Artykuły w czasopismach: „Co based oxides”

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Neha, Neha, Ram Prasad i Satya Vir Singh. "Simultaneous Catalytic Oxidation of a Lean Mixture of CO-CH4 over Spinel Type Cobalt Based Oxides". Bulletin of Chemical Reaction Engineering & Catalysis 15, nr 2 (12.06.2020): 490–500. http://dx.doi.org/10.9767/bcrec.15.2.6499.490-500.

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A series of nickel-cobalt bimetal oxides in varying molar ratios and its single metal oxides were synthesized by reactive calcination of coprecipitated basic-carbonates. Several characterization techniques, such as: Bruneuer Emmett Teller (BET), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra Red (FTIR), and Hydrogen Temperature Programmed Reduction (H2-TPR), were performed over the oxides. Activities of oxides were evaluated in methane total oxidation in the presence or the absence of CO. The best catalytic performance was observed over NiCo catalyst with a Ni/Co molar ratio of 1:1, and the complete conversion of CO-CH4 mixture was achieved at 390 °C. Moreover, the presence of carbon monoxide improves CH4 total oxidation over nickel-cobalt mixed oxides. Structural analysis reveals that the insertion of nickel into the spinel lattice of cobalt oxide causes the structural disorder, which probably caused the increase of the amount of octahedrally coordinated divalent nickel cations that are responsible for catalytic activity. Stability of the best-performed catalyst has been tested in the two conditions, showing remarkable long-term stability and thermal stability, however, showed deactivation after thermally ageing at 700 °C. Copyright © 2020 BCREC Group. All rights reserved

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Da Silva, Paulo Roberto Nagipe, i Ana Brígida Soares. "Lanthanum based high surface area perovskite-type oxide and application in CO and propane combustion". Eclética Química Journal 34, nr 1 (23.01.2018): 31. http://dx.doi.org/10.26850/1678-4618eqj.v34.1.2009.p31-38.

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The perovskite-type oxides using transition metals present a promising potential as catalysts in total oxidation reaction. The present work investigates the effect of synthesis by oxidant co-precipitation on the catalytic activity of perovskite-type oxides LaBO3 (B= Co, Ni, Mn) in total oxidation of propane and CO. The perovskite-type oxides were characterized by means of X-ray diffraction, nitrogen adsorption (BET method), thermo gravimetric and differential thermal analysis (ATG-DTA) and X-ray photoelectron spectroscopy (XPS). Through a method involving the oxidant co-precipitation it’s possible to obtain catalysts with different BET surface areas, of 33-44 m2/g, according the salts of metal used. The characterization results proved that catalysts have a perovskite phase as well as lanthanum oxide, except LaMnO3, that presents a cationic vacancies and generation for known oxygen excess. The results of catalytic test showed that all oxides have a specific catalytic activity for total oxidation of CO and propane even though the temperatures for total conversion change for each transition metal and substance to be oxidized.

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Cherepanova, Svetlana V., Egor G. Koemets, Evgeny Yu Gerasimov, Irina I. Simentsova i Olga A. Bulavchenko. "Reducibility of Al3+-Modified Co3O4: Influence of Aluminum Distribution". Materials 16, nr 18 (14.09.2023): 6216. http://dx.doi.org/10.3390/ma16186216.

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The reduction of Co-based oxides doped with Al3+ ions has been studied using in situ XRD and TPR techniques. Al3+-modified Co3O4 oxides with the Al mole fraction Al/(Co + Al) = 1/6; 1/7.5 were prepared via coprecipitation, with further calcination at 500 and 850 °C. Using XRD and HAADF-STEM combined with EDS element mapping, the Al3+ cations were dissolved in the Co3O4 lattice; however, the cation distribution differed and depended on the calcination temperature. Heating at 500 °C led to the formation of an inhomogeneous (Co,Al)3O4 solid solution; further treatment at 850 °C provoked the partial decomposition of mixed Co-Al oxides and the formation of particles with an Al-depleted interior and Al-enriched surface. It has been shown that the reduction of cobalt oxide by hydrogen occurs via the following transformations: (Co,Al)3O4 → (Co,Al)O → Co. Depending on the Al distribution, the course of reduction changes. In the case of the inhomogeneous (Co,Al)3O4 solid solution, Al stabilizes intermediate Co(II)-Al(III) oxides during reduction. When Al3+ ions are predominantly on the surface of the Co3O4 particles, the intermediate compound consists of Al-depleted and Al-enriched Co(II)-Al(III) oxides, which are reduced independently. Different distributions of elemental Co and Al in mixed oxides simulate different types of the interaction phase in Co3O4/γ-Al2O3-supported catalysts. These changes in the reduction properties can significantly affect the state of an active component of the Co-based catalysts.

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Zulfugarova, S. M., G. R. Azimova, Z. F. Aleskeroiva, G. M. Guseinli i D. B. Tagiyev. "Catalytic activity of Co, Cu and Mn oxide catalysts synthesized by the sol-gel combustion method in the low-temperature oxidation of carbon oxide". Proceedings of the National Academy of Sciences of Belarus, Chemical Series 59, nr 2 (3.06.2023): 105–14. http://dx.doi.org/10.29235/1561-8331-2023-59-2-105-114.

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The synthesis of catalysts based on cobalt, copper and manganese oxides by sol-gel method with combustion was carried out, and their catalytic activity was studied in the reaction of low-temperature oxidation of carbon monoxide to dioxide. Oxides of cobalt, copper and manganese, as well as their double oxides (Co–Mn, Cu–Mn and Co–Cu) were synthesized. X-ray phase analysis showed the formation of manganites and oxides of corresponding metals in the Co–Mn and Cu–Mn systems. It was revealed that in the Co–Cu system only oxides of separate metals are formed. It was found that cobaltmanganese and copper-manganese oxide systems synthesized by sol-gel combustion method exhibit high catalytic activity in the low-temperature (110–140 0C) conversion of carbon monoxide into dioxide. One-step synthesis of Cu–Mn/Al2O3 catalytic system was also carried out by sol-gel method with burning precursors with binder hydrogel (Al2O3), and its high activity in low-temperature conversion of carbon monoxide was revealed. The catalytic systems were investigated by X-ray diffraction, IR spectral methods, BET, SEM. The results obtained show the possibility of obtaining active multicomponent oxide catalysts in low-temperature oxidation of carbon monoxide by technologically simple sol-gel combustion method.

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Imamura, S., H. Minagawa, M. Ishihara i S. Ishida. "Oxidation of CO on Ag-based composite oxides". Reaction Kinetics & Catalysis Letters 41, nr 1 (marzec 1990): 79–83. http://dx.doi.org/10.1007/bf02075485.

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Xu, Bin, Yi Cheng i Jian Wu. "The Analysis about Harmful Emissions of Micro Combustor Based on Porous Medium". Advanced Materials Research 838-841 (listopad 2013): 2481–87. http://dx.doi.org/10.4028/www.scientific.net/amr.838-841.2481.

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According to the changes of the mixed gas flux ,porosity and burner structure,we measured the contents of CO, HC and Nitrogen Oxides in the harmful emissions of the methane burned in the micro combustor.In the micro scale, because the structure size of the burner is small, the combustion space and time is limited, CO and HC emissions are the products of incomplete combustion, nitrogen oxide are the products in local high temperature and oxygen enriched conditions.

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Fung, Kuan-Zong, Shu-Yi Tsai, Kenneth Fung, Yu-Hsuan Chen, Jen-Hao Yang i Chia-Chin Chang. "Factors Affecting Performance of Single-Crystal Nickel-Rich Layered Oxides Cathode". ECS Meeting Abstracts MA2023-02, nr 2 (22.12.2023): 287. http://dx.doi.org/10.1149/ma2023-022287mtgabs.

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For the past decades, multi-element layered oxide such as Li(Ni,Co,Mn)O2 has been processed by a very popular co-precipitation method. Recently, layered oxides obtained by a single-crystal process has received great attention. The oxides prepared by co-precipitation typically show very uniform and fine particles in nm range <500nm. However, very fine co-precipitated oxide particles with large specific area may suffer from reaction with liquid electrolyte. When the grain size of Ni-rich layered oxides reaches µm range, they tend to show better cycling performance with better structural integrity and less volume change during charge/discharge cycles. Toward the formation of single crystal Ni-rich layered oxides, it may involve decomposition, chemical reactions, diffusion, oxidation, sintering, grain-growth. As a result, factors such as temperature, annealing period and atmospheres may be critical for high-performance cathode. Thus, the objective of this study is (1) to identify what are key factors; (2) the role of key factors; (3) optimization of key factors for better performance. For factor verification and understanding of single crystal process, the resulted electrical, optical, structural, and electrochemical properties of layered oxides will be analyzed and discussed based on defect chemistry consideration. During the different stages of processing, the structural, microstructural and electrical properties of decomposed precursors and resultant layered oxides will be examined using XRD, SEM and DC/AC impedance measurements. CV and charge/discharge tests from assembled coin cells will be used to evaluate electrochemical properties of single-crystal Ni-rich layered oxides.

