemical kinetics as well as the pronounced impact of optical thickness on the temperature distribution and thus global solar-to-chemical energy conversion.

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Chen, Cheng-Chuan, Wan-Shao Tsai, and Pei-Kuen Wei. "Aqueous mercuric ions detection using electrochemical surface plasmon resonance in capped gold nanowire arrays." In JSAP-OSA Joint Symposia. Washington, D.C.: Optica Publishing Group, 2017. http://dx.doi.org/10.1364/jsap.2017.5p_a410_10.

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Mercuric ion, inorganic metal ion, found in three oxidation state in nature, including elemental mercury (Hg0), mercurous ion (Hg+), and mercuric ion (Hg2+). These three forms possess hazardous environmental contaminant and are extremely toxic metal materials to damage mammalian organs.[1] This work demonstrates a label-free technique for Hg2+ ions detection using capped gold nanowire arrays based sensors[2] combined with the electrochemical surface plasmon resonance method. The three-electrode electrochemical analysis (Fig. 1) and optical transmission measurement were employed to characterize the potential-current responses and the resonant peak signals were for the investigation of metal ion electrodeposition (Fig. 2). The nanostructured EC-SPR sensors were used to characterize the eletrochemical behaviors of K3Fe(CN)6/K2Fe(CN)6 redox couple and evaluate the wavelength sensitivity (480.3 nm RIU-1) with a FOM of 40.0 RIU-1 and the intensity sensitivity (1819.9 %) in the glycerol-water solutions. Fig. shows the detection limit of 1 pM Hg2+ can be obtained by the chronoamperomet- ric-spectrum analysis. The developed capped gold nanowire arrays based sensors present Hg2+ ion selectivity over the wavelength shifts of the interfering ions including Ca2+, Co2+, Ni2+, Na+, Cu2+, Pb2+, and Mn2+ ions. The developed capped gold nanoslit arrays based sensors present Hg2+ ion selectivity over the wavelength shifts of the interfering ions including Ca2+, Co2+, Ni2+, Na+, Cu2+, Pb2+, and Mn2+ ions. The proposed flexible capped gold nanowire arrays based sensor is applicable to be an EC-SPR label-free platform and enabled a rapid, sensitive and selective sensing method for aqueous Hg2+ detection. The application of biomolecule analysis can be further evaluation in the future. applicable to be an EC-SPR label-free platform and enabled a rapid, sensitive and selective sensing method for aqueous Hg2+ detection. The application of biomolecule analysis can be further evaluation in the future. Fig.1.Schematic representation of electrochemical surface plasmon resonance configuration set-up for mercury ions detection. Fig. 2 Redox current curves during the first cyclic voltammetry scan and the simultaneously measured surface plasmon resonance intensity. Fig. 3. The wavelength shifts and the intensity changes of gold nanowire arrays against Hg2+concentrations between 100|rM and 100nM. The inset shows the reduction reaction currents of amperometric responses at various Hg2+ concentrations.

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Allen, Kyle M., James F. Klausner, Eric N. Coker, Nick AuYeung, and Rishi Mishra. "Synthesis and Analysis of Cobalt Ferrite in YSZ for Use as Reactive Material in Solar Thermochemical Water and Carbon Dioxide Splitting." In ASME 2013 7th International Conference on Energy Sustainability collocated with the ASME 2013 Heat Transfer Summer Conference and the ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/es2013-18254.

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This paper reports the synthesis, characterization and evaluation of different weight loadings of cobalt ferrite (CoFe2O4) in 8 mol% yttria-stabilized zirconia (8YSZ) via the co-precipitation method. Prepared powders were calcined at 1350 °C for 36 hours and 1450 °C for 4 hours in air. These powders were then formed into a porous structure using sacrificial pore formation via oxidation of co-mixed graphite powder. These formed structures obtained were then characterized using thermogravimetric analysis (TGA), X-ray diffraction (XRD), high temperature X-ray diffraction (HT-XRD), scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS). Brunauer-Emmett-Teller (BET) surface area analysis was performed on the most promising of the structures before being subjected to 50 thermal reduction-CO2 oxidation (redox) cycles using TGA. Together, these results indicate that CoFe2O4-8YSZ can provide a lower reduction temperature, maintain syngas production performance from cycle to cycle, and enhance utilization of the reactive material within the inert support in comparison to iron oxide only structures.

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Pozin, A., M. Averbukh, and S. Sukoriansky. "Power Efficiency Optimization of Vanadium Redox Batteries Based on Experimental Analysis of Electrolyte Flow Through Carbon Felt of Electrodes." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36295.

