Artigos de revistas: "Anodic electrocatalysts"

1

Pham Hong, Hanh, Linh Do Chi, Phong Nguyen Ngoc e Lam Nguyen Duc. "Synthesis and characterization of NiCoOx mixed nanocatalysts for anion exchanger membrane water electrolysis (AEMWE)". Vietnam Journal of Catalysis and Adsorption 9, n.º 2 (31 de julho de 2020): 49–53. http://dx.doi.org/10.51316/jca.2020.028.

Texto completo da fonte

Resumo:

Anion exchange membrane water electrolysis (AEMWE) is a well developed technology for the conversion of water into hydrogen and oxygen. AEMWE is still a developing technology. One of the major advantages of AEM water electrolysis is the replacement ofconventional noble metal electrocatalysts with low cost transition metal catalysts. In this study, we report characterization of NiCoOxmixed metallic oxides synthesized by the hydrolysis method as anodic electrocatalysts for AEMWE. The mechanisms of the thermal decomposition process of precursors to form mixed metallic oxide powders were studied by means of thermal gravity analysis (TGA), X-ray diffraction (XRD) while transmission electron microscopy (TEM) were used to evaluate the crystallographic structure, morphology and size of catalyst particles. The surface reactivity and stability of these oxides was investigated by cyclic voltammetry (CV) electrochemical method in solution of 1 M KOH. Based on the given results, the good anodic electrocatalyst was found.

Estilos ABNT, Harvard, Vancouver, APA, etc.

2

Yun, Young Hwa, Changsoo Lee e Bonjae Koo. "Improvement of Mass Activity of IrO_x Electrocatalyst in Acidic Oxygen Evolution Reaction Using Bi₃TaO₇ Support". ECS Meeting Abstracts MA2024-02, n.º 42 (22 de novembro de 2024): 2786. https://doi.org/10.1149/ma2024-02422786mtgabs.

Texto completo da fonte

Resumo:

Developing highly conductive and durable support materials for Ir-based electrocatalysts in acidic oxygen evolution reactions (OER) is one of the challenges to overcoming corrosion conduction during the anodic process. In this study, we develop an oxide-type support material(Bi3TaO7) for IrOx electrocatalyst in acidic OER to minimize the amount of iridium loading level. Through a combination of various physical and chemical analyses(XRD, TEM, XRF, EIS, XPS, XAS, etc.), it is demonstrated that the IrOx/Bi3TaO7 electrocatalyst showed remarkable OER performances and enhanced mass activity compared to unsupported IrOx electrocatalysts. Bi on the surface of Bi3TaO7 suppresses the change in oxidation state of Ir element, maintains activity of IrOx electrocatalyst during electrochemical reaction and induces chemical and physical stability of the IrOx/Bi3TaO7 electrocatalyst. These findings can provide further insight into a new category of anode support materials for proton exchange membrane water electrolyzers.

Estilos ABNT, Harvard, Vancouver, APA, etc.

3

Balčiūnaitė, Aldona, Noha A. Elessawy, Biljana Šljukić, Arafat Toghan, Sami A. Al-Hussain, Marwa H. Gouda, M. Elsayed Youssef e Diogo M. F. Santos. "Effective Fuel Cell Electrocatalyst with Ultralow Pd Loading on Ni-N-Doped Graphene from Upcycled Water Bottle Waste". Sustainability 16, n.º 17 (29 de agosto de 2024): 7469. http://dx.doi.org/10.3390/su16177469.

Texto completo da fonte

Resumo:

Environmental pollution due to the excessive consumption of fossil fuels for energy production is a critical global issue. Fuel cells convert chemical energy directly into electricity in a clean and silent electrochemical process, but face challenges related to hydrogen storage, handling, and transportation. The direct borohydride fuel cell (DBFC), utilizing sodium borohydride as a liquid fuel, is a promising alternative to overcome such issues but requires the design of cost-effective nanostructured electrocatalysts. In this study, we synthesized nitrogen-doped graphene anchoring Ni nanoparticles (Ni@NG) by thermal degradation of polyethylene terephthalate bottle waste with urea and metallic Ni, and evaluated it as a sustainable carbon support. Electrocatalysts were prepared by incorporating ultralow amounts (0.09 to 0.27 wt.%) of Pd into the Ni@NG support. The resulting PdNi@NG electrocatalysts were characterized using ICP-OES, XPS, TEM, N2-sorption analysis, XRD, and Raman and FTIR spectroscopy. Voltammetry assessed the materials’ electrocatalytic activity for oxygen reduction and borohydride oxidation reactions in alkaline media, corresponding to the anodic and cathodic reactions in DBFCs. The electrocatalyst with 0.27 wt.% Pd loading (PdNi_15@NG) exhibited the best performance for both reactions. Consequently, it was employed as an anodic and cathodic material in a lab-scale DBFC, achieving a specific power of 3.46 kW gPd−1.

Estilos ABNT, Harvard, Vancouver, APA, etc.

4

Heath, Megan Muriel, Elise Fosdal Closs, Svein Sunde, Anita Hamar Reksten, Tor Olav Sunde, Magdalena Müller, Hågen Røe, Abhishek Rajbhandari e Frode Seland. "The Potential of Ruthenate Pyrochlores As Anodic Electroctalysts for PEM Water Electrolysisoral Presentation". ECS Meeting Abstracts MA2024-02, n.º 42 (22 de novembro de 2024): 2847. https://doi.org/10.1149/ma2024-02422847mtgabs.

Texto completo da fonte

Resumo:

Green hydrogen is becoming a hot commodity in the light of escalating oil and gas prices and their uncertain future availability. Among various electrolysis technologies, PEM water electrolysis (WE) is favorable for its portability, modularity, and the ability to integrate with intermittent, renewable energy sources. However, the upscaling of PEMWE is not feasible yet due to the need for rare and expensive metals as electrocatalysts. Specifically, iridium oxide is used as state-of-the art anodic electrocatalyst. Ruthenium oxide also has an excellent activity towards the anodic oxygen evolution reaction (OER), but is highly unstable. To address this limitation, this study investigates ruthenate pyrochlores as alternative anodic electrocatalysts. The pyrochlore structure may stabilize ruthenium. The pyrochlores in this study have been synthesized using a traditional citrate sol-gel method,1 as well as a novel combustion synthesis route. Physical characterization of the electrocatalysts has been conducted using x-ray diffraction (XRD), scanning (transmission) electron spectroscopy (S(T)EM) and Raman spectroscopy. Additionally, ex-situ electrochemical characterization has been performed in a three-electrode setup. Linear-sweep voltammetry results of Y2Ru2O7 synthesised via the citrate sol-gel route indicate an overpotential of 300 mV at a current density of 10 mA cm-2. This result agrees well with what has previously been reported for this electrocatalyst.2 Y2Ru2O7 synthesised via the novel combustion route performs better than the aforementioned due to increased surface area. Various A-site dopants have also been introduced into the pyrochlore structure to generate oxygen vacancies, modify the electronic structure and increase the stability. These materials have also been tested in a full-cell setup to gauge their performance for practical applications compared to state-of-the-art IrO2 and RuO2. References (1) Kim, J.; Shih, P.-C.; Tsao, K.-C.; Pan, Y.-T.; Yin, X.; Sun, C.-J.; Yang, H. High-Performance Pyrochlore-Type Yttrium Ruthenate Electrocatalyst for Oxygen Evolution Reaction in Acidic Media. J. Am. Chem. Soc. 2017, 139 (34), 12076–12083. (2) Feng, Q.; Zou, J.; Wang, Y.; Zhao, Z.; Williams, M. C.; Li, H.; Wang, H. Influence of Surface Oxygen Vacancies and Ruthenium Valence State on the Catalysis of Pyrochlore Oxides. ACS Appl. Mater. Interfaces 2020, 12 (4), 4520–4530.

Estilos ABNT, Harvard, Vancouver, APA, etc.

5

Tian, Na, Bang-An Lu, Xiao-Dong Yang, Rui Huang, Yan-Xia Jiang, Zhi-You Zhou e Shi-Gang Sun. "Rational Design and Synthesis of Low-Temperature Fuel Cell Electrocatalysts". Electrochemical Energy Reviews 1, n.º 1 (março de 2018): 54–83. http://dx.doi.org/10.1007/s41918-018-0004-1.

Texto completo da fonte

Resumo:

Abstract Recent progresses in proton exchange membrane fuel cell electrocatalysts are reviewed in this article in terms of cathodic and anodic reactions with a focus on rational design. These designs are based around gaining active sites using model surface studies and include high-index faceted Pt and Pt-alloy nanocrystals for anodic electrooxidation reactions as well as Pt-based alloy/core–shell structures and carbon-based non-precious metal catalysts for cathodic oxygen reduction reactions (ORR). High-index nanocrystals, alloy nanoparticles, and support effects are highlighted for anodic catalysts, and current developments in ORR electrocatalysts with novel structures and different compositions are emphasized for cathodic catalysts. Active site structures, catalytic performances, and stability in fuel cells are also reviewed for carbon-based non-precious metal catalysts. In addition, further developmental perspectives and the current status of advanced fuel cell electrocatalysts are provided. Graphical Abstract

Estilos ABNT, Harvard, Vancouver, APA, etc.