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Park, Kyoung Ryeol, Jae Eun Jeon, Ghulam Ali, Yong-Ho Ko, Jaewoong Lee, HyukSu Han i Sungwook Mhin. "Oxygen Evolution Reaction of Co-Mn-O Electrocatalyst Prepared by Solution Combustion Synthesis". Catalysts 9, nr 6 (24.06.2019): 564. http://dx.doi.org/10.3390/catal9060564.

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High-performance oxygen evolution reaction (OER) electrocatalysts are needed to produce hydrogen for energy generation through a carbon-free route. In this work, the solution combustion synthesis (SCS) method was employed to synthesize mixed phases of Co- and Mn-based oxides, and the relationships between the crystalline structure and the catalytic properties in the mixed phases were established. The mixed phases of Co- and Mn-based oxides shows promising OER properties, such as acceptable overpotential (450 mV for 10 mA∙cm−2) and Tafel slope (35.8 mV∙dec−1), highlighting the use of the mixed phases of Co- and Mn-based oxides as a new efficient catalysts for water splitting. Electronic structure of the mixed phases of Co- and Mn based oxides is studied in detail to give insight for the origin of high catalytic activities. In addition, excellent long-term stability for OER in alkaline media is achieved for the mixed phase of Co- and Mn based oxides.

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Hyun, Hyejeong, i Jongwoo Lim. "Elucidating degradation mechanisms of Co-free high-Ni layered oxide cathodes for Li-ion batteries via advanced X-ray-based characterization methods". Ceramist 26, nr 1 (31.03.2023): 138–57. http://dx.doi.org/10.31613/ceramist.2023.26.1.10.

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High-Ni layered oxide cathodes without Co are being investigated as potential cathode materials for Li-ion batteries with high energy density. By decreasing the Co content, these cathodes not only boost energy density but also alleviate concerns about the supply instability and fluctuating cost of Co raw materials. However, the elevated Ni content in the layered oxides causes distinct chemo-mechanical degradation mechanisms that inhibit their commercial application. In order to gain insight into the degradation process at various scales, from the atomic to the particle and the electrode levels, and to devise ways to prevent degradation, multi-scale characterization methods are essential. In this review, we critically evaluate the role of Co substitution in high-Ni layered oxides and the impact of Co content on the chemo-mechanical degradation process. Furthermore, the use of advanced X-ray-based characterization methods, which have helped shed light on the degradation mechanisms of high-Ni cathodes, is also discussed.

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Jetpisbayeva, G. D., B. K. Massalimova i A. B. Daulet. "SYNTHESIS OF PEROFSKITE-LIKE Co-CONTAINING CATALYST". SERIES CHEMISTRY AND TECHNOLOGY 2, nr 440 (15.04.2020): 115–19. http://dx.doi.org/10.32014/2020.2518-1491.31.

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There are several approaches to the preparation of catalysts with a developed surface based on oxides with a perovskite structure. Perovskites, due to the possibility of easy variation of chemical composition, make it possible to choose the optimal composition of the catalyst and surface area, and as a result it is possible to influence effectively the selectivity. Perovskite-like LaMeO3 oxides are one of the most promising catalysts for many oxidation processes due to their high activity in oxidative reactions and the stability in aggressive environment. Pekini method (polymer complexes method) and its simplified variant - citrate method are the most widely used for the synthesis of perovskite-like oxides. This article reports about the synthesis of perovskite-like complex oxide LaCoO3 obtained in two ways: hydrothermal, using ethylene glycol, and the citrate method using the template – mesoporous silica KIT-6. The structure of the samples obtained was determined by the XRD method. As a result, it was found that the catalysts have a perovskite structure. Key words: LaCoO3 , perovskite, KIT-6.

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S. I., Vecherskii, Konopel’ko M. A. i Batalov N. N. "Catalytic activity oF LaLi0.1M0.1Fe0.8O3-d (M = Fe, Co, Ni) Oxides for molten carbonate fuel cell. Part 2. Reaction Mechanisms and Catalytic Activity in (Li0.62K0.38)2CO3 Melt". Electrochemical Energetics 14, nr 4 (2014): 197–205. http://dx.doi.org/10.18500/1608-4039-2014-14-4-197-205.

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New mechanisms of oxygen reduction on perovskite related oxides LaLi0:1M0:1Fe0:8O3−d (M = Fe, Co, Ni) and a rock salt type oxide Li0:1Ni0:9O have been proposed. Based on these mechanisms, a comparison of catalytic activity of the oxides in the temperature range 820–1000 K has been done. It has been shown that catalytic activity of LaLi0:Co0:1Fe0:8O3−d oxide exceeds the activity of Li0:1Ni0:9O below 970 K.

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Muldakhmetov, Zainulla M., Nina M. Ivanova, Yakha A. Vissurkhanova i Yelena A. Soboleva. "Preparation and Electrocatalytic Application of Copper- and Cobalt-Carbon Composites Based on Pyrolyzed Polymer". Catalysts 12, nr 8 (5.08.2022): 862. http://dx.doi.org/10.3390/catal12080862.

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Copper- and cobalt-containing carbon composites were prepared by pyrolysis of an aniline-formaldehyde polymer (AFP) doped with the metal oxides, followed by the reduction of metal cations in an electrochemical cell. AFP + metal oxide nanocomposites were synthesized by introducing a metal salt during the polycondensation of aniline with formaldehyde and by alkaline precipitation of metal oxides into the polymer matrix. The heat treatment was carried out at 400, 500 and 700 °C. Microscopic studies revealed the formation of CuO crystallites in the shape of "stars" on the heat-treated carbon material. The resulting composites were saturated with hydrogen in an electrochemical system, which was accompanied by the reduction of copper and cobalt cations, and the appearance of the metals in zero-valence state. The so-prepared Cu + copper oxides/C and Co + Co(OH)2/C composites were used as electrocatalysts in the electrohydrogenation of acetophenone (APh). Compared to the electrochemical reduction of APh on a copper cathode (without catalysts), an increase in the rate of this process (by 2–4 times) in the presence of the composites and an increase in the APh conversion with the selective formation of 1-phenylethanol were established.

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Trusova, Elena A., i Klara V. Kotsareva. "Preparation of Highly-Dispersed Powders of Cobalt, Nickel, Molybdenum and Tungsten Oxides by Modified Sol-Gel Technique". Advances in Science and Technology 87 (październik 2014): 42–47. http://dx.doi.org/10.4028/www.scientific.net/ast.87.42.

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The modified sol-gel technique for the preparation of Со, Ni, Mo and W oxides nanoand submicron powders as well as binary composites based on them was developed. The optimal parameters of synthesis of metal oxide nanopowders with a particle size less than 100 nm were determined. The developed approach allows to obtain the nanoscale metal oxide particles with the given sizes, varying their within range 10-1000 nm. Mesoporous composites containing Mo-, Co-, Ni-oxides, Al2O3 and Ti-silicate were synthesized, characterized and tested in the catalytic alcohol synthesis from CO and H2. It was found that selectivity to C1-C4-alcohols formed over model catalytic systems reaches 50-85% in temperature range 280-360°С.

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Sawaguri, Hiroki, Daichi Yasuhara i Nobuyuki Gokon. "Redox Performance and Optimization of the Chemical Composition of Lanthanum–Strontium–Manganese-Based Perovskite Oxide for Two-Step Thermochemical CO2 Splitting". Processes 11, nr 9 (11.09.2023): 2717. http://dx.doi.org/10.3390/pr11092717.

