{"title":"Hydrogen Peroxide Generation and Hydrogen Oxidation Reaction on Pt/Co/Pt(111) and Pt/Co/Pt(100) Single-Crystal Model Catalyst Surface","authors":"Kenta Hayashi, Takeru Tomimori, Yoshihiro Chida, Naoto Todoroki, Toshimasa Wadayama","doi":"10.1021/acscatal.4c03106","DOIUrl":null,"url":null,"abstract":"To mitigate proton-exchange membrane (PEM) degradation, suppressing hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) generation is desired for the anode catalyst of PEM fuel cells (PEMFCs), while keeping the hydrogen oxidation reaction (HOR) activity. In this study, Pt/Co/Pt(111) and Pt/Co/Pt(100), approximately 2 nm-thick epitaxially stacked layers of Pt and Pt–Co alloy deposited on Pt(111) and Pt(100) single-crystal surfaces, respectively, were used as microstructural surface models of the Pt–Co anode catalyst, and the H<sub>2</sub>O<sub>2</sub> generation and HOR mechanisms were discussed using the substrate generation/tip collection and tip generation/substrate collection modes of a scanning electrochemical microscope. We found that H<sub>2</sub>O<sub>2</sub> generation on Pt/Co/Pt(111) was much lower than that on clean Pt(111), whereas the H<sub>2</sub>O<sub>2</sub> generation property of Pt/Co/Pt(100) was similar to that of clean Pt(100). The influence of the underlying Co (Pt–Co) layers on H<sub>2</sub>O<sub>2</sub> generation is discussed from the viewpoints of two previously proposed mechanisms: the adsorbed hydrogen (H<sub>ads</sub>)-related and water-adlayer-related mechanisms. Considering the applied potential dependence of H<sub>2</sub>O<sub>2</sub> generation, the former H<sub>ads</sub>-related mechanism could not explain the H<sub>2</sub>O<sub>2</sub> generation behavior of Pt/Co/Pt(100), whereas the latter water-adlayer-related mechanism could apply to both Pt/Co/Pt(111) and Pt/Co/Pt(100). Regarding the HOR, Pt/Co/Pt(100) showed a higher activity than that of clean Pt(100), whereas the activity of Pt/Co/Pt(111) was lower than that of the corresponding clean Pt(111). Such surface-atomic-arrangement-dependent HOR activities of Pt induced by the underlaid Co (Pt–Co) layers can be explained by weakened hydrogen adsorption energy, which can be rationalized by cyclic voltammogram features. The results clarify the alloying effect of Pt with Co for suppressing H<sub>2</sub>O<sub>2</sub> generation while maintaining substantial HOR activity.","PeriodicalId":9,"journal":{"name":"ACS Catalysis ","volume":null,"pages":null},"PeriodicalIF":11.3000,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"ACS Catalysis ","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1021/acscatal.4c03106","RegionNum":1,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
Abstract
To mitigate proton-exchange membrane (PEM) degradation, suppressing hydrogen peroxide (H2O2) generation is desired for the anode catalyst of PEM fuel cells (PEMFCs), while keeping the hydrogen oxidation reaction (HOR) activity. In this study, Pt/Co/Pt(111) and Pt/Co/Pt(100), approximately 2 nm-thick epitaxially stacked layers of Pt and Pt–Co alloy deposited on Pt(111) and Pt(100) single-crystal surfaces, respectively, were used as microstructural surface models of the Pt–Co anode catalyst, and the H2O2 generation and HOR mechanisms were discussed using the substrate generation/tip collection and tip generation/substrate collection modes of a scanning electrochemical microscope. We found that H2O2 generation on Pt/Co/Pt(111) was much lower than that on clean Pt(111), whereas the H2O2 generation property of Pt/Co/Pt(100) was similar to that of clean Pt(100). The influence of the underlying Co (Pt–Co) layers on H2O2 generation is discussed from the viewpoints of two previously proposed mechanisms: the adsorbed hydrogen (Hads)-related and water-adlayer-related mechanisms. Considering the applied potential dependence of H2O2 generation, the former Hads-related mechanism could not explain the H2O2 generation behavior of Pt/Co/Pt(100), whereas the latter water-adlayer-related mechanism could apply to both Pt/Co/Pt(111) and Pt/Co/Pt(100). Regarding the HOR, Pt/Co/Pt(100) showed a higher activity than that of clean Pt(100), whereas the activity of Pt/Co/Pt(111) was lower than that of the corresponding clean Pt(111). Such surface-atomic-arrangement-dependent HOR activities of Pt induced by the underlaid Co (Pt–Co) layers can be explained by weakened hydrogen adsorption energy, which can be rationalized by cyclic voltammogram features. The results clarify the alloying effect of Pt with Co for suppressing H2O2 generation while maintaining substantial HOR activity.
期刊介绍：
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.
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