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The Vanadium Redox Flow Battery (VRB) represents a significant opportunity for future Energy Storage Systems (ESS), which will be the crucial element in Renewable Power Plants. Main expectations of VRB relate to its prolonged service life, high-energy efficiency, outstanding dynamic response and flexible controllability during charge/discharge processes. The typical cell of VRB consists of two compartments (positive and negative) divided by a proton exchange membrane (PEM). The carbon electrodes in each compartment provide the electrochemical reduction-oxidation reactions in electrolyte. Carbon felt material as a rule is chosen for electrodes development due to its ability to provide intensive electrochemical reaction owing enlarged external surface and thus a sufficient current (power). The electrolyte on the base of sulfuric acid includes two pairs of vanadium ions with valences: (2+, 3+) in the negative compartment and (4+, 5+) in the positive one. The main volume of electrolyte is stored in two separate tanks and is pumped through both cell’s compartments. There are two main reasons for electrolyte pumping. The first one is the restricted solubility of active vanadium species in sulfuric acid that leads to have an enlarged amount of electrolyte volume, which may be located outside of the cells only. The second reason is the need to decrease concentration polarization effects on the electrode surface. Electric current creates the layer of inactive ions on the electrode surface that increases internal electrical resistance, reduces electromotive force and the battery power. Electrolyte circulation eliminates the effect of polarization but causes hydrodynamic losses. They may be diminished by the optimization of electrolyte flow rate based on correct description of hydrodynamic properties of a carbon felt and on accurate depiction of battery electrical losses. The present research proposes a novel approach to optimization of electrolyte pumping with the purpose to obtain maximum VRB efficiency.

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Chambon, Marc, Ste´phane Abanades, and Gilles Flamant. "Design of a Lab-Scale Rotary Cavity-Type Solar Reactor for Continuous Thermal Reduction of Volatile Oxides Under Reduced Pressure." In ASME 2009 3rd International Conference on Energy Sustainability collocated with the Heat Transfer and InterPACK09 Conferences. ASMEDC, 2009. http://dx.doi.org/10.1115/es2009-90449.

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The investigated two-step MxOy/ MxOy−1 solar thermochemical cycles consist of two redox reactions. Net result is watersplitting with concentrated solar energy as the source of high temperature process heat: 1)Solarreduction:MxOy→MxOy−1+1/2O2(about1700°Catatmosphericpressure,endothermal)2)Hydrolysis:MxOy−1+H2O→MxOy+H2(about400°C,exothermal) The MxOy−1 species produced in reaction (1) is gaseous in the case of the ZnO/Zn cycle. The oxide (ZnO) is injected in a solar thermochemical reactor and undergoes a thermal reduction reaction (oxygen release). Dilution/quenching with a neutral gas at the reactor exit yields nanoparticles of metal by condensation. The particles have a high specific surface area that leads to a high reactivity in the 2nd step. The reduced species (Zn) can then be fed to another reactor to react with water steam. The reaction produces pure H2 and forms the original metal oxide. A high-temperature lab-scale solar reactor prototype was designed, constructed and operated, allowing continuous metal oxide processing under controlled atmosphere. It is based on a cavity-type rotating receiver absorbing solar radiation. The reactant powder is injected continuously inside the cavity and the produced particles (Zn) are recovered in a downstream filter. The solar reduction of ZnO has been achieved, the reaction yields were quantified, and a first concept of solar reactor was qualified.

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Steinkuhler, Claude, Reginald Coomans, and Koen Lenie. "Chemical Decontamination of the Residual Heat Removal System (RHRS) of Flamanville 1." In The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7349.

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The purpose of the decontamination of the RHRS at Flamanville 1 was the reduction of the general dosimetry and the elimination of hot spots. This was done to allow the maintenance on the RHRS equipment. The main challenge of this project was the execution of a complicated operation on the critical path of a shutdown. The redox attack of the oxides at the surface of the circuit in Flamanville, was performed by an EDF qualified process of the EMMAC family. The functions required by the decontamination system were very diverse and therefore an existing decontamination loop, which was previously developed for the decontamination of small system volumes, was re-developed and adapted for bigger circuits. Due to different reasons, an important delay on the planning happened. Therefore, only one cycle EMMAg was performed, totalling 2 hours of decontamination. Despite this, a DRRF (dose rate reduction factor) of 3,7 average was reached. The re-designed equipment and a shortened process were validated during this project. An acceptable DRRF was reached with no delay on the critical path. The capability of maintenance on the RHRS equipment is recovered with a gain of factor 5 on dosimetry.

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PICCOLI, María Belén, Raquel Viviana VICO, and Nancy Fabiana FERREYRA. "ELECTROCHEMICAL CHARACTERIZATION OF GLASSY CARBON ELECTRODES MODIFIED WITH SWCNT FUNCTIONALIZED WITH DIAZONIUM SALT." In SOUTHERN BRAZILIAN JOURNAL OF CHEMISTRY 2021 INTERNATIONAL VIRTUAL CONFERENCE. DR. D. SCIENTIFIC CONSULTING, 2022. http://dx.doi.org/10.48141/sbjchem.21scon.08_abstract_ferreyra.pdf.