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The effects of substitution at the A- and B sites on the redox performance of a series of lanthanum–strontium–manganese (LSM)-based perovskite oxides (Z = Ni, Co, and Mg) were studied for application in a two-step thermochemical CO2 splitting cycle to produce liquid fuel from synthesis gas using concentrated solar radiation as the proposed energy source and CO2 recovered from the atmosphere as the prospective chemical source. The redox reactivity, stoichiometry of oxygen/CO production, and optimum chemical composition of Ni-, Co-, and Mg-substituted LSM perovskites were investigated to enhance oxygen/CO productivity. Furthermore, the long-term thermal stabilities and thermochemical repeatabilities of the oxides were evaluated and compared with previous data. The valence changes in the constituent ionic species of the perovskite oxides were studied and evaluated by X-ray photoelectron spectroscopy (XPS) for each step of the thermochemical cycle. From the perspectives of high redox reactivity, stoichiometric oxygen/CO production, and thermally stable repeatability in long-term thermochemical cycling, Ni0.20-, Co0.35-, and Mg0.125-substituted La0.7Sr0.3Mn perovskite oxides are the most promising materials among the LSM perovskite oxides for two-step thermochemical CO2 splitting, showing CO productivities of 387–533 μmol/g and time-averaged CO productivities of 12.9–18.0 μmol/(min·g) compared with those of LSM perovskites reported in the literature.

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Zhang, L., X. B. He, X. H. Qu, Y. Liu, M. L. Qin i H. M. Zhu. "Characteristics of complex oxides in Co based ODS alloys". Powder Metallurgy 56, nr 1 (luty 2013): 24–31. http://dx.doi.org/10.1179/1743290112y.0000000017.

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Hamdani, M., R. N. Singh i P. Chartier. "Co3O4 and Co- Based Spinel Oxides Bifunctional Oxygen Electrodes". International Journal of Electrochemical Science 5, nr 4 (kwiecień 2010): 556–77. http://dx.doi.org/10.1016/s1452-3981(23)15306-5.

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Zhou, Yun Long, Chen Hao Zhao, Zhi Biao Hu, Xue Yan Huang, Kai Yu Liu i Xiao Lin Lang. "Preparation of Co-Ni Mixed Oxide/Graphene Composite and its Electrochemical Performances as Supercapacitor Material". Key Engineering Materials 727 (styczeń 2017): 775–80. http://dx.doi.org/10.4028/www.scientific.net/kem.727.775.

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The Co-Ni mixed oxides/graphene composite has been prepared using the solution based oxidation route. The structures of bare Co-Ni mixed oxides and Co-Ni mixed oxides/graphene composite is clearly studied by X-ray diffraction. The electrochemical properties of Co-Ni mixed oxides/graphene composite are investigated by Cyclic Voltammetry (CV) and galvanostatic charge discharge test. The result shows that, the NiO phase has not been detected in the composite, and the graphene composite delivers a discharge capacity of 353.6 F/g at a current density of 0.32 A g-1.

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Yadav, S., N. Rani i K. Saini. "A review on transition metal oxides based nanocomposites, their synthesis techniques, different morphologies and potential applications". IOP Conference Series: Materials Science and Engineering 1225, nr 1 (1.02.2022): 012004. http://dx.doi.org/10.1088/1757-899x/1225/1/012004.

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Abstract In the field of nanotechnology and nanoscience, transition metal oxides based nanocomposites (TMONCs) are promising for various application uses such as Supercapacitors, Sensors, Bactericidal properties, Photocatalytic Degradation, Solar Cells etc. Modification of transition metal oxide nanoparticles (TMONPs) to TMONCs by doping/mixing of another transition metal and metal oxide, carbon based nanoparticles, conducting polymers etc. to achieve enhanced surface area, increasing surface activities or number of active surface sites, reducing electron-hole recombination, increasing charge transfer processes etc. have been reported in literature. These improved properties are the possible reason for the enhancement in its practical applications efficiencies. This review summarizes recent development on transition metal oxides based nanocomposites for different potential applications. Also synthesis methods of transition metal oxide based nanocomposites have obtained an increasing attractions to achieve cost effectiveness and environment friendly routes of synthesis with high rate of production, high yield of product and also less toxic waste production. Transition metal oxides nanocomposites have been fabricated by various methods such as Microwave assisted synthesis technique, Sol-Gel method, Biosynthesis method, Co-precipitation process, Simple Chemical method etc. Different morphologies of transition metal oxides based nanocomposites have been summarized in this review article. Herein, this paper discuss about several reported synthesis techniques, various characterization techniques used for structural and surface properties identifications, different morphologies and various potential applications of transition metal oxide based nanocomposites.

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Ye, Zhi Guo, Xian Liang Zhou, Hui Min Meng, Xiao Zhen Hua, Ying Hu Dong i Ai Hua Zou. "The Electrochemical Characterization of Electrochemically Synthesized MnO₂-Based Mixed Oxides for Supercapacitor Applications". Advanced Materials Research 287-290 (lipiec 2011): 1290–98. http://dx.doi.org/10.4028/www.scientific.net/amr.287-290.1290.

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Nanostructured elements, including: manganese-molybdenum (Mn-Mo) oxide, manganese-molybdenum-tungsten (Mn-Mo-W) oxide, manganese-molybdenum-iron (Mn-Mo-Fe) oxide, manganese-molybdenum-cobalt (Mn-Mo-Co) oxide, manganese-vanadium-tungsten (Mn-V-W) oxide, manganese-vanadium-iron (Mn-V-Fe) oxide and manganese-iron (Mn-Fe) oxide, have been anodically deposited onto titanium substrates by employing an iridium dioxide interlayer (Ti/IrO2anode). The electrochemical characteristics of the resultant oxide deposits have been investigated by cyclic voltammetry (CV) in an aqueous 0.1 M Na2SO4solution. The voltammetric behaviors of the oxide deposits observed are significantly influenced by the doped elements. Molybdenum doping is found to be advantageous at improving the capacitance characteristics of anodically deposited manganese oxide. Comparatively, iron and vanadium doping are found to be unfavorable. The structure and crystallinity of these deposits have been identified by X-ray diffraction (XRD). The surface morphologies of these oxides were acquired from field emission scanning electron microscopes (FESEM). The high values of electrical parameters for the doped deposits are attributed to the net-like and sponge-like nanostructure, and low crystallinity of the doped manganese oxides. The deposit of Mn-Mo oxides exhibits an excellent capacitive-like behavior, possessing the maximum specific capacitance of 810 F g-1at a CV scan rate of 5 mV s-1in aqueous 0.1 M Na2SO4solution.

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van Limpt, Renee, Marek Lavorenti, Mengmeng Lao, Marcel A. Verheijen, Michail N. Tsampas i Mariadriana Creatore. "Digital Composition Control of Cobalt Nickel Oxides by ALD for the Oxygen Evolution Reaction". ECS Meeting Abstracts MA2023-02, nr 29 (22.12.2023): 1504. http://dx.doi.org/10.1149/ma2023-02291504mtgabs.

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Anion exchange membrane water electrolysis is a potentially low-cost and sustainable technology for renewable-energy driven hydrogen production. Realisation of its full potential relies on the development of cost-effective, earth-abundant OER electrocatalysts alternatives to the state-of-the art noble metal oxides1. Ternary transition metal oxides, such as cobalt nickel oxides, are promising candidates due to their excellent alkali resistance in combination with remarkable catalytic activities. The latter relate to their tuneable oxidation states and variation in coordination of their metal centres. These correlations can be properly investigated when precise control over the layer chemical composition is attained. Atomic layer deposition (ALD) is widely acknowledged to deliver control over film uniformity, thickness and conformality, as well as film chemical composition due to the self-limiting nature of its surface reactions. In this study, an ALD supercycle process based on cobalt cyclopentadienyl (CoCp2) and nickel methylcyclopentadienyl (Ni(MeCp)2) precursors and an oxygen plasma co-reactant has been developed2 to investigate the influence of chemical composition and crystallographic properties of cobalt nickel oxide thin films on their electrocatalytic OER performance. Deposition of ~20 nm binary nickel oxide and cobalt oxide results in the growth of polycrystalline films of the rock-salt and spinel phase, respectively. Ternary cobalt nickel oxide films with various ratios can be deposited uniformly, as indicated by energy dispersive x-ray spectroscopy mapping. The mixed oxides display a transition from the +2 oxidation state-based pure rock-salt phase (<25 at.% Co) to the spinel phase consisting of mixed +2/+3 oxidation states (>75% at.% Co) upon increasing Co at.% as verified by electron diffraction (figure a) and x-ray photoelectron spectroscopy (XPS). XPS furthermore reveals a linear increase in the Ni3+-to-Ni2+ ratio with increasing Co at.%, which indicates that an inverse spinel structure is formed. The formation of a Ni3+-rich inverse spinel cobalt nickel oxide between 55 and 75 at.% Co facilitates the formation of a semi-metallic state (102 S/cm) as opposed to the poorly conductive binary oxides (10-3 S/cm and 10-2 S/cm for NiO and Co3O4, respectively). Cyclic voltammetry (CV) measurements in 1M KOH, reveal chemical composition dependent activation behaviour (figure b). Continuous activation behaviour is observed for rock-salt phase films, whilst increment of the Co at.% results in reduced film activation until virtually no activation of the spinel phase films is observed. The activation of the nickel-rich film is accompanied by irreversible redox changes from the +2 to +3 oxidation state as indicated by the integrated non-catalytic wave. Post CV XPS analysis confirms the transition from Co2+ and Ni2+ oxidation states to Co3+ and Ni3+. The formation of an (oxy)hydroxide state is observed for the rock-salt dominated films, whilst oxidation states characteristic of a spinel- like oxide structure are observed for the cobalt-rich films. No changes in the transition metal ratios are observed after activation. Scanning electron microscopy images furthermore reveal that the transformation of the Ni-rich films is accompanied by surface restructuring. These results indicate that initial composition can significantly influence the electrocatalytic performance of ternary oxides and therefore highlight the importance of techniques such as atomic layer deposition to study their complex behaviour. 1Xu et al., Energy Chem., 4 (2022) 100087 2van Limpt et al., J. Vac. Sci. Technol. A, 41 (2023) 032407 This work has been carried out within the SCALE project (NWA.1237.18.001) funded jointly by the Netherlands Organization for Scientific Research. Authors would like to thank the co-founders of the project ISPT, Syngaschem, VecoPrecision and Vsparticle and international partners Toyota Motor Europe and FORTH institute. Figure: (a) ALD deposited cobalt nickel oxide film show a transition from the +2 oxidation state-based rock-salt phase (NiO) to the spinel structure consisting of mixed +2/+3 oxidation states (Co3O4) upon tuning the chemical composition as identified by electron diffraction. (b) This significantly affects the OER-electrocatalytic performance and activation of the films as represented by the current density at 1.8V vs RHE over 500 CV cycles in 1M KOH. Data labels indicate cobalt concentration as at.% Co/(at.% Co+ at.% Ni). Figure 1