6

Belhaj, Ines, Alexander Becker, Filipe M. B. Gusmão, Biljana Šljukić, Miguel Chaves, Salete S. Balula, Luís Cunha Silva e Diogo M. F. Santos. "Au-Based MOFs as Anodic Electrocatalysts for Direct Borohydride Fuel Cells". ECS Meeting Abstracts MA2023-02, n.º 41 (22 de dezembro de 2023): 2053. http://dx.doi.org/10.1149/ma2023-02412053mtgabs.

Texto completo da fonte

Resumo:

Researchers are exploring direct liquid fuel cells (DLFCs) as alternatives to proton-exchange membrane fuel cells because of their higher energy density and ease of storing and transporting the fuel. Direct borohydride fuel cells (DBFCs) are of particular interest as they offer a sustainable energy source with their high-power density output and the use of a highly alkaline NaBH4 medium [1]. Ensuring efficient and cost-effective catalysts for DBFCs is crucial for their commercial viability. Metal-organic frameworks (MOFs) have demonstrated significant potential as anodic electrocatalysts for BOR in DBFCs [2]. However, research should explore various modifications to MOFs, such as the incorporation of alternative metal ions or functional groups, to improve their catalytic efficiency and reduce cost. This study evaluated the performance of newly developed MOF-based electrocatalysts for DBFCs. Specifically, six MOF-based materials were synthesized and analyzed for their ability to facilitate borohydride oxidation (BOR) using cyclic voltammetry and chronoamperometry in alkaline media. MIL-101_Au@NH2 and MOF-808_Au@NH2 were found to be highly effective for BOR. The kinetic parameters for BOR with MOF-based electrocatalysts, including activation energy, reaction order, exchanged electrons, and anodic charge transfer coefficient, were determined. The activation energy for BOR was found to be 13.6 kJ mol−1 and 15.3 kJ mol−1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. The number of transferred electrons, n, was found to be 7.0 and 3.1 for MIL-101_Au@NH2 and MOF-808_Au@NH2, respectively. This study demonstrates that MOF-based electrocatalysts can enhance DBFCs' performance, while offering insight into the potential usage of MOFs in other fuel cell technologies. [1] B. Šljukić, D.M.F. Santos, "Direct borohydride fuel cells", in: "Direct Liquid Fuel Cells: Fundamentals, Advances, and Future", 1st ed., R.G. Akay, A.B. Yurtcan (eds.), Academic Press, USA, 203-232 (2021) [2] G. Backovic, B. Šljukić, G.S. Kanberoglu, M. Yurderi, A. Bulut, M. Zahmakiran, D.M.F. Santos, Ruthenium (0) nanoparticles stabilized by the metal-organic framework as an efficient electrocatalyst for borohydride oxidation reaction, International Journal of Hydrogen Energy, 45, 27056-27066 (2020).

Estilos ABNT, Harvard, Vancouver, APA, etc.

7

Protsenko, V. S., D. A. Shaiderov, O. D. Sukhatskyi, T. E. Butyrina, S. A. Korniy e F. I. Danilov. "DES-assisted electrodeposition and characterization of an electrocatalyst for enhanced urea oxidation in green hydrogen production". Voprosy Khimii i Khimicheskoi Tekhnologii, n.º 1 (fevereiro de 2025): 65–70. https://doi.org/10.32434/0321-4095-2025-158-1-65-70.

Texto completo da fonte

Resumo:

An important task of modern materials science is the development of highly efficient electrocatalysts for green hydrogen production. Specifically, this involves the urea oxidation reaction (UOR), which is an energetically advantageous and attractive alternative to the anodic oxygen evolution reaction, coupled with hydrogen evolution at the cathode. In this work, we present for the first time the use of systems based on a new generation of environmentally friendly room-temperature ionic liquids – deep eutectic solvents (DESs) – for the electrodeposition of electrocatalysts for UOR. The electrochemical performance of electrodeposited nanocomposite Ni–CeO2 electrocatalysts was evaluated in alkaline solution, showing an appreciable reduction in the anodic potential of UOR compared to oxygen evolution, reaching up to approximately 0.2 V at a current density of 0.1 mA cm–2. The obtained results are significant for the development of electrochemical synthesis methods for electrocatalysts used in green renewable energy.

Estilos ABNT, Harvard, Vancouver, APA, etc.

8

Gunji, Takao, e Futoshi Matsumoto. "Electrocatalytic Activities towards the Electrochemical Oxidation of Formic Acid and Oxygen Reduction Reactions over Bimetallic, Trimetallic and Core–Shell-Structured Pd-Based Materials". Inorganics 7, n.º 3 (7 de março de 2019): 36. http://dx.doi.org/10.3390/inorganics7030036.

Texto completo da fonte

Resumo:

The structural design of nanosized electrocatalysts is extremely important for cathodic oxygen reduction reactions (ORR) and anodic oxidation reactions in small organic compounds in direct fuel cells. While Pt is still the most commonly used electrode material for ORR, the Pd electrocatalyst is a promising alternative to Pt, because it exhibits much higher electrocatalytic activity towards formic acid electrooxidation, and the electrocatalytic activity of ORR on the Pd electrode is the higher than that of all other precious metals, except for Pt. In addition, the mass activity of Pt in a core–shell structure for ORR can be improved significantly by using Pd and Pd-based materials as core materials. Herein, we review various nanoscale Pd-based bimetallic, trimetallic and core–shell electrocatalysts for formic acid oxidation and ORR of polymer electrolyte fuel cells (PEFCs). This review paper is separated into two major topics: the electrocatalytic activity towards formic acid oxidation over various Pd-based electrocatalysts, and the activity of ORR on Pd-based materials and Pd core–Pt shell structures.

Estilos ABNT, Harvard, Vancouver, APA, etc.

9

Banti, Angeliki, Kalliopi Maria Papazisi, Stella Balomenou e Dimitrios Tsiplakides. "Effect of Calcination Temperature on the Activity of Unsupported IrO2 Electrocatalysts for the Oxygen Evolution Reaction in Polymer Electrolyte Membrane Water Electrolyzers". Molecules 28, n.º 15 (2 de agosto de 2023): 5827. http://dx.doi.org/10.3390/molecules28155827.

Texto completo da fonte

Resumo:

Polymer electrolyte membrane (PEM) water electrolyzers suffer mainly from slow kinetics regarding the oxygen evolution reaction (OER). Noble metal oxides, like IrO2 and RuO2, are generally more active for OER than metal electrodes, exhibiting low anodic overpotentials and high catalytic activity. However, issues like electrocatalyst stability under continuous operation and cost minimization through a reduction in the catalyst loading are of great importance to the research community. In this study, unsupported IrO2 of various particle sizes (different calcination temperatures) were evaluated for the OER and as anode electrodes for PEM water electrolyzers. The electrocatalysts were synthesized by the modified Adams method, and the effect of calcination temperature on the properties of IrO2 electrocatalysts is investigated. Physicochemical characterization was conducted using X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET) surface area measurement, high-resolution transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS) analyses. For the electrochemical performance of synthesized electrocatalysts in the OER, cyclic voltammetry (CV) and linear sweep voltammetry (LSV) were conducted in a typical three-cell electrode configuration, using glassy carbon as the working electrode, which the synthesized electrocatalysts were cast on in a 0.5 M H2SO4 solution. The materials, as anode PEM water electrolysis electrodes, were further evaluated in a typical electrolytic cell using a Nafion®115 membrane as the electrolyte and Pt/C as the cathode electrocatalyst. The IrO2 electrocatalyst calcined at 400 °C shows high crystallinity with a 1.24 nm particle size, a high specific surface area (185 m2 g−1), and a high activity of 177 mA cm−2 at 1.8 V for PEM water electrolysis.

Estilos ABNT, Harvard, Vancouver, APA, etc.

10

Du, Hongfang, Qian Liu, Ningyan Cheng, Abdullah M. Asiri, Xuping Sun e Chang Ming Li. "Template-assisted synthesis of CoP nanotubes to efficiently catalyze hydrogen-evolving reaction". J. Mater. Chem. A 2, n.º 36 (2014): 14812–16. http://dx.doi.org/10.1039/c4ta02368d.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

11

Liu, Bin Hong, Zhou Peng Li e Seijirau Suda. "Electrocatalysts for the anodic oxidation of borohydrides". Electrochimica Acta 49, n.º 19 (agosto de 2004): 3097–105. http://dx.doi.org/10.1016/j.electacta.2004.02.023.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

12

Shi, Qiurong, Chengzhou Zhu, Dan Du e Yuehe Lin. "Robust noble metal-based electrocatalysts for oxygen evolution reaction". Chemical Society Reviews 48, n.º 12 (2019): 3181–92. http://dx.doi.org/10.1039/c8cs00671g.

Texto completo da fonte

Resumo:

The oxygen evolution reaction (OER) is a kinetically sluggish anodic reaction that requires rationalized compositions and structures for achieving highly efficient and reliable noble metal-based electrocatalysts in acidic electrolyte.

Estilos ABNT, Harvard, Vancouver, APA, etc.

13

Li, Xiumin, Xiaogang Hao, Abuliti Abudula e Guoqing Guan. "Nanostructured catalysts for electrochemical water splitting: current state and prospects". Journal of Materials Chemistry A 4, n.º 31 (2016): 11973–2000. http://dx.doi.org/10.1039/c6ta02334g.