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Although carbon nanotubes have unique properties, one of the biggest drawbacks in practice is the difficulty in forming dispersions of individual nanotubes in a given solvent. Covalent functionalization of carbon nanotubes allows the incorporation of chemical groups at the nanotube surface that, according to its polarity, facilitates the dispersibility in different solvents. In this work, singled-wall carbon nanotubes were functionalized by spontaneous grafting with a diazonium salt obtained from the 4-aminobenzoic acid to obtain SWCNT-pB. The nanomaterial obtained was characterized by several methodologies that the covalent incorporation of the functional groups. SWCNT-pB were dispersed in ethanol/water 50% V/V under ultrasonic treatment, and the exfoliation degree was evaluated by UV-Vis spectrophotometry. under optimal conditions, SWCNT-pB dispersion was stable for more than 45 days. Glassy carbon electrodes (GCE) modified with the nanomaterial show significant increases in their capacitive current and a faradaic process due to redox species confined on the surface of SWCNT-pB whose anodic peak currents depend linearly with the scan rate. The modified electrodes also show a catalytic response towards ascorbic acid (AA) and notorious increments in the oxidation and reduction currents of H2O2. The stability of the dispersions and the excellent electrochemical responses obtained make this nanomaterial very interesting for its application in electrochemical detection.

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Steinkuhler, Claude, Koen Lenie, and Reginald Coomans. "Experience in Chemical Decontamination of PWR Systems and Components." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16274.

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Tecnubel has recently performed various chemical decontamination of French and Belgian Pressurized Water Reactors (PWR) systems and components. The purpose of this paper is to present and compare these experiences. The objectives of these operation were the reduction of the general surface contamination together with the elimination of hot spots in Residual Heat Removal Systems (RHRS), Chemical and Volume Control Systems (CVCS) and Reactor Coolant Pumps (RCP). This reduction of contamination leads to the reduction of dosimetry to the maintenance personnel and allows the works on critical equipment. An additional challenge for three of these projects lay in the execution of a complicated operation on the critical path of a reactor refueling shutdown. The chemical decontamination were performed by circulating an adequate fluid in the systems or around the components. Since the contamination was generated at hot conditions during power operation, a redox attack on the surface was necessary. The EDF systems and components were decontaminated using a qualified EDF process of the EMMAC family. The Reactor Coolant Pump from the Belgian PWR was treated with the NITROX process, qualified by Westinghouse. The functions required by the decontamination system were very diverse and therefore an existing decontamination loop, which was previously developed for the decontamination of small circuits, was re-developed and adapted for bigger volumes by DDR Consult and Tecnubel. The results of five decontamination are presented and detailed in terms of efficiency and waste production. These projects were: the chemical decontamination of the RHRS of Flamanville 1 NPP, of the CVCS non regenerative heat exchanger at St Laurent des Eaux NPP, of the RHRS and CVCS of Bugey 2 NPP and of two RCP at the Westinghouse Belgian Service Center.

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Nickson, Ian D., Colin Boxall, Angela Jackson, and Guy O. H. Whillock. "The Development of a Method for the Simultaneous Measurement of Cerium (IV) and Chromium (VI) Species in Nitric Acid Media." In ASME 2009 12th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2009. http://dx.doi.org/10.1115/icem2009-16124.

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The corrosion of stainless steel in nitric acid media is a major concern for the nuclear industry. Several reprocessing schemes such as PUREX (Plutonium Uranium Reduction Extraction) and UREX (Uranium Reduction Extraction) utilise nitric acid media, and an understanding of the behaviour of key chemical species in these process streams is vital if their effect on associated corrosion reactions and their rates is to be accurately assessed and quantified. This will allow for more accurate prediction of the working lifetime of any stainless steel surface in contact with the process stream in question. Two such key species that are found in nuclear process streams are cerium as Ce(IV) and chromium as Cr(VI), both of which may act as corrosion accelerants. The redox chemistry of cerium and chromium in highly active liquor (HAL) will depend on nitrous acid concentration, temperature, acidity, total nitrate and possibly the influence of other dissolved species and hence an analytical technique for the on-line measurement of these quantities would be useful for lifetime prediction and corrosion prevention. As a result of this, a strategy for the simultaneous measurement of both Ce(IV) and Cr(VI) species in the presence of other ions typically found in process streams (such as Iron, Magnesium Neodymium and Aluminium) has been developed. The work presented will discuss the design and implementation of the electrochemical techniques that we have used in the development of this strategy and in the measurement of the species in question.

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