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Barauskienė, Ieva, i Eugenijus Valatka. "Water-Based Electrophoretic Deposition of Ternary Cobalt-Nickel-Iron Oxides on AISI304 Stainless Steel for Oxygen Evolution". Catalysts 12, nr 5 (28.04.2022): 490. http://dx.doi.org/10.3390/catal12050490.

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Coatings consisting of cobalt, nickel and iron (Co-Ni-Fe) oxides were electrophoretically deposited on AISI 304-type stainless steel using aqueous suspensions without any binder. The synthesis of Co-Ni-Fe oxides was carried out by the thermal decomposition of metal nitrates with various molar ratios at 673 K. Structural and morphological analysis confirmed that the deposited coatings were mainly composed of spinel-type oxides with predominantly round-shaped particles. The prepared electrodes were examined for their electrocatalytic performance in oxygen generation under alkaline conditions. Various electrochemical techniques indicated the influence of iron content on the electrochemical activity of Co-Ni-Fe oxides, with the calculated values of the Tafel constant being in the range of 52–59 mV dec−1. Long-term oxygen generation for 24 h at 1.0 V revealed very good mechanical and electrocatalytic stability of the prepared electrodes, since they were able to maintain up to 98% of their initial activity.

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Tang, Rui, Rui He, Sangmo Kim i Chung Wung Bark. "Ferroelectric B-Site Modified Bismuth Lanthanum Titanate Thin Films for High-Efficiency PV Systems". Coatings 12, nr 9 (9.09.2022): 1315. http://dx.doi.org/10.3390/coatings12091315.

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Over the past decades, ferroelectric photovoltaic (FE-PV) systems, which use a homogenous ferroelectric material as a light-absorbing layer, have been studied using ferroelectric oxides. The PV activity of materials can be enhanced by adjusting the bandgap of materials, and it would have a large effect on the ferroelectric complex oxides. This phenomenon in epitaxial thin films of ferroelectric complex oxide, Bi3.25La0.75Ti3O12 (BLT), Fe- and Co-doped films were observed. Compared with undoped BLT, Co-(BLCT) doping and Fe and Co combined (BLFCT) doping resulted in the gradual reduction in the bandgap and efficient visible light absorption. The reduction in the bandgap to 11.4% and 18.1% smaller than the experimentally measured Eg of the bismuth titanate-based film using a simple Fe- and Co-doping method was performed, while maintaining ferroelectricity by analyzing the BLCT and BLFCT films based on polarization loops, and the temperature range of the out-of-plane lattice parameters and the photocurrent density of the BLFCT film was 32.2 times higher than that of the BLT film, which was caused by the decrease in the bandgap. This simple doping technique can be used to tune additional wide-bandgap complex oxides so that they can be used in photovoltaic energy conversion or optoelectronic devices.

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Matsumoto, Y., H. Koinuma, T. Hasegawa, I. Takeuchi, F. Tsui i Young K. Yoo. "Combinatorial Investigation of Spintronic Materials". MRS Bulletin 28, nr 10 (październik 2003): 734–39. http://dx.doi.org/10.1557/mrs2003.215.

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AbstractHigh-throughput synthesis and characterization techniques have been effective in discovering new materials and performing rapid mapping of phase diagrams. The application of the combinatorial strategy to explore doped transition-metal oxides has led to the discovery of a transparent room-temperature ferromagnetic oxide in Co-doped anatase TiO2. The discovery has triggered a wave of studies into other metal oxide systems in pursuit of diluted magnetic semiconductors. In this article, we describe recent combinatorial studies of magnetic transition-metal oxides, germanium-based magnetic semiconductors, and Heusler alloys.

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Bervian, A., Matias Angelis Korb, I. D. Savaris, G. A. Ludwig, L. S. Barreto, G. Gauthier i Célia de Fraga Malfatti. "Phases Obtained from Heat Treatment of Mn-Co-Based Coatings Deposited by Dip Coating". Materials Science Forum 798-799 (czerwiec 2014): 323–27. http://dx.doi.org/10.4028/www.scientific.net/msf.798-799.323.

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Studies have been performed to improve the oxidation resistance of ferritic stainless steels at high temperatures because these materials have been proposed for the manufacture of interconnectors for solid oxide fuel cell (SOFCs) and solid oxide electrolysis cells (SOECs) operating at intermediate temperatures (IT-SOFCs). Among the coatings employed, ceramic spinel-type oxides have been the most frequently applied. In this context, Mn-Co-based coatings were deposited on ferritic stainless steel (AISI 430) in this study using a dip-coating technique. The obtained coatings were characterized with respect to their morphology by SEM, their elementary composition by EDS and their structure by XRD. It was possible to produce continuous and adherent Mn-Co-based coatings on the surface of the metallic substrates.

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Xiao, Yongjian, Yang Yang, Shenglin Kang, Yuchen Li, Xinyuan Hou, Chengjun Ren, Xilin Wang i Xuetong Zhao. "Cold-Sintered ZnO Ceramic Composites Co-Doped with Polytetrafluoroethylene and Oxides". Molecules 29, nr 1 (25.12.2023): 129. http://dx.doi.org/10.3390/molecules29010129.

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Grain boundaries play a significant role in determining the performance of ceramic-based materials. The modulation of interfacial structures provides a promising approach to improve the physicochemical and electrical properties of ceramic materials. In this work, the grain boundary structures of ZnO-based ceramics were manipulated by incorporating polytetrafluoroethylene (PTFE) and metal oxides through the cold sintering process (CSP). It was found that the grain size of ZnO-based ceramics can be effectively reduced from 525.93 nm to 338.08 nm with an addition of PTFE and metal oxides of CoO and Mn2O3. Microstructural results show that most of the PTFE phase and metal oxides were distributed along the grain boundaries, which may lead to the increased grain boundary resistance from 1.59 × 106 ohm of pure ZnO to 6.21 × 1010 ohm of ZnO-based ceramics doped with PTFE and metal oxides, and enhanced Schottky barrier height from 0.32 eV to 0.59 eV. As a result, the breakdown field and nonlinear coefficient of the ZnO-based ceramics were improved to 3555.56 V/mm and 13.55, respectively. Therefore, this work indicates that CSP presents a feasible approach to design functional ceramic composites through the integration of polymer and metal oxides.

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Gonzaga, Ian Lorenzo E., i Candy C. Mercado. "Copper ternary oxides as photocathodes for solar-driven CO₂ reduction". REVIEWS ON ADVANCED MATERIALS SCIENCE 61, nr 1 (1.01.2022): 430–57. http://dx.doi.org/10.1515/rams-2022-0043.