Texto completo da fonte

Resumo:

The fundamentals of water electrolysis, current popular electrocatalysts developed for cathodic hydrogen evolution reaction (HER) and anodic oxygen evolution reaction (OER) in liquid electrolyte water electrolysis are reviewed and discussed.

Estilos ABNT, Harvard, Vancouver, APA, etc.

14

Bai, Jirong, Wangkai Zhou, Jinnan Xu, Pin Zhou, Yaoyao Deng, Mei Xiang, Dongsheng Xiang e Yaqiong Su. "RuO2 Catalysts for Electrocatalytic Oxygen Evolution in Acidic Media: Mechanism, Activity Promotion Strategy and Research Progress". Molecules 29, n.º 2 (22 de janeiro de 2024): 537. http://dx.doi.org/10.3390/molecules29020537.

Texto completo da fonte

Resumo:

Proton Exchange Membrane Water Electrolysis (PEMWE) under acidic conditions outperforms alkaline water electrolysis in terms of less resistance loss, higher current density, and higher produced hydrogen purity, which make it more economical in long-term applications. However, the efficiency of PEMWE is severely limited by the slow kinetics of anodic oxygen evolution reaction (OER), poor catalyst stability, and high cost. Therefore, researchers in the past decade have made great efforts to explore cheap, efficient, and stable electrode materials. Among them, the RuO2 electrocatalyst has been proved to be a major promising alternative to Ir-based catalysts and the most promising OER catalyst owing to its excellent electrocatalytic activity and high pH adaptability. In this review, we elaborate two reaction mechanisms of OER (lattice oxygen mechanism and adsorbate evolution mechanism), comprehensively summarize and discuss the recently reported RuO2-based OER electrocatalysts under acidic conditions, and propose many advanced modification strategies to further improve the activity and stability of RuO2-based electrocatalytic OER. Finally, we provide suggestions for overcoming the challenges faced by RuO2 electrocatalysts in practical applications and make prospects for future research. This review provides perspectives and guidance for the rational design of highly active and stable acidic OER electrocatalysts based on PEMWE.

Estilos ABNT, Harvard, Vancouver, APA, etc.

15

Li, Meng, Ping Liu e Radoslav R. Adzic. "Platinum Monolayer Electrocatalysts for Anodic Oxidation of Alcohols". Journal of Physical Chemistry Letters 3, n.º 23 (14 de novembro de 2012): 3480–85. http://dx.doi.org/10.1021/jz3016155.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

16

Balčiūnaitė, Aldona, Kush K. Upadhyay, Kristina Radinović, Diogo M. F. Santos, M. F. Montemor e Biljana Šljukić. "Steps towards highly-efficient water splitting and oxygen reduction using nanostructured β-Ni(OH)₂". RSC Advances 12, n.º 16 (2022): 10020–28. http://dx.doi.org/10.1039/d2ra00914e.

Texto completo da fonte

Resumo:

β-Ni(OH)2 nanoplatelets produced via a hydrothermal method exhibit good performance as trifunctional electrocatalysts for the ORR, OER, and HER in alkaline media along with excellent stability under cathodic/anodic polarisation conditions.

Estilos ABNT, Harvard, Vancouver, APA, etc.

17

Ting, Jyh-Ming, Hui-Chuan Chen e Thi Xuyen Nguyen. "Dicarboxylferrocene Ligand Promoted Structural Reconstruction in Bimetallic Nico-Based Metal Organic Framework for Energy-Saving H₂ Production via Urea Oxidation Reaction". ECS Meeting Abstracts MA2024-02, n.º 39 (22 de novembro de 2024): 2601. https://doi.org/10.1149/ma2024-02392601mtgabs.

Texto completo da fonte

Resumo:

Water electrolysis involving low energy barrier anodic urea oxidation reaction (UOR) is a promising way for hydrogen production. Among various UOR electrocatalysts, metal organic framework (MOF) shows unique features of high specific surface area, large porosity, and tunable electronic structure, providing abundant metal active sites for achieving high-performance electrocatalytic activity. Herein, we demonstrate redox-active dicarboxylferrocene (DFc) ligand modified NiCo-based MOF as an electrocatalyst toward UOR. The DFc ligand not only provides additional active sites for catalysis and intermediate adsorption/desorption, but also enhances the charge transfer, thus significantly improving the UOR activity. The NiCo-MOF-DFc demonstrates an outstanding UOR performance with an ultra-low potential of 1.23 V at 10 mA cm−2, a small Tafel slope of 50.8 mV dec−1, and an excellent stable durability. In-situ and ex-situ analyses, and density functional theory calculation reveal that the introduction of DFc ligand facilitates the reconstruction of MOF into metal oxyhydroxide, which are the active sites for the oxidative reaction. This study opens a new route for future development of advanced UOR electrocatalysts via ligand-engineering.

Estilos ABNT, Harvard, Vancouver, APA, etc.

18

Xia, Meng, Xinxin Yu, Zhuangzhuang Wu, Yuzhen Zhao, Lijuan Feng e Qi Chen. "Metal Imidazole-Modified Covalent Organic Frameworks as Electrocatalysts for Alkaline Oxygen Evolution Reaction". Molecules 29, n.º 21 (27 de outubro de 2024): 5076. http://dx.doi.org/10.3390/molecules29215076.

Texto completo da fonte

Resumo:

Since the product contains no carbon-based substances and can be driven by non-carbon-based electricity, electrocatalytic water splitting is considered to be among the most effective strategies for alleviating the energy crisis and environmental pollution. This process helps lower greenhouse gas emissions while also supporting the shift toward renewable energy sources. The anodic oxygen evolution reaction (OER) involves a more complex multi-electron transfer process, which is the principal limiting factor in overall water splitting. Extensive research has demonstrated that the controlled design of effective electrocatalysts can address this limitation. In this study, a previously unreported covalent organic framework material (COF-IM) was synthesized via a post-synthetic modification strategy. Notably, COF-IM contains imidazole nitrogen metal active sites. Transition metal-coordinated COF-IM@Co can function as a highly effective electrocatalyst, exhibiting a lower overpotential (403.8 mV@10 mA cm−2) in alkaline electrolytes, thereby highlighting its potential for practical applications in energy conversion technologies. This study offers new perspectives on the design and synthesis of COFs, while also making substantial contributions to the advancement and application of OER electrocatalysts.

Estilos ABNT, Harvard, Vancouver, APA, etc.

19

Scott, Soren B., Albert K. Engstfeld, Zenonas Jusys, Degenhart Hochfilzer, Nikolaj Knøsgaard, Daniel B. Trimarco, Peter C. K. Vesborg, R. Jürgen Behm e Ib Chorkendorff. "Anodic molecular hydrogen formation on Ru and Cu electrodes". Catalysis Science & Technology 10, n.º 20 (2020): 6870–78. http://dx.doi.org/10.1039/d0cy01213k.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

20

Yamada, Naohito, Damian Kowalski, Akira Koyama, Chunyu Zhu, Yoshitaka Aoki e Hiroki Habazaki. "High dispersion and oxygen reduction reaction activity of Co3O4 nanoparticles on platelet-type carbon nanofibers". RSC Advances 9, n.º 7 (2019): 3726–33. http://dx.doi.org/10.1039/c8ra09898k.

Texto completo da fonte

Resumo:

In this study, platelet-type carbon nanofibers prepared by the liquid phase carbonization of polymers in the pores of a porous anodic alumina template were used to prepare the Co₃O₄/carbon electrocatalysts.

Estilos ABNT, Harvard, Vancouver, APA, etc.

21

Lee, CHangsoo, Bonjae Koo, Sechan Lee, MinJoong Kim, Gisu Doo, Hyeonjung Park e Hyunseok Cho. "Development of Ba₃TiO₇-Supported IrO_x Electrocatalysts for Enhanced Mass Activity in the Acidic Oxygen Evolution Reaction". ECS Meeting Abstracts MA2024-01, n.º 34 (9 de agosto de 2024): 1755. http://dx.doi.org/10.1149/ma2024-01341755mtgabs.

Texto completo da fonte

Resumo:

Overcoming the challenge of developing highly durable and conductive support materials for Ir-based electrocatalysts in the acidic oxygen evolution reaction (OER) is difficult due to the highly corrosive conductions experienced during anodic process. In this research, we develop IrOx/Ba3TiO7 electrocatalysts, which employ Ba3TiO7 as a new support material, to minimize loading amount of iridium. We also try to fabricated Ba3TiO(7-x) support material with abundant oxygen vacancies for enhanced conductivity of the support material. As a results, the IrOx/Ba3TiO7 electrocatalysts demonstrated remarkable OER performances and enhanced mass activity compared to unsupported IrOx electrocatalysts. Through a combination of physical and chemical analyses, It was elucidated that the excellent thermodynamic stability and electrical conductivity of Ba3TiO7 effectively enhanced the mass activity of IrOx/Ba3TiO7 electrocatalysts. These finding provide further insight into new category of anode support materials for proton exchange membrane water electrolyzer.

Estilos ABNT, Harvard, Vancouver, APA, etc.

22

Protsenko, Vyacheslav. "Electrochemical Surface Treatment of Ni–Cu Alloy in a Deep Eutectic Solvent to form High Performance Electrocatalysts for Hydrogen Production". Journal of Mineral and Material Science (JMMS) 3, n.º 2 (18 de junho de 2022): 1–2. http://dx.doi.org/10.54026/jmms/1037.