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Abstract The sun’s energy, though free and virtually limitless, is a largely unexploited resource, as its conversion into a storable form presents several technological challenges. A promising way of capturing and storing solar energy is in the form of “solar fuels,” in a process termed artificial photosynthesis. In a photoelectrochemical (PEC) system, the reduction of CO2 to carbon-based fuels is driven on the surface of an illuminated semiconductor electrode. Through the decades, many different classes of semiconducting materials have been studied for this purpose, to varying successes. Because of their cheap and abundant nature, semiconducting transition metal oxides are good candidates to realize this technology in an economic scale and have thus attracted considerable research attention. In this review article, the progress achieved with a specific class of metal oxides, namely, the copper ternary oxides such as copper iron oxide and copper bismuth oxide, for PEC CO2 reduction is examined. Although there have been significant advances in terms of strategies to improve the efficiency and stability of these materials, further studies are warranted to address the many challenges to PEC CO2 reduction and solar fuel production.

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Wang, Aiyong, Bo Lin, Hanlei Zhang, Mark H. Engelhard, Yanglong Guo, Guanzhong Lu, Charles H. F. Peden i Feng Gao. "Ambient temperature NO oxidation over Cr-based amorphous mixed oxide catalysts: effects from the second oxide components". Catalysis Science & Technology 7, nr 11 (2017): 2362–70. http://dx.doi.org/10.1039/c7cy00490g.

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Fu, Guang Yan, Xin Zhao, Qun Liu i Yong Su. "Hot Corrosion of Cobalt-Based Alloy with (Na, K)₂SO₄ Coating at 900 °C". Advanced Materials Research 194-196 (luty 2011): 1305–8. http://dx.doi.org/10.4028/www.scientific.net/amr.194-196.1305.

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The hot corrosion behavior of pure Co, Co-10Cr and Co-10Cr-5Al alloys coated with (4～4.5) mg/cm2 (Na, K)2SO4 deposits has been studied at 900 °C in air by thermogravimetry and SEM/EDX analysis. The results show that hot corrosion rate of Co-10Cr alloy was obviously higher than that of Co-10Cr-5Al alloy and hot corrosion rate of pure Co was between those of the two cobalt-based alloys. Both alloys produced complex corrosion scales, containing an outermost layer of pure cobalt oxide and an inner layer where the oxides of both alloy components were simultaneously present on the Co-10Cr alloy, while a middle layer containing CoO and Cr2O3 and an inner layer of Al2O3 with a few aluminum sulfides appeared on the Co-10Cr-5Al alloy. The results were interpreted by taking into account the effect of active element and hot corrosion mechanism.

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Amiewalan, Florence O., Frankie O. Balogun i Kingsley Ejairu. "Sedimentological and geochemical characterization of DF-2 well, Onshore Western Niger Delta: Implications for provenance, tectonic history and paleo depositional conditions". Global Journal of Pure and Applied Sciences 26, nr 2 (2.11.2020): 141–55. http://dx.doi.org/10.4314/gjpas.v26i2.6.

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The sedimentology and geochemistry of the major oxides and trace elements of DF-2 well, Onshore, Niger Delta, are presented in this study. The study is aimed at describing the sedimentological characteristics as well as using the major oxides and trace elements to investigate the provenance, tectonic history and palaeo-depositional conditions of the well. Selected samples were investigated with fused bead X-Ray Fluorescence (XRF) spectrometry to determine their major oxides and fused bead laser ablation inductively couple plasma mass spectroscopy (LA-ICP-MS) for their trace elements. Sedimentological analysis from the well shows that the lithology ranged from shaly sand, sandy shale, sandstone and shale. The results show the dominance of silicon oxide (SiO2) contents which ranges from 81.1 to 91.4 wt. % (average of 87.1 wt. %). The low average concentration of Cr<150 ppm and Ni <100 ppm, the ratios of Th/Sc, Th/Co, Th/Cr, Cr/Th, La/Sc, as well as the plots of Th/Co versus La/Sc and TiO2 versus Zr, all infer a felsic source rock. The discrimination plots of ratioK2O/Na2O against SiO2 and Log K2O/Na2O against Log SiO2/Al2O3 indicated passive continental margin. Various chemical classifications of the sediments show that the sandstone facies plotted mainly in quartzarenite, sublitharenite and Fe-rich sand domains. The samples were deposited under oxic environment based on the average values of U/Th (0.26 ppm), Ni/Co (2.79 ppm) and Cu/Zn (1.81ppm) and bivariate plot of Ni/Co versus V/Cr. However, the bivariate plot of Ni/Co versus V/ (V+Ni) specifies oxic to anoxic conditions and V/Vi + Ni ratios indicate oxic, suboxic to euxinicpalaeode positional environments for the sediments. Geochemical characterization illustrates mixed marine and terrigenous source input, deposited mainly in semi humid/humid climate. The positive values attained from ratios of Al2O3/(CaO+MgO+Na2O+K2O) infers mineralogical maturity based on stable mobile oxides content in the studied samples. Keywords: Felsic Rock, Quartzarenite, Litharenite, Passive Margin, Mobile Oxide, Mature Sediments.

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Horlait, Denis, Florent Lebreton, Aurélie Gauthé, Marie Caisso, Bénédicte Arab-Chapelet, Sébastien Picart i Thibaud Delahaye. "Americium-based oxides: Dense pellet fabrication from co-converted oxalates". Journal of Nuclear Materials 444, nr 1-3 (styczeń 2014): 181–85. http://dx.doi.org/10.1016/j.jnucmat.2013.09.028.

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Liu, Yuheng, Yuanhua Lin, Lei Jiang, Ce-Wen Nan i Zhijian Shen. "Thermoelectric properties of Bi3+ substituted Co-based misfit-layered oxides". Journal of Electroceramics 21, nr 1-4 (1.09.2007): 748–51. http://dx.doi.org/10.1007/s10832-007-9297-x.

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Ney, V., B. Henne, M. de Souza, W. Jantsch, K. M. Johansen, F. Wilhelm, A. Rogalev i A. Ney. "Valence state, lattice incorporation, and resulting magnetic properties of Ni in Zn/Co-based magnetic oxides". Journal of Applied Physics 133, nr 3 (21.01.2023): 033904. http://dx.doi.org/10.1063/5.0130731.

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Ni incorporation has been studied in a comprehensive range of Zn/Co-based magnetic oxides to elucidate its valence state and lattice incorporation. The resulting structural and magnetic properties of a range of related types of samples are studied in detail. On the one hand, Ni doping is studied in wurtzite ZnO which is either done by in-diffusion of the Ni into bulk ZnO or by reactive magnetron sputtering for Ni-doped thin films of ZnO. The latter is complemented by Ni and Co codoping of ZnO leading to altered magnetic properties which are then dominated by Co. On the other hand, the [Formula: see text] spinel is codoped with varying amounts of Ni. In the wurtzite oxides, Ni is exclusively found on tetrahedral lattice sites in its formal 2+ oxidation state as deep donor. It behaves as an anisotropic paramagnet, and a limited solubility of Ni below 10% is found. Furthermore, the partial compensation of the antiferromagnetically coupled Co magnetic moments is induced by the Ni due to its smaller magnetic moment. In the [Formula: see text] spinel, Ni is found to be incorporated in its formal 3+ oxidation state on octahedral sites and also couples antiferromagnetically to the Co moments. At low Ni concentrations, this leads to a lifting of the partial magnetic compensation of the antiferromagnetic [Formula: see text] spinel and to ferrimagnetism at higher Ni concentrations. Increasing the Ni concentration even further leads to phase separation of cubic NiO resulting in a structurally less defined, exchange-biased composite magnetic oxide.

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Setiawan, Asep Ridwan, i Rochim Suratman. "High Temperature Oxidation Behavior of Co-Based Coating at 800^o C as Alternative Coating Material for SOFC Interconnect". Advanced Materials Research 789 (wrzesień 2013): 498–501. http://dx.doi.org/10.4028/www.scientific.net/amr.789.498.

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Cobalt based oxide are promising as coating material for solid oxide fuel cell interconnect due to their high oxidation resistance and conductivity. In this report, Co-based coating layer was deposited on AISI 430 ferritic stainless steel substrate using thermal spray methods. The high temperature oxidation behavior of Co-based coating was studied in air atmosphere at 800 °C. Optical and SEM observation shows that the total thickness of Co-based layer was about 100-120 μm. The coatings were mainly growth by the melted particles impacting on the substrate that flatten to form splats which later on piled on top of the others. Phase identification by XRD showed that the coating layer contained Co3O4, and NiO oxides. EDS analysis indicated that the coating layer were sufficient to prevents the formation and the growth of Cr2O3scale. The Co-based coating shows relatively a large mass gain during oxidation compared to the uncoated steel, with parabolic rate constant,Kp= 4x10-15gr2.mm-4.ks-1.

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Vershinin, N. N., I. L. Balikhin, E. N. Kurkin, E. N. Kabachkov i Yu M. Shulga. "Synthesis and Properties of a Carbon Monoxide Oxidation Catalyst Based on Titanium Dioxide and Platinum Nanoparticles". Химия высоких энергий 57, nr 4 (1.07.2023): 298–303. http://dx.doi.org/10.31857/s0023119323040149.

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Carbon monoxide oxidation catalysts comprising Pt clusters on titanium dioxide with an oxide particle size of 6 and 20 nm have been synthesized. The catalysts have been studied using TEM, XRD, and XPS techniques, and it has been found that platinum clusters coated with a mixture of platinum oxides are formed on the support surface. The coherent scattering region of the Pt cluster is close to 5–6 nm for the studied oxide supports. The catalytic properties in the CO oxidation reaction at 295 K and low CO concentrations(less than 100 mg/m3) have been examined. The catalyst based on titania with a particle size of 20 nm and a platinum loading of 10 wt % has been found to have the CO oxidation rate 100 times higher than that on platinum black with a specific surface area of 30 m2/g. The catalysts are promising for use in catalytic air purification systems.

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Peng, Jiayu, Livia Giordano, Timothy Davenport i Yang Shao-Horn. "Stability Design Principles of Manganese-Based Oxides in Acid". ECS Meeting Abstracts MA2022-02, nr 42 (9.10.2022): 1604. http://dx.doi.org/10.1149/ma2022-02421604mtgabs.

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The use of non-precious catalysts (e.g., transition metal oxides) in electrochemical energy technologies in acid (e.g., proton exchange membrane fuel cells and electrolyzers) has been significantly hampered by the instability of such catalysts at low pHs. While first-row late transition metal oxides based on Fe, Co, and/or Ni have been reported with comparable or higher catalytic activity for the alkaline oxygen reduction and oxygen evolution reactions than their precious-metal-based counterparts (e.g., Pt and IrO2),[1] these oxide catalysts are not stable in acid.[2] Moreover, Mn-based oxides are more acid-stable than those based on late transition metals[1] and can be potentially stabilized by reaching dissolution-deposition equilibrium at moderately acidic pHs,[3] but they still corrode and deactivate in strong acid and after long operation.[4] To tackle this challenge, extensive efforts over the past decades have been focused on combining active, yet unstable metal oxides with corrosion-resistant oxides.[5-7] Nevertheless, having a higher fraction of corrosion-resistant elements results in more acid-stable, yet less active catalysts, indicating an activity-stability trade-off.[2,5,6] To design transition metal oxide catalysts (such as Mn-based oxides) with an optimal trade-off or bypass this limitation, it is critical to establish their stability descriptors in acid. These descriptors can offer a fundamental understanding of oxide dissolution and provide guiding principles to enhance their intrinsic stability. In this work, we employed a library of Mn-based oxides with diverse structures and Mn oxidation states to identify oxide stability descriptors in acid based on intrinsic electronic structure and energetic parameters. Using time-dependent dissolution experiments and density functional theory calculations, greater amounts and faster kinetics of oxide dissolution in acid were correlated with decreased Mn oxidation states, which are accompanied by lowered Mn-O covalency, weakened Mn-O bonds, and reduced barriers for key reaction steps (such as protonation, vacancy formation, and metal ion solvation). Such design principles were shown broadly with a computational screening across a vast chemical space of ~1,000 Mn-based oxides, where an Mn oxidation state of 4+ was found to give rise to the lowest energetic driving force for the dissolution of Mn-based oxides in acid. Moreover, limiting the percentage of ionic metal substituents in oxides and using more acidic substituents were shown to stabilize Mn-based oxides in acid. These findings can provide novel insights into designing acid-stable Mn-based oxides for renewable energy storage and conversion. References: [1] C. Wei, R. R. Rao, J. Peng, B. Huang, I. E. L. Stephens, M. Risch, Z. J. Xu, Y. Shao-Horn, Adv. Mater. 2019, 31, 1806296. [2] K. K. Rao, Y. Lai, L. Zhou, J. A. Haber, M. Bajdich, J. M. Gregoire, Chem. Mater. 2022, 34, 899. [3] M. Huynh, D. K. Bediako, D. G. Nocera, J. Am. Chem. Soc. 2014, 136, 6002. [4] A. Li, H. Ooka, N. Bonnet, T. Hayashi, Y. Sun, Q. Jiang, C. Li, H. Han, R. Nakamura, Angew. Chem. Int. Ed. 2019, 58, 5054. [5] R. Frydendal, E. A. Paoli, I. Chorkendorff, J. Rossmeisl, I. E. L. Stephens, Adv. Energy Mater. 2015, 5, 1500991. [6] L. Zhou, A. Shinde, J. H. Montoya, A. Singh, S. Gul, J. Yano, Y. Ye, E. J. Crumlin, M. H. Richter, J. K. Cooper, H. S. Stein, J. A. Haber, K. A. Persson, J. M. Gregoire, ACS Catal. 2018, 8, 10938. [7] L. Zhou, H. Li, Y. Lai, M. Richter, K. Kan, J. A. Haber, S. Kelly, Z. Wang, Y. Lu, R. S. Kim, X. Li, J. Yano, J. K. Nørskov, J. M. Gregoire, ACS Energy Lett. 2022, 7, 993. Figure 1

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Mhin, Sungwook. "Recovery of Ni-Co-Mn Oxides from End-of-Life Lithium-Ion Batteries for the Application of a Negative Temperature Coefficient Sensor". Inorganics 12, nr 4 (5.04.2024): 105. http://dx.doi.org/10.3390/inorganics12040105.

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This study demonstrates the current advancements in battery management systems (BMSs), emphasizing the need for precise temperature monitoring within battery packs to enhance safety and performance through efficient thermal management. The increased demand for lithium-ion batteries (LIBs) has driven the development of temperature sensors with improved accuracy and stability. In particular, Ni-Co-Mn-based spinel oxides are commonly used due to their stable negative temperature coefficient (NTC) behavior. However, challenges arise in manufacturing due to the high cost and uncertain supply of critical cathode components (e.g., Co, Ni, and Mn) for LIBs. This research focuses on developing spinel-type (Ni0.6Co0.4Mn2)O4 using recycled Ni-Co-Mn oxides obtained from end-of-life (EOL) LIBs, demonstrating temperature resistance behavior suitable for temperature sensing. The oxides are prepared through hydrometallurgy, oxalate synthesis, and post-heat treatment. Successful integration into spinel-type NTC thermistors suggests broader applications in various industrial fields. A systematic investigation into the synthesis and characterization of recovered Ni-Co-Mn oxides from EOL LIB cathode materials (Li(Ni0.33Co0.33Mn0.33)O2) is presented for NTC thermistor application. Thermogravimetric analysis-derivative thermogravimetry (TGA-DTG) identifies the optimal post-heat treatment temperature. The X-ray diffraction (XRD) patterns confirm a cubic spinel structure of the Ni-Co-Mn oxides, supported by scanning electron microscope (SEM) images showing a uniform microstructure. Also, energy dispersive X-ray spectroscopy (EDS) mapping confirms homogeneous element distribution. Recovered oxide pellets from the sintering process exhibit a single spinel structure, with X-ray photoelectron spectroscopy (XPS) analysis revealing changes in the valence states for Ni and Mn. Resistivity measurements demonstrate semiconductive behavior, which shows a B value (3376.92 K) suitable for NTC thermistor applications. This study contributes valuable insights to black powder recycling from EOL LIBs and its potential in temperature-sensitive electronic devices.

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Belles, Loukas, Constantinos Moularas, Szymon Smykała i Yiannis Deligiannakis. "Flame Spray Pyrolysis Co3O4/CoO as Highly-Efficient Nanocatalyst for Oxygen Reduction Reaction". Nanomaterials 11, nr 4 (5.04.2021): 925. http://dx.doi.org/10.3390/nano11040925.