Texto completo da fonte

Resumo:

Anodic electrochemical treatment of nickel-copper alloy (45 wt.% Ni) was conducted in a deep eutectic solvent, ethaline (a eutectic mixture of choline chloride and ethylene glycol). The electrochemical behavior of the Ni–Cu alloy was investigated by means of linear voltammetry technique. Anodic treatment of nickel-copper alloy in ethaline was stated to enhance the electrocatalytic activity towards hydrogen evolution reaction in alkaline water electrolysis. The results obtained can be used to develop new electrocatalysts for hydrogen synthesis in hydrogen energy.

Estilos ABNT, Harvard, Vancouver, APA, etc.

23

Li, Guixian, Shoudeng Wang, Hongwei Li, Peng Guo, Yanru Li, Dong Ji e Xinhong Zhao. "Carbon-Supported PdCu Alloy as Extraordinary Electrocatalysts for Methanol Electrooxidation in Alkaline Direct Methanol Fuel Cells". Nanomaterials 12, n.º 23 (26 de novembro de 2022): 4210. http://dx.doi.org/10.3390/nano12234210.

Texto completo da fonte

Resumo:

Palladium (Pd) nanostructures are highly active non-platinum anodic electrocatalysts in alkaline direct methanol fuel cells (DMFCs), and their electrocatalytic performance relies highly on their morphology and composition. This study reports the preparation, characterizations, and electrocatalytic properties of palladium-copper alloys loaded on the carbon support. XC-72 was used as a support, and hydrazine hydrate served as a reducing agent. PdxCuy/XC-72 nanoalloy catalysts were prepared in a one-step chemical reduction process with different ratios of Pd and Cu. A range of analytical techniques was used to characterize the microstructure and electronic properties of the catalysts, including transmission electron microscopy (TEM), X-ray diffractometry (XRD), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma emission spectroscopy (ICP-OES). Benefiting from excellent electronic structure, Pd3Cu2/XC-72 achieves higher mass activity enhancement and improves durability for MOR. Considering the simple synthesis, excellent activity, and long-term stability, PdxCuy/XC-72 anodic electrocatalysts will be highly promising in alkaline DMFCs.

Estilos ABNT, Harvard, Vancouver, APA, etc.

24

Moreno-Hernandez, Ivan A. "(Invited) Direct Observation of Nanoscale Heterogeneity in Ruthenium Oxide Rutile Nanocrystals for the Oxygen Evolution Reaction via Liquid Phase Transmission Electron Microscopy". ECS Meeting Abstracts MA2024-02, n.º 61 (22 de novembro de 2024): 4112. https://doi.org/10.1149/ma2024-02614112mtgabs.

Texto completo da fonte

Resumo:

Oxygen-evolving electrocatalysts in acid undergo structural changes that result in a loss of activity, which necessitates high catalyst loadings of precious noble metal oxides. A fundamental understanding of the structural dynamics at the electrode/electrolyte interface that occur during oxygen evolution is necessary to design the next generation of electrocatalyst materials with improved performance. The Moreno-Hernandez Laboratory utilizes liquid phase transmission electron microscopy to directly observe the stability of single-nanocrystalline and highly faceted metal oxide nanocrystals under anodic conditions in acidic electrolytes. Our studies reveal the distribution of stability relationships between different crystallographic facets for nanocrystalline materials, and enable the direct determination of nanoscale heterogeneity at the single nanocrystal level. Substantial stability differences are observed across multiple nanocrystals, which are correlated to variability in the nanoscale strain present in individual nanocrystals. These studies suggest that nanoscale heterogeneity occluded in conventional bulk-scale analysis techniques substantially influences stability under relevant operation conditions, and provide crucial information for the design of resilient electrocatalyst materials.

Estilos ABNT, Harvard, Vancouver, APA, etc.

25

Kuang, Yun, Michael J. Kenney, Yongtao Meng, Wei-Hsuan Hung, Yijin Liu, Jianan Erick Huang, Rohit Prasanna et al. "Solar-driven, highly sustained splitting of seawater into hydrogen and oxygen fuels". Proceedings of the National Academy of Sciences 116, n.º 14 (18 de março de 2019): 6624–29. http://dx.doi.org/10.1073/pnas.1900556116.

Texto completo da fonte

Resumo:

Electrolysis of water to generate hydrogen fuel is an attractive renewable energy storage technology. However, grid-scale freshwater electrolysis would put a heavy strain on vital water resources. Developing cheap electrocatalysts and electrodes that can sustain seawater splitting without chloride corrosion could address the water scarcity issue. Here we present a multilayer anode consisting of a nickel–iron hydroxide (NiFe) electrocatalyst layer uniformly coated on a nickel sulfide (NiSx) layer formed on porous Ni foam (NiFe/NiSx-Ni), affording superior catalytic activity and corrosion resistance in solar-driven alkaline seawater electrolysis operating at industrially required current densities (0.4 to 1 A/cm2) over 1,000 h. A continuous, highly oxygen evolution reaction-active NiFe electrocatalyst layer drawing anodic currents toward water oxidation and an in situ-generated polyatomic sulfate and carbonate-rich passivating layers formed in the anode are responsible for chloride repelling and superior corrosion resistance of the salty-water-splitting anode.

Estilos ABNT, Harvard, Vancouver, APA, etc.

26

Osman, Siti Hasanah, Siti Kartom Kamarudin, Sahriah Basri e Nabila A. Karim. "Anodic Catalyst Support via Titanium Dioxide-Graphene Aerogel (TiO2-GA) for A Direct Methanol Fuel Cell: Response Surface Approach". Catalysts 13, n.º 6 (14 de junho de 2023): 1001. http://dx.doi.org/10.3390/catal13061001.

Texto completo da fonte

Resumo:

The direct methanol fuel cell (DMFC) has the potential for portable applications. However, it has some drawbacks that make commercialisation difficult owing to its poor kinetic oxidation efficiency and non-economic cost. To enhance the performance of direct methanol fuel cells, various aspects should be explored, and operational parameters must be tuned. This research was carried out using an experimental setup that generated the best results to evaluate the effectiveness of these variables on electrocatalysis performance in a fuel cell system. Titanium dioxide-graphene aerogel (TiO2-GA) has not yet been applied to the electrocatalysis area for fuel cell application. As a consequence, this research is an attempt to boost the effectiveness of direct methanol fuel cell electrocatalysts by incorporating bifunctional PtRu and TiO2-GA. The response surface methodology (RSM) was used to regulate the best combination of operational parameters, which include the temperature of composite TiO2-GA, the ratio of Pt to Ru (Pt:Ru), and the PtRu catalyst composition (wt%) as factors (input) and the current density (output) as a response for the optimisation investigation. The mass activity is determined using cyclic voltammetry (CV). The best-operating conditions were determined by RSM-based performance tests at a composition temperature of 202 °C, a Pt/Ru ratio of (1.1:1), and a catalyst composition of 22%. The best response is expected to be 564.87 mA/mgPtRu. The verification test is performed, and the average current density is found to be 568.15 mA/mgPtRu. It is observed that, after optimisation, the PtRu/TiO2-GA had a 7.1 times higher current density as compared to commercial PtRu. As a result, a titanium dioxide-graphene aerogel has potential as an anode electrocatalyst in direct methanol fuel cells.

Estilos ABNT, Harvard, Vancouver, APA, etc.

27

Zhen, Janet, Tucker Forbes, Timothy Lin, Jinhui Tao, Mark H. Engelhard e Jingjing Qiu. "Investigation of Plasmon-Mediated Oxygen Evolution Reaction". ECS Meeting Abstracts MA2024-01, n.º 53 (9 de agosto de 2024): 2868. http://dx.doi.org/10.1149/ma2024-01532868mtgabs.

Texto completo da fonte

Resumo:

To achieve a carbon-neutral future, sustainable energy is needed through storing energy through its chemical bond. Water electrolysis, an exemplary form of electrocatalysis, presents an example of storing energy within chemical bonds of the high-energy hydrogen gas. Nevertheless, the anodic reaction involved in the oxygen evolution reaction (OER) poses limitations on the overall rate of the process. Plasmonic gold nanoparticles (Au NPs) have been added to enhance the charge transfer at the interface of the OER electrocatalysts and electrolyte under light illumination.1-3 However, the mechanistic understanding of how the Au NPs on the photo-assisted electrochemical process is still lacking. We applied a model system of plasmonic Au electrode with nickel (Ni) and cobalt (Co)-based OER electrocatalyst to investigate the plasmon-mediated OER process. The composite system has been characterized with XPS, AFM, (photo)electrochemical and spectroscopic characterizations. Our preliminary data shows that the electrodeposited plasmonic Au electrode is free of surfactant and the resonant light illumination could modulate the electrochemical properties of the Au electrode and the Ni- and Co-based electrocatalysts in the alkaline electrolytes. Liu, G.; Li, P.; Zhao, G.; Wang, X.; Kong, J.; Liu, H.; Zhang, H.; Chang, K.; Meng, X.; Kako, T.; Ye, J. Promoting Active Species Generation by Plasmon-Induced Hot-Electron Excitation for Efficient Electrocatalytic Oxygen Evolution. Am. Chem. Soc. 2016, 138(29), 9128–9136. Wang, M.; Wang, P.; Li, C.; Li, H.; Jin, Y. Boosting Electrocatalytic Oxygen Evolution Performance of Ultrathin Co/Ni-MOF Nanosheets via Plasmon-Induced Hot Carriers. ACS Appl. Mater. Interfaces 2018, 10(43), 37095–37102. Zeng, X.; Choi, S. M.; Bai, Y.; Jang, M. J.; Yu, R.; Cho, H.-S.; Kim, C.-H.; Myung, N. V.; Yin, Y. Plasmon-Enhanced Oxygen Evolution Catalyzed by Fe2N-Embedded TiOxNy ACS Appl. Energy Mater. 2020, 3(1), 146–151.

Estilos ABNT, Harvard, Vancouver, APA, etc.

28

Chen, Dayi, Fabien Giroud e Shelley D. Minteer. "Nickel Cysteine Complexes as Anodic Electrocatalysts for Fuel Cells". Journal of The Electrochemical Society 161, n.º 9 (2014): F933—F939. http://dx.doi.org/10.1149/2.0811409jes.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

29

Sun, Miguang, e Jiajun Gu. "Progress in Preparation and Research of Water Electrolysis Catalyst for Transition Metal Phosphide". Journal of Physics: Conference Series 2152, n.º 1 (1 de janeiro de 2022): 012063. http://dx.doi.org/10.1088/1742-6596/2152/1/012063.

Texto completo da fonte

Resumo:

Abstract Confronted with growing energy crisis and environmental challenges, water electrolysis for hydrogen production can provide high-density, clean and renewable energy, but limited by sluggish kinetics of two half reaction, anodic oxygen evolution reaction (OER) and cathodic hydrogen evolution reaction(HER). Noble-metal-based electrocatalysts can decrease overpotential and accelerate kinetics dramatically, but limited by its scarcity and high cost. Transitional metal catalysts are abundant, low cost and have potential to become excellent catalyst due to unique electronic structure. Beginning from basic principle of electrocatalysis, this paper focuses on the synthesis method of transitional metal phosphide (TMP), and further discusses modification methods of TMP, including phase tuning, element doping/alloying, interfacial/structural engineering and three-dimensional architecture. Finally, the challenges of TMP are analyzed and future research focuses are prospected.

Estilos ABNT, Harvard, Vancouver, APA, etc.

30

Davari, Elaheh, e Douglas G. Ivey. "Mn-Co oxide/PEDOT as a bifunctional electrocatalyst for oxygen evolution/reduction reactions". MRS Proceedings 1777 (2015): 1–6. http://dx.doi.org/10.1557/opl.2015.449.

Texto completo da fonte

Resumo:

ABSTRACTBifunctional electrocatalysts, which facilitate the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER), are vital components in advanced metal-air batteries. Results are presented for carbon-free, nanocrystalline, rod-like, Mn-Co oxide/PEDOT bifunctional electrocatalysts, prepared by template-free sequential anodic electrodeposition. Electrochemical characterization of synthesized electrocatalysts, with and without a conducting polymer (PEDOT) coating, was performed using cyclic voltammetry (CV) and linear sweep voltammetry (LSV). In addition, microstructural characterization was conducted using SEM, TEM, STEM and XPS. Mn-Co oxide/PEDOT showed improved ORR/OER performance relative to Mn-Co oxide and PEDOT. On the basis of rotating disk electrode (RDE) experiments, Mn-Co oxide/PEDOT displayed the desired 4-electron transfer oxygen reduction pathway. Comparable ORR activity and superior OER activity relative to commercial Pt/C were observed.

Estilos ABNT, Harvard, Vancouver, APA, etc.

31

Chen, D., G. G. W. Lee e S. D. Minteer. "Utilizing DNA for Electrocatalysis: DNA-Nickel Aggregates as Anodic Electrocatalysts for Methanol, Ethanol, Glycerol, and Glucose". ECS Electrochemistry Letters 2, n.º 2 (20 de novembro de 2012): F9—F13. http://dx.doi.org/10.1149/2.002302eel.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

32

Kim, Min Gi, Ashish Gaur, Jin Uk Jang, Kyeong-Han Na, Won-Youl Choi e HyukSu Han. "High-Entropy Carbonates (Ni-Mn-Co-Zn-Cr-Fe) as a Promising Electrocatalyst for Alkalized Seawater Oxidation". International Journal of Energy Research 2024 (6 de março de 2024): 1–16. http://dx.doi.org/10.1155/2024/9996841.

Texto completo da fonte

Resumo:

Direct seawater splitting has attracted considerable attention as an alternative to conventional alkaline water electrolysis because the former avoids the use of limited freshwater resources. However, several challenges must be overcome to realize direct seawater electrolysis. Most importantly, electrocatalysts for the anodic oxygen evolution reaction (OER) should exhibit high activity, stability, and selectivity in highly corrosive environments with abundant chloride ions. In this study, we developed high-entropy carbonate (HEC) as a promising electrocatalyst for seawater oxidation. In HECs, physicochemical interactions among different elements can effectively suppress the corrosion of OER active sites, while polyanionic CO32- can act as a corrosion-protective species by repelling negatively charged chloride ions during electrolysis. Consequently, HECs demonstrate outstanding catalytic activity, stability, and selectivity for seawater oxidation, surpassing those of ternary, quaternary, and quinary carbonates and even benchmark IrO2 catalysts.

Estilos ABNT, Harvard, Vancouver, APA, etc.

33

MORITA, Masayuki, Hideo KIJIMA e Yoshiharu MATSUDA. "Anodic Oxidation of Formic Acid at Nafion-Modified Palladium Electrocatalysts". Denki Kagaku oyobi Kogyo Butsuri Kagaku 60, n.º 6 (5 de junho de 1992): 554–56. http://dx.doi.org/10.5796/electrochemistry.60.554.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

34

Sriphathoorat, Rinrada, Kai Wang e Pei Kang Shen. "Trimetallic Hollow Pt–Ni–Co Nanodendrites as Efficient Anodic Electrocatalysts". ACS Applied Energy Materials 2, n.º 2 (15 de janeiro de 2019): 961–65. http://dx.doi.org/10.1021/acsaem.8b01741.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

35

Bosse, Jan, e Andrew Akbashev. "Probing Lattice Oxygen Oxidation in Perovskite Electrocatalysts By Resonant Inelastic X-Ray Scattering". ECS Meeting Abstracts MA2023-01, n.º 47 (28 de agosto de 2023): 2517. http://dx.doi.org/10.1149/ma2023-01472517mtgabs.

Texto completo da fonte

Resumo:

During water electrolysis, the hydrogen evolution reaction that generates hydrogen gas is unavoidably accompanied by the anodic reaction that generates oxygen via the oxygen evolution reaction (OER). However, under OER conditions, many electrocatalysts undergo structural degradation and can become amorphous. Lattice oxygen oxidation was proposed as one of the possible causes for amorphization of perovskite oxides. However, because lattice oxygen oxidation is notoriously challenging to probe in experiments, its unambiguous detection in oxide electrocatalysts has been elusive so far. Here, I will show how oxygen oxidation can be detected in single-crystalline (model) oxide electrocatalysts using high-resolution resonant inelastic X-ray scattering (RIXS). Specifically, I will present our case study of perovskite materials where the emergence of oxidized oxygen depends on the transition metal and the applied potential. An insight into the chemical environment of the oxidized oxygen and how it can be accommodated in the perovskite lattice will be provided based on the results of DFT and molecular dynamics. Finally, I will discuss how lattice oxygen oxidation is related to the degradation of oxide electrocatalysts during OER.

Estilos ABNT, Harvard, Vancouver, APA, etc.

36

Rivera-Maldonado, Ricardo Andres, Anthony Gironda, Jared E. Abramson, Abraham Varughese, Gerald Seidler e Brandi Michelle Cossairt. "Probing the Stability of Ni₂P Nanoparticle Electrocatalysts via Operando Benchtop X-Ray Absorption Spectroscopy". ECS Meeting Abstracts MA2024-02, n.º 60 (22 de novembro de 2024): 4062. https://doi.org/10.1149/ma2024-02604062mtgabs.

Texto completo da fonte

Resumo:

The electrification of the petrochemical industry will greatly reduce greenhouse gas emissions in the manufacturing of commodity chemicals; however, electrification on a global scale is only achievable using earth-abundant materials for electrocatalysis in place of state-of-the-art catalysts made from precious metals. A promising catalyst that has been used for industrial hydrodesulfurization and electrocatalytic hydrogen evolution, nitrate reduction, carbon dioxide reduction, and oxygen evolution is Ni2P. Ni2P and other transition metal phosphides benefit from active site ensembles that moderate the binding of reaction intermediates, making them promising electrocatalysts for reactions beyond the ones listed, especially other hydrogenation reactions. However, Ni2P and other TMPs are susceptible to oxidation, which can lead to catalyst degradation and loss in certain conditions. Stability is an important part of catalysis; therefore, it is important to understand the degradation mechanism of Ni2P in order to mitigate corrosion, accurately predict surface reactivity, and prepare Ni2P for industrial electrocatalysis. Previous reports on Ni-P alloys found passivation regimes through anodic polarization but others saw complete dissolution at more oxidizing potentials. Bulk nickel phosphides have been shown to have a passivated surface, and characterization, often limited to ex-situ spectroscopy after the fact, has shown that the surface is composed of nickel hydroxides, phosphates, and oxyhydroxides. In the present work, operando Ni K-edge X-ray absorption spectroscopy and polarization are combined to understand the electrochemical degradation of Ni2P nanoparticles. Ni2P nanoparticles were synthesized by heating NiCl2 and tris(diethylamino)phosphine in oleylamine and thermally annealed at 450 °C under 5% H2/95% N2. Transmission-mode Ni K-edge X-ray absorption spectroscopy was conducted on benchtop spectrometers (easyXAFS) using a 3D-printed electrochemical cell designed for operando spectroscopy. Nanoparticles maximize surface to bulk atom ratio, which is beneficial both for electrocatalysis, less atoms are necessary to have the same number of active sites, and for X-ray absorption, spectra are more surface sensitive. The use of a benchtop spectrometer offers the flexibility to iterate on experiments on the fly and the power to acquire synchrotron quality data on a routine basis. Preliminary results in neutral phosphate buffered electrolyte indicate that Ni2P significantly oxidizes and dissolves at and beyond 0.8 V vs RHE which agrees with anodic polarization corrosion experiments. Ongoing work extends anodic polarization experiments to acidic and basic pH and probes the potentials at which oxidation is no longer reversible. We hypothesize that dissolution will be less severe with increased pH and reduction of oxidized species to Ni2P will no longer be possible after the onset of Ni dissolution.