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The oxygen reduction reaction (ORR) is the rate-limiting reaction in the cathode side of fuel cells. In the quest for alternatives to Pt-electrodes as cathodes in ORR, appropriate transition metal oxide-based electrocatalysts are needed. In the present work, we have synthesized Co3O4 and CoO/Co3O4 nanostructures using flame spray pyrolysis (FSP), as electrocatalysts for ORR in acidic and alkaline media. A detailed study of the effect of (Co-oxide)/Pt ratio on ORR efficiency shows that the present FSP-made Co-oxides are able to perform ORR at very low-Pt loading, 0.4% of total metal content. In acid medium, an electrode with (5.2% Pt + 4.8% Co3O4), achieved the highest ORR performance (Jmax = 8.31 mA/cm2, E1/2 = 0.66 V). In alkaline medium, superior performance and stability have been achieved by an electrode with (0.4%Pt + 9.6% (CoO/Co3O4)) with ORR activity (Jmax = 3.5 mA/cm2, E1/2 = 0.08 V). Using XRD, XPS, Raman and TEM data, we discuss the structural and electronic aspects of the FSP-made Co-oxide catalysts in relation to the ORR performance. Cyclic voltammetry data indicate that the ORR process involves active sites associated with Co3+ cations at the cobalt oxide surface. Technology-wise, the present work demonstrates that the developed FSP-protocols, constitutes a novel scalable process for production of co-oxides appropriate for oxygen reduction reaction electrodes.

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Zhang, Ming Huan, Qing Shao, Lu Yuan, Guang Wen Zhou i Yi Qian Wang. "Mechanism of the Oxidation of Iron". Advanced Materials Research 709 (czerwiec 2013): 106–9. http://dx.doi.org/10.4028/www.scientific.net/amr.709.106.

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A layered structure of different iron oxides was produced by thermal oxidation of iron. The structure and microstructure of different layers were examined using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Selected area electron diffraction (SAED) was used to identify the structures of the different oxide layers. Two different structures of Fe2O3were found to co-exist. Based on our observation, a possible oxidation mechanism for iron was proposed. The results shed light on the oxidation process of metals and provide insight into the synthesis of iron oxides.

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Fabozzi, Antonio, Francesca Cerciello i Osvalda Senneca. "Reduction of Iron Oxides for CO2 Capture Materials". Energies 17, nr 7 (1.04.2024): 1673. http://dx.doi.org/10.3390/en17071673.

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The iron industry is the largest energy-consuming manufacturing sector in the world, emitting 4–5% of the total carbon dioxide (CO2). The development of iron-based systems for CO2 capture and storage could effectively contribute to reducing CO2 emissions. A wide set of different iron oxides, such as hematite (Fe2O3), magnetite (Fe3O4), and wüstite (Fe(1−y)O) could in fact be employed for CO2 capture at room temperature and pressure upon an investigation of their capturing properties. In order to achieve the most functional iron oxide form for CO2 capture, starting from Fe2O3, a reducing agent such as hydrogen (H2) or carbon monoxide (CO) can be employed. In this review, we present the state-of-the-art and recent advances on the different iron oxide materials employed, as well as on their reduction reactions with H2 and CO.

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Pacultová, Bílková, Klegova, Karásková, Fridrichová, Jirátová, Kiška i in. "Co-Mn-Al Mixed Oxides Promoted by K for Direct NO Decomposition: Effect of Preparation Parameters". Catalysts 9, nr 7 (9.07.2019): 593. http://dx.doi.org/10.3390/catal9070593.

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Fundamental research on direct NO decomposition is still needed for the design of a sufficiently active, stable and selective catalyst. Co-based mixed oxides promoted by alkali metals are promising catalysts for direct NO decomposition, but which parameters play the key role in NO decomposition over mixed oxide catalysts? How do applied preparation conditions affect the obtained catalyst’s properties?

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Muşat, Viorica, Nicolae Stănică, Elena Maria Anghel, Irina Atkinson, Daniela Cristina Culiţă, Silviu Poloşan, Lenuţa Crintea (Căpăţână), Alina Cantaragiu Ceoromila, Cristian-Teodor Buruiană i Oana Carp. "Magnetic Core-Shell Iron Oxides-Based Nanophotocatalysts and Nanoadsorbents for Multifunctional Thin Films". Membranes 12, nr 5 (26.04.2022): 466. http://dx.doi.org/10.3390/membranes12050466.

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In recent years, iron oxides-based nanostructured composite materials are of particular interest for the preparation of multifunctional thin films and membranes to be used in sustainable magnetic field adsorption and photocatalysis processes, intelligent coatings, and packing or bio-medical applications. In this paper, superparamagnetic iron oxide (core)-silica (shell) nanoparticles suitable for thin films and membrane functionalization were obtained by co-precipitation and ultrasonic-assisted sol-gel methods. The comparative/combined effect of the magnetic core co-precipitation temperature (80 and 95 °C) and ZnO-doping of the silica shell on the photocatalytic and nano-sorption properties of the resulted composite nanoparticles were investigated by ultraviolet-visible (UV-VIS) spectroscopy monitoring the discoloration of methylene blue (MB) solution under ultraviolet (UV) irradiation and darkness, respectively. The morphology, structure, textural, and magnetic parameters of the investigated powders were evidenced by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, and saturation magnetization (vibrating sample magnetometry, VSM). The intraparticle diffusion model controlled the MB adsorption. The pseudo- and second-order kinetics described the MB photodegradation. When using SiO2-shell functionalized nanoparticles, the adsorption and photodegradation constant rates are three–four times higher than for using starting core iron oxide nanoparticles. The obtained magnetic nanoparticles (MNPs) were tested for films deposition.

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Muşat, Viorica, Nicolae Stănică, Elena Maria Anghel, Irina Atkinson, Daniela Cristina Culiţă, Silviu Poloşan, Lenuţa Crintea (Căpăţână), Alina Cantaragiu Ceoromila, Cristian-Teodor Buruiană i Oana Carp. "Magnetic Core-Shell Iron Oxides-Based Nanophotocatalysts and Nanoadsorbents for Multifunctional Thin Films". Membranes 12, nr 5 (26.04.2022): 466. http://dx.doi.org/10.3390/membranes12050466.

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In recent years, iron oxides-based nanostructured composite materials are of particular interest for the preparation of multifunctional thin films and membranes to be used in sustainable magnetic field adsorption and photocatalysis processes, intelligent coatings, and packing or bio-medical applications. In this paper, superparamagnetic iron oxide (core)-silica (shell) nanoparticles suitable for thin films and membrane functionalization were obtained by co-precipitation and ultrasonic-assisted sol-gel methods. The comparative/combined effect of the magnetic core co-precipitation temperature (80 and 95 °C) and ZnO-doping of the silica shell on the photocatalytic and nano-sorption properties of the resulted composite nanoparticles were investigated by ultraviolet-visible (UV-VIS) spectroscopy monitoring the discoloration of methylene blue (MB) solution under ultraviolet (UV) irradiation and darkness, respectively. The morphology, structure, textural, and magnetic parameters of the investigated powders were evidenced by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, and saturation magnetization (vibrating sample magnetometry, VSM). The intraparticle diffusion model controlled the MB adsorption. The pseudo- and second-order kinetics described the MB photodegradation. When using SiO2-shell functionalized nanoparticles, the adsorption and photodegradation constant rates are three–four times higher than for using starting core iron oxide nanoparticles. The obtained magnetic nanoparticles (MNPs) were tested for films deposition.

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Muşat, Viorica, Nicolae Stănică, Elena Maria Anghel, Irina Atkinson, Daniela Cristina Culiţă, Silviu Poloşan, Lenuţa Crintea (Căpăţână), Alina Cantaragiu Ceoromila, Cristian-Teodor Buruiană i Oana Carp. "Magnetic Core-Shell Iron Oxides-Based Nanophotocatalysts and Nanoadsorbents for Multifunctional Thin Films". Membranes 12, nr 5 (26.04.2022): 466. http://dx.doi.org/10.3390/membranes12050466.

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In recent years, iron oxides-based nanostructured composite materials are of particular interest for the preparation of multifunctional thin films and membranes to be used in sustainable magnetic field adsorption and photocatalysis processes, intelligent coatings, and packing or bio-medical applications. In this paper, superparamagnetic iron oxide (core)-silica (shell) nanoparticles suitable for thin films and membrane functionalization were obtained by co-precipitation and ultrasonic-assisted sol-gel methods. The comparative/combined effect of the magnetic core co-precipitation temperature (80 and 95 °C) and ZnO-doping of the silica shell on the photocatalytic and nano-sorption properties of the resulted composite nanoparticles were investigated by ultraviolet-visible (UV-VIS) spectroscopy monitoring the discoloration of methylene blue (MB) solution under ultraviolet (UV) irradiation and darkness, respectively. The morphology, structure, textural, and magnetic parameters of the investigated powders were evidenced by scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, and saturation magnetization (vibrating sample magnetometry, VSM). The intraparticle diffusion model controlled the MB adsorption. The pseudo- and second-order kinetics described the MB photodegradation. When using SiO2-shell functionalized nanoparticles, the adsorption and photodegradation constant rates are three–four times higher than for using starting core iron oxide nanoparticles. The obtained magnetic nanoparticles (MNPs) were tested for films deposition.

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Sui, Ruohong, Sarah K. Carefoot, Christopher B. Lavery, Connor E. Deering, Kevin L. Lesage, Nancy Chou, Chelsea J. Rose i Robert A. Marriott. "Organosulfur adsorbents by self-assembly of titania based ternary metal oxide nanofibers". Journal of Materials Chemistry A 5, nr 20 (2017): 9561–71. http://dx.doi.org/10.1039/c7ta01856h.

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Stepanova, Liudmila N., Roman M. Mironenko, Mikhail V. Trenikhin, Aleksandra N. Serkova, Aleksei N. Salanov i Aleksandr V. Lavrenov. "CoCuMgAl-Mixed-Oxide-Based Catalysts with Fine-Tunable Composition for the Hydrogenation of Furan Compounds". Journal of Composites Science 8, nr 2 (2.02.2024): 57. http://dx.doi.org/10.3390/jcs8020057.

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Catalysts based on CoCuMgAl mixed oxides were synthesized and studied in the hydrogenations of furfural and 5-hydroxymethylfurfural under different conditions. The changes in the structural properties of the catalysts at different stages of their preparation were studied using a set of physical methods (XRD, SEM, and TEM). It was shown that the fine regulation of the chemical compositions of the mixed oxides (i.e., changes in the Co/Cu ratio) made it possible to vary the structure, morphology, and catalytic properties of the samples. The phase composition of catalysts with Co/Cu = 1 did not change during the catalytic reaction, although the initial catalysts had a less-homogeneous morphology. 5-hydroxymethylfurfural conversion was higher for the samples with Co/Cu = 1. Furfural conversion increased when raising the Co/Cu ratio. The selectivity toward furfuryl alcohol for the catalyst with Co/Cu = 2 under mild conditions of furfural hydrogenation was more than 99%. The results obtained are important for the development of the scientific foundations of the preparation of hydrogenation catalysts with a fine-tunable composition in order to obtain the desired hydrogenation products.

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Ding, Yiwen, Keju Ren, Chen Chen, Li Huan, Rongli Gao, Xiaoling Deng, Gang Chen i in. "High-entropy perovskite ceramics: Advances in structure and properties". Processing and Application of Ceramics 18, nr 1 (2024): 1–11. http://dx.doi.org/10.2298/pac2401001d.

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High-entropy ceramic materials usually refer to the multi-principal solid solution formed by 5 or more ceramic components. Due to its novel ?high-entropy effect? and excellent performance, it has become one of the research hotspots in the field of ceramics in recent years. As the research system of high-entropy ceramics has gradually expanded from the initial rock salt oxides (Mg-Ni-Co-Cu-Zn)O to fluorite oxides, perovskite oxides, spinel oxides, borides, carbides and silicates, its special mechanical, electrical, magnetic and energy storage properties have been continuously discovered. Based on the basic principle of high-entropy materials, this paper mainly introduces the prominent perovskite-type oxide high-entropy ceramics in recent years from the perspective of ceramic structure and properties, and predicts the development trend of high-entropy perovskite-type ceramics in the next few years.

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Razzaq, Rauf, Chunshan Li, Nadeem Amin, Suojiang Zhang i Kenzi Suzuki. "Co-methanation of Carbon Oxides over Nickel-Based CexZr1–xO2 Catalysts". Energy & Fuels 27, nr 11 (29.10.2013): 6955–61. http://dx.doi.org/10.1021/ef401049v.

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Kierzkowska-Pawlak, Hanna, Małgorzata Ryba, Maciej Fronczak, Ryszard Kapica, Jan Sielski, Maciej Sitarz, Patryk Zając, Klaudia Łyszczarz i Jacek Tyczkowski. "Enhancing CO2 Conversion to CO over Plasma-Deposited Composites Based on Mixed Co and Fe Oxides". Catalysts 11, nr 8 (22.07.2021): 883. http://dx.doi.org/10.3390/catal11080883.

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The hydrogenation of CO2 to produce CO and H2O, known as reverse-water-gas shift reaction (RWGS) is considered to be an important CO2 valorization pathway. This work is aimed at proposing the thin-film catalysts based on iron and cobalt oxides for this purpose. A series of Fe–Co nanocomposites were prepared by the plasma-enhanced chemical vapor deposition (PECVD) from organic cobalt and iron precursors on a wire-mesh support. The catalysts were characterized by SEM/EDX, XPS, XRD, and Raman spectroscopy and studied for hydrogenation of CO2 in a tubular reactor operating in the temperature range of 250–400 °C and atmospheric pressure. The Co-based catalyst, containing crystalline CoO phase, exhibited high activity toward CH4, while the Fe-based catalyst, containing crystalline Fe2O3/Fe3O4 phases, was less active and converted CO2 mainly into CO. Regarding the Fe–Co nanocomposites (incl. Fe2O3/Fe3O4 and CoO), even a small fraction of iron dramatically inhibited the production of methane. With increasing the atomic fraction of iron in the Fe–Co systems, the efficiency of the RWGS reaction at 400 °C increased up to 95% selectivity to CO and 30% conversion of CO2, which significantly exceeded the conversion for pure iron–based films (approx. 9%). The superior performance of the Fe–Co nanocomposites compared to “pure” Co and Fe–based films was proposed to be explained by assuming changes in the electronic structure of the catalyst resulting from the formation of p–n junctions between nanoparticles of cobalt and iron oxides.

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Molochas, Costas, i Panagiotis Tsiakaras. "Carbon Monoxide Tolerant Pt-Based Electrocatalysts for H2-PEMFC Applications: Current Progress and Challenges". Catalysts 11, nr 9 (18.09.2021): 1127. http://dx.doi.org/10.3390/catal11091127.

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The activity degradation of hydrogen-fed proton exchange membrane fuel cells (H2-PEMFCs) in the presence of even trace amounts of carbon monoxide (CO) in the H2 fuel is among the major drawbacks currently hindering their commercialization. Although significant progress has been made, the development of a practical anode electrocatalyst with both high CO tolerance and stability has still not occurred. Currently, efforts are being devoted to Pt-based electrocatalysts, including (i) alloys developed via novel synthesis methods, (ii) Pt combinations with metal oxides, (iii) core–shell structures, and (iv) surface-modified Pt/C catalysts. Additionally, the prospect of substituting the conventional carbon black support with advanced carbonaceous materials or metal oxides and carbides has been widely explored. In the present review, we provide a brief introduction to the fundamental aspects of CO tolerance, followed by a comprehensive presentation and thorough discussion of the recent strategies applied to enhance the CO tolerance and stability of anode electrocatalysts. The aim is to determine the progress made so far, highlight the most promising state-of-the-art CO-tolerant electrocatalysts, and identify the contributions of the novel strategies and the future challenges.

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Ocsachoque, Marco Antonio, María Silvia Leguizamón-Aparicio, Mónica Laura Casella i Ileana Daniela Lick. "Promoting Effect of Palladium on ZnAl2O4-Supported Catalysts Based on Cobalt or Copper Oxide on the Activity for the Total Propene Oxidation". Materials 14, nr 17 (25.08.2021): 4814. http://dx.doi.org/10.3390/ma14174814.

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Palladium-modified Co-ZnAland Cu-ZnAl materials were used and found active for the catalytic oxidation of propene and propane. According to the results obtained by XRD, TPR and XPS, the zinc aluminate-supported phases are oxide phases, Co3O4, CuO and PdOx for Co-ZnAl, Cu-ZnAl and Pd-ZnAl catalysts, respectively. These reducible oxide species present good catalytic activity for the oxidation reactions. The addition of palladium to Co-ZnAl or Cu-ZnAl samples promoted the reducibility of the system and, consequently, produced a synergic effect which enhanced the activity for the propene oxidation. The PdCo-ZnAl sample was the most active and exhibited highly dispersed PdOx particles and surface structural defects. In addition, it exhibited good catalytic stability. The H2 pre-treated PdCu-ZnAl, PdCo-ZnAl and Pd-ZnAl samples showed higher activity than the original oxide catalysts, evidencing the important role of the oxidation state of the species, mainly of the palladium species, on the catalytic activity for the propene combustion. The synergic effect between metal transition oxides and PdOx could not be observed for the propane oxidation.

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