Estilos ABNT, Harvard, Vancouver, APA, etc.

37

Eskandrani, Areej A., Shimaa M. Ali e Hibah M. Al-Otaibi. "Study of the Oxygen Evolution Reaction at Strontium Palladium Perovskite Electrocatalyst in Acidic Medium". International Journal of Molecular Sciences 21, n.º 11 (27 de maio de 2020): 3785. http://dx.doi.org/10.3390/ijms21113785.

Texto completo da fonte

Resumo:

The catalytic activity of Sr2PdO3, prepared through the sol-gel citrate-combustion method for the oxygen evolution reaction (OER) in a 0.1 M HClO4 solution, was investigated. The electrocatalytic activity of Sr2PdO3 toward OER was assessed via the anodic potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The glassy carbon modified Sr2PdO3 (GC/Sr2PdO3) electrode exhibited a higher electrocatalytic activity, by about 50 times, in comparison to the unmodified electrode. The order of the reaction was close to unity, which indicates that the adsorption of the hydroxyl groups is a fast step. The calculated activation energy was 21.6 kJ.mol−1, which can be considered a low value in evaluation with those of the reported OER electrocatalysts. The Sr2PdO3 perovskite portrayed a high catalyst stability without any probability of catalyst poisoning. These results encourage the use of Sr2PdO3 as a candidate electrocatalyst for water splitting reactions.

Estilos ABNT, Harvard, Vancouver, APA, etc.

38

Giziński, Damian, Anna Brudzisz, Janaina S. Santos, Francisco Trivinho-Strixino, Wojciech J. Stępniowski e Tomasz Czujko. "Nanostructured Anodic Copper Oxides as Catalysts in Electrochemical and Photoelectrochemical Reactions". Catalysts 10, n.º 11 (17 de novembro de 2020): 1338. http://dx.doi.org/10.3390/catal10111338.

Texto completo da fonte

Resumo:

Recently, nanostructured copper oxides formed via anodizing have been intensively researched due to their potential catalytic applications in emerging issues. The anodic Cu2O and CuO nanowires or nanoneedles are attractive photo- and electrocatalysts since they show wide array of desired electronic and morphological features, such as highly-developed surface area. In CO2 electrochemical reduction reaction (CO2RR) copper and copper-based nanostructures indicate unique adsorption properties to crucial reaction intermediates. Furthermore, anodized copper-based materials enable formation of C2+ hydrocarbons and alcohols with enhanced selectivity. Moreover, anodic copper oxides provide outstanding turnover frequencies in electrochemical methanol oxidation at lowered overpotentials. Therefore, they can be considered as precious metals electrodes substituents in direct methanol fuel cells. Additionally, due to the presence of Cu(III)/Cu(II) redox couple, these materials find application as electrodes for non-enzymatic glucose sensors. In photoelectrochemistry, Cu2O-CuO heterostructures of anodic copper oxides with highly-developed surface area are attractive for water splitting. All the above-mentioned aspects of anodic copper oxides derived catalysts with state-of-the-art background have been reviewed within this paper.

Estilos ABNT, Harvard, Vancouver, APA, etc.

39

Haidar, Fatima, Mathieu Maas, Andrea Piarristeguy, Annie Pradel, Sara Cavaliere e Marie-Christine Record. "Ultra-Thin Platinum Deposits by Surface-Limited Redox Replacement of Tellurium". Nanomaterials 8, n.º 10 (15 de outubro de 2018): 836. http://dx.doi.org/10.3390/nano8100836.

Texto completo da fonte

Resumo:

Platinum is the most employed electrocatalyst for the reactions taking place in energy converters, such as the oxygen reduction reaction in proton exchange membrane fuel cells, despite being a very low abundant element in the earth’s crust and thus extremely expensive. The search for more active electrocatalysts with ultra-low Pt loading is thus a very active field of investigation. Here, surface-limited redox replacement (SLRR) that utilizes the monolayer-limited nature of underpotential deposition (UPD) was used to prepare ultrathin deposits of Pt, using Te as sacrificial metal. Cyclic voltammetry and anodic potentiodynamic scanning experiments have been performed to determine the optimal deposition conditions. Physicochemical and electrochemical characterization of the deposited Pt was carried out. The deposit comprises a series of contiguous Pt islands that form along the grain interfaces of the Au substrate. The electrochemical surface area (ECSA) of the Pt deposit obtained after 5 replacements, estimated to be 18 m2/g, is in agreement with the ECSA of extended surface catalysts on flat surfaces.

Estilos ABNT, Harvard, Vancouver, APA, etc.

40

Wang, Tian-Jiao, Guang-Rui Xu, Hui-Ying Sun, Hao Huang, Fu-Min Li, Pei Chen e Yu Chen. "Anodic hydrazine electrooxidation boosted overall water electrolysis by bifunctional porous nickel phosphide nanotubes on nickel foam". Nanoscale 12, n.º 21 (2020): 11526–35. http://dx.doi.org/10.1039/d0nr02196b.

Texto completo da fonte

Estilos ABNT, Harvard, Vancouver, APA, etc.

41

Kong, Ling Bin, Xiao Wei Wang, Ru Tao Wang, Yong Chun Luo e Long Kang. "Ag Catalyst on Ordered Mesoporous Carbon with High Electro-Oxidation Activity for Formaldehyde". Advanced Materials Research 347-353 (outubro de 2011): 494–97. http://dx.doi.org/10.4028/www.scientific.net/amr.347-353.494.

Texto completo da fonte

Resumo:

Ag nanoparticles have been fabricated on the surface of CMK-3 mesoporous carbon through an immersion-electrodeposition (IE) technique. Transmission electron microscopy analysis indicated that it was a facile approach to electrochemically prepare nano-sized Ag clusters. Electrochemical experiments showed that Ag nanoproducts were efficient electrocatalysts for anodic oxidation of formaldehyde in alkaline solutions, and as the reduced of the potential value, the electrocatalytic peak current density for the formaldehyde electro-oxidation reaction was increased gradually. Also, the electrocatalytic activity of Ag/CMK-3 nanocatalysts for formaldehyde electro-oxidation is higher than that of Ag/XC-72 nanocatalysts. These findings represented a significant step toward the implementation of individual Ag/CMK-3 nanocatalysts as anodic materials in fuel cells and sensors.

Estilos ABNT, Harvard, Vancouver, APA, etc.

42

Choi, Yun-Hyuk. "Electrocatalytic Activities of High-Entropy Oxides for the Oxygen Evolution Reaction". ECS Meeting Abstracts MA2023-02, n.º 54 (22 de dezembro de 2023): 2604. http://dx.doi.org/10.1149/ma2023-02542604mtgabs.

Texto completo da fonte

Resumo:

Electrocatalytic water-splitting hydrogen generation consists of the cathodic hydrogen evolution reaction (HER) and the anodic oxygen evolution reaction (OER), where the four-electron-relevant OER is the rate-determining step. So far, there have been many efforts to substitute for the highly expensive noble-metal electrocatalysts (platinum, ruthenium or rhodium oxides, etc.). Transition-metal oxides based on Co, Ni, Mn, and V have been suggested as such alternatives, due to their low cost, high efficiency, and high stability. Recently, since the compositional diversity can provide a new breakthrough in that area, a high-entropy oxide (HEO) with five transition-metal cations has been suggested as a promising electrocatalyst toward the OER. In our studies, two kinds of HEOs were prepared and their OER activities were investigated. To begin with, for the (Mg0.2Fe0.2Co0.2Ni0.2Cu0.2)O, the effect of constituent cations on the OER activity was unveiled. Furthermore, a core cation driving the high OER activity was found. For it, the medium-entropy oxides (MEOs) with four cations are prepared by subtracting each cation (Mg, Fe, Co, Ni, or Cu) from the HEO, exhibiting homogeneous morphology, equiatomic composition, and single-phase rocksalt structure. As a result, it is found that the highest concentration of Co3+ in the MEO (w/o Cu) leads to the best OER activity, and thus Co3+ is the core ion driving the high OER activity. Furthermore, it is regarded that Cu2+ ions prevent the conversion of Co or Fe cations from 2+ to 3+ in the HEO and MEOs. Accordingly, maximizing the concentration of Co3+ within electrocatalysts is suggested as an effective design strategy for the high-efficiency electrocatalysts based on high or medium entropy materials. Secondly, the relationship between structure and OER activity was elucidated for the (Mg0.2Fe0.2Co0.2Zn0.2Cu0.2)O with a temperature-dependent rocksalt-to-spinel transition.

Estilos ABNT, Harvard, Vancouver, APA, etc.

43

Alaufey, Rayan, e Maureen H. Tang. "A Mechanistic Investigation of Electrochemical Ozone Production Using Nickel and Antimony Doped Tin Oxide in Non-Aqueous Electrolytes". ECS Meeting Abstracts MA2022-02, n.º 64 (9 de outubro de 2022): 2389. http://dx.doi.org/10.1149/ma2022-02642389mtgabs.

Texto completo da fonte

Resumo:

Electrochemical water splitting to produce hydrogen has attracted great interest as an environmentally-friendly renewable fuel. While cathodic hydrogen evolution (HER) is a relatively fast process that produces a valuable chemical, the anodic oxygen evolution reaction (OER) is a slow process that adds little to no economic value to water splitting.1,2 Generating a high-performance oxidizer such as ozone instead of oxygen could make water splitting more economically feasible because of the added value of ozone. However, electrochemical ozone production (EOP) catalysts are typically hindered by low current efficiencies, poor selectivity, low stability, and high energy demands, which limit the industrial application of this reaction.3,4 Further improvements in catalyst performance could be achieved by better understanding the mechanism of ozone production. Nickel and antimony doped tin oxide (Ni/Sb-SnO2, NATO) is currently reported to have the highest EOP current efficiency at room temperature. However, the mechanism of EOP on NATO electrodes has not yet been established. A primary complication when studying the mechanism of EOP using NATO electrocatalysts in water is that oxygen atoms in the ozone molecule can originate from sources other than water, such as dissolved molecular oxygen or the electrocatalyst oxide lattice.1,5,6 In this work, lattice oxygen participation in EOP is investigated by replacing water with acetonitrile, a polar aprotic solvent without oxygen atoms. Our results show that ozone can be generated in acetonitrile in similar quantities as aqueous conditions.2 These quantities are inconsistent with a 6-electron process based on calculated current efficiencies. Furthermore, the addition of small quantities of water is shown to have a negative impact on ozone generation. The origin of this impact is thought to not be mechanistic in nature. Instead, we suggest that adding water to the mixture leads to the generation of hydroxide ions which act as ozone scavengers. To our knowledge, this is the first report of electrochemical ozone production in a non-aqueous solvent. Future work will more conclusively determine the origin of oxygen atoms using isotopic labeling. Furthermore, the ability of nonaqueous solvents to stabilize reactive oxygen species and impact selectivity will be investigated. Utilizing the knowledge gained by studying ozone generation in nonaqueous solvents, it might be possible to design a better EOP system which could enhance the applicability of this reaction. (1) Lees, C. M.; Lansing, J. L.; Morelly, S. L.; Lee, S. E.; Tang, M. H. Ni- and Sb-Doped SnO2 Electrocatalysts with High Current Efficiency for Ozone Production via Electrodeposited Nanostructures. J. Electrochem. Soc. 2018, 165 (16), E833. https://doi.org/10.1149/2.0051816jes. (2) James L. Lansinga±, Lingyan Zhaob, Tana Siboonruanga, N. Harsha Attanayakea, Angela B. Leob, Peter Fatourosb, So Min Parkc, Kenneth R. Grahamc, John A. Keithb, Maureen Tang*a. Gd-Ni-Sb-SnO2 Electrocatalysts for Active and Selective Ozone Production. (3) Christensen, P. A.; Attidekou, P. S.; Egdell, R. G.; Maneelok, S.; Manning, D. A. C.; Palgrave, R. Identification of the Mechanism of Electrocatalytic Ozone Generation on Ni/Sb-SnO 2. J. Phys. Chem. C 2017, 121 (2), 1188–1199. https://doi.org/10.1021/acs.jpcc.6b10521. (4) Wang, Y.-H.; Chen, Q.-Y. Anodic Materials for Electrocatalytic Ozone Generation. Int. J. Electrochem. 2013, 2013, 1–7. https://doi.org/10.1155/2013/128248. (5) Jiang, W.; Wang, S.; Liu, J.; Zheng, H.; Gu, Y.; Li, W.; Shi, H.; Li, S.; Zhong, X.; Wang, J. Lattice Oxygen of PbO 2 Induces Crystal Facet Dependent Electrochemical Ozone Production. J. Mater. Chem. A 2021, 9 (14), 9010–9017. https://doi.org/10.1039/D0TA12277G. (6) Feng, J.; Johnson, D. C.; Lowery, S. N.; Carey, J. J. Electrocatalysis of Anodic Oxygen‐Transfer Reactions: Evolution of Ozone. J. Electrochem. Soc. 1994, 141 (10), 2708–2711. https://doi.org/10.1149/1.2059184.

Estilos ABNT, Harvard, Vancouver, APA, etc.

44

Meeying, Siriporn, Pinsuda Viravathana, Atchana Wongchaisuwat e Siree Tangbunsuk. "Synthesis and Characterization of PdCoNi Nanocomposites Supported on Graphene as Anodic Electrocatalysts for Methanol Oxidation in Direct Methanol Fuel Cell". Key Engineering Materials 658 (julho de 2015): 190–94. http://dx.doi.org/10.4028/www.scientific.net/kem.658.190.

Texto completo da fonte

Resumo:

PdCoNi nanocomposites supported on graphene (PdCoNi/G) have been obtained from chemical reduction of metal catalysts and graphite oxide (GO) with a strong reducing agent, followed by calcination at high temperature under N2 condition, and used for electrooxidation of methanol in direct methanol fuel cell. The morphologies and structural properties of electrocatalysts were examined by scanning electron microscopy (SEM) and X-ray diffraction (XRD). X-ray spectroscopy techniques (X-ray photoelectron spectroscopy XPS) was used to investigate the chemical state of the synthesized catalysts. The results of Pd XPS spectra showed the metallic Pd and PdO phases for precalcined and calcined PdCoNi/G nanocomposite, respectively. The X-ray measurement of Co and Ni displayed the various metallic oxides in synthesized electrocatalysts. For electrochemical analysis, cyclic voltammetry (CV) and chronoamperometry (CA) indicated that the PdCoNi/G nanocomposites enhanced the methanol oxidation, compared to the lower activity in the calcined electrocatalysts.

Estilos ABNT, Harvard, Vancouver, APA, etc.

45

Castello, Carolina, Maria Vincenza Pagliaro, Francesco Bartoli, Marco Bellini, Tailor Peruzzolo, Enrico Berretti, Hamish Andrew Miller e Francesco Vizza. "Silver-M-Phathalocyanine (M= Co,Fe,Cu) Electrocatalysts for Oxygen Reduction Reaction in H₂/O₂ Anion Exchange Membrane Fuel Cells". ECS Meeting Abstracts MA2023-02, n.º 41 (22 de dezembro de 2023): 2023. http://dx.doi.org/10.1149/ma2023-02412023mtgabs.

Texto completo da fonte

Resumo:

In the transition from fossil fuels to clean energy sources, H2 plays a key role due to its high energy density, and direct conversion to electricity in fuel cells (FCs). FCs are devices that allow the clean conversion of chemical energy into electrical energy. In H2/O2 fuel cell the hydrogen oxidation reaction (HOR) occurs at the anodic electrode, while at the cathodic side oxygen is reduced into water (ORR). The electrodes are separated by a conductive membrane, that could exchange protons (Proton Exchange Membrane, PEM) or anions (Anion Exchange Membrane, AEM) to maintain the electro-neutrality of the system. AEMFCs are an attractive alternative to PEMFCs, thanks to the alkaline noncorrosive enviroment that allows the use of cheaper structural materials such as non-noble metal electrocatalysts. This work is centred on the study of silver (Ag) nanostructured electrocatalysts in ORR for the realization of a platinum-free AEMFCs. Ag nanoparticles promote, in alkaline media, a 4e- pathway of the ORR, optimizing the conversion of oxygen into water at the expense of hydrogen peroxide.1 However, the activity of Ag is limited by the strong hydroxide anion (OH-) binding energy, which reduces the free active sites destined to oxygen adsorption.1 To overcome this, Ag electrocatalysts were modified with metal-phthalocyanines (M-Pc M=Co, Fe, Cu) and supported on Ketjen-black carbon and on Ceria/Ketjen black (CeO2/C) supports. The synergistic effect between M-Pc and Ag NPs optimizes the OH- binding energy enhancing the ORR performances.2,3 The employment of ceria, thanks to its high oxophylicity, improves the transfer of OH- to the metal surface.4,5 The dispersion and size of nanoparticles (5-15 nm) was controlled through the Turkevich synthesis method, in order to maximize the interaction between Ag and Me-Pc. Physical characterization has been realized by High Resolution Trasmission Electron Microscopy (HR-TEM), X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) while electrochemical behaviour has been explored in half cells and in complete AEMFCs. References Erikson, H., Sarapuu, A., & Tammeveski, K. (2019). Oxygen reduction reaction on silver catalysts in alkaline media: a minireview. ChemElectroChem, 6(1), 73-86.. Miller, H. A., Bevilacqua, M., Filippi, J., Lavacchi, A., Marchionni, A., Marelli, M., ... & Vizza, F. (2013). Nanostructured Fe–Ag electrocatalysts for the oxygen reduction reaction in alkaline media. Journal of Materials Chemistry A, 1(42), 13337-13347. Miller, H. A., Bellini, M., Oberhauser, W., Deng, X., Chen, H., He, Q., ... & Vizza, F. (2016). Heat treated carbon supported iron (ii) phthalocyanine oxygen reduction catalysts: elucidation of the structure–activity relationship using X-ray absorption spectroscopy. Physical Chemistry Chemical Physics, 18(48), 33142-33151. Miller, H. A., Bellini, M., Dekel, D. R., & Vizza, F. (2022). Recent developments in Pd-CeO2 nano-composite electrocatalysts for anodic reactions in anion exchange membrane fuel cells. Electrochemistry Communications, 135, 107219. Bellini, M., Pagliaro, M. V., Marchionni, A., Filippi, J., Miller, H. A., Bevilacqua, M., ... & Vizza, F. (2021). Hydrogen and chemicals from alcohols through electrochemical reforming by Pd-CeO2/C electrocatalyst. Inorganica Chimica Acta, 518, 120245. Figure 1

Estilos ABNT, Harvard, Vancouver, APA, etc.

46

Chen, Zilong, Wenxia Xu, Weizhou Wang, Zhe Wu, Hongdong Li, Jianping Lai e Lei Wang. "Bamboo‐Like Carbon Nanotube‐Encapsulated Fe₂C Nanoparticles Activate Confined Fe₂O₃ Nanoclusters Via d‐p‐d Orbital Coupling for Alkaline Oxygen Evolution Reaction". Small, 10 de novembro de 2024. http://dx.doi.org/10.1002/smll.202409325.

Texto completo da fonte

Resumo:

AbstractThe efficient anion exchange membrane water electrolysis is challenging with low cell voltage and long‐term stability at large current density, due to the unstable anodic oxygen evolution reaction (OER). Fe‐based electrocatalysts are potential candidates for the anodic OER. In Fe‐based materials, iron oxides always show better stability in alkaline solution but lower OER activity. However, the catalysts in previous study are difficult to continuously and effectively activate iron oxides supported on carbon during electrocatalysis. Herein, a new class of electrocatalyst: bamboo‐like carbon nanotubes (B‐CNT)‐encapsulated Fe2C nanoparticles (NPs) supported Fe2O3 nanoclusters (NCs), named Fe2O3/B‐CNT@Fe2C is reported. Theoretical calculations and experimental results reveal that B‐CNT‐encapsulate Fe2C NPs activate Fe2O3 NCs by the d‐p‐d orbital coupling, thereby weakening the adsorption of OOH* intermediate during OER process. The electrolyzer based on the electrocatalyst requires only 1.48 V to reach 1.0 A cm−2 and shows a long‐term stability at 1.0 A cm−2 for 1600 h, comparable to the best‐reported values for the anion exchange membrane water electrolyzer (AEMWE).

Estilos ABNT, Harvard, Vancouver, APA, etc.

47

Niyati, Ataollah, Arianna Moranda, Juan Felipe Basbus e Ombretta Paladino. "Unlocking the Potential of NiCo2O4 Nanocomposite: Morphology Modification via Urea Quantity, Hydrothermal and Calcination Temperature". New Journal of Chemistry, 2024. http://dx.doi.org/10.1039/d4nj01581a.

Texto completo da fonte

Resumo:

Oxygen Evolution Reaction (OER) electrocatalysts are critical in minimizing energy loss during the anodic four-electron transfer process that is required for water oxidation. Improving and selecting optimal non-nobel OER electrocatalysts...

Estilos ABNT, Harvard, Vancouver, APA, etc.

48

Cai, Linke, Yao Liu, Ying Gao, Bo-Hang Zhao, Jiacheng Guan, Xiao Liu, Bin Zhang e Yi Huang. "Atomically Asymmetrical Ir–O–Co Sites Enable Efficient Chloride‐mediated Ethylene Electrooxidation in Neutral Seawater". Angewandte Chemie, 25 de outubro de 2024. http://dx.doi.org/10.1002/ange.202417092.

Texto completo da fonte

Resumo:

The chloride‐mediated ethylene oxidation reaction (EOR) of ethylene chlorohydrin (ECH) via electrocatalysis is practically attractive because of its sustainability and mild reaction conditions. However, the chlorine oxidation reaction (COR), which is essential for the above process, is commonly catalyzed by dimensionally stable anodes (DSAs) with high contents of precious Ru and/or Ir. The development of highly efficient COR electrocatalysts composed of nonprecious metals or decreased amounts of precious metals is highly desirable. Herein, we report a modified Co3O4 with a single‐atom Ir substitution (Ir1/Co3O4) as a highly efficient COR electrocatalyst for chloride‐mediated EOR to ECH in neutral seawater. Ir1/Co3O4 achieves a Faradaic efficiency (FE) of up to 94.8% for ECH generation and remarkable stability. Combining experimental results and density functional theory (DFT) calculations, the unique atomically asymmetrical Ir‐O‐Co configuration with a strong electron coupling effect in Ir1/Co3O4 can accelerate electron transfer to increase the reaction kinetics and maintain the structural stability of Co3O4 during COR. Moreover, a coupling reaction system integrating the anodic chloride‐mediated and cathodic H2O2‐mediated EOR show a total FE of ~170% for paired electrosynthesis of ECH and ethylene glycol (EG) using ethylene as the raw material. The technoeconomic analysis highlights the promising application prospects of this system.

Estilos ABNT, Harvard, Vancouver, APA, etc.

49

Cai, Linke, Yao Liu, Ying Gao, Bo-Hang Zhao, Jiacheng Guan, Xiao Liu, Bin Zhang e Yi Huang. "Atomically Asymmetrical Ir–O–Co Sites Enable Efficient Chloride‐mediated Ethylene Electrooxidation in Neutral Seawater". Angewandte Chemie International Edition, 25 de outubro de 2024. http://dx.doi.org/10.1002/anie.202417092.

Texto completo da fonte

Resumo:

The chloride‐mediated ethylene oxidation reaction (EOR) of ethylene chlorohydrin (ECH) via electrocatalysis is practically attractive because of its sustainability and mild reaction conditions. However, the chlorine oxidation reaction (COR), which is essential for the above process, is commonly catalyzed by dimensionally stable anodes (DSAs) with high contents of precious Ru and/or Ir. The development of highly efficient COR electrocatalysts composed of nonprecious metals or decreased amounts of precious metals is highly desirable. Herein, we report a modified Co3O4 with a single‐atom Ir substitution (Ir1/Co3O4) as a highly efficient COR electrocatalyst for chloride‐mediated EOR to ECH in neutral seawater. Ir1/Co3O4 achieves a Faradaic efficiency (FE) of up to 94.8% for ECH generation and remarkable stability. Combining experimental results and density functional theory (DFT) calculations, the unique atomically asymmetrical Ir‐O‐Co configuration with a strong electron coupling effect in Ir1/Co3O4 can accelerate electron transfer to increase the reaction kinetics and maintain the structural stability of Co3O4 during COR. Moreover, a coupling reaction system integrating the anodic chloride‐mediated and cathodic H2O2‐mediated EOR show a total FE of ~170% for paired electrosynthesis of ECH and ethylene glycol (EG) using ethylene as the raw material. The technoeconomic analysis highlights the promising application prospects of this system.

Estilos ABNT, Harvard, Vancouver, APA, etc.

50

Wang, Yan, Ming Ni, Wei Yan, Chuhong Zhu, Daochuan Jiang, Yupeng Yuan e Haiwei Du. "Supported High‐Entropy Alloys for Electrooxidation of Benzyl Alcohol Assisted Water Electrolysis". Advanced Functional Materials, 29 de novembro de 2023. http://dx.doi.org/10.1002/adfm.202311611.

Texto completo da fonte

Resumo:

AbstractElectrocatalytic hydrogen production technology is essentially vital for future green and sustainable energy revolution while its large‐scale industrial application is still unsatisfactory due to the low efficiency of electrocatalysts and kinetically sluggish oxygen evolution reaction (OER). Developing novel electrocatalysts and coupling them with upgrading organic molecules are considered effective solutions. Herein, it reports a high‐entropy composite electrocatalyst consisting of FeCoNiAlMo alloy and carbon nanotube (CNT) for anodic benzyl alcohol (BA) electrooxidation coupled with cathodic hydrogen production. Because of the lower charge transfer resistance and faster reaction kinetics, the quinary FeCoNiAlMo/CNT is highly active to OER, remarkably outperforming the ternary FeCoNi/CNT counterpart. Then, the FeCoNiAlMo/CNT composite electrocatalyst is further utilized for BA oxidation reaction‐assisted hydrogen evolution. Combining the experimental and calculation results, the different activities when tested in BA‐containing or BA‐free electrolytes can be attributed to the different metal active sites with specific surface adsorption effects to water and BA molecules, respectively. This work develops a novel electrocatalyst for high‐efficient alcohol oxidation‐assisted electrolysis.

Estilos ABNT, Harvard, Vancouver, APA, etc.

Artigos de revistas sobre o tema "Anodic electrocatalysts"

Crie uma referência precisa em APA, MLA, Chicago, Harvard, e outros estilos