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机构地区:[1]中国科学技术大学合肥微尺度物质科学国家实验室(筹),化学物理系,合肥230026
出 处:《Chinese Journal of Chemical Physics》2014年第1期63-68,I0003,I0004,共8页化学物理学报(英文)
基 金:ACKNOWLEDGMENTS This work was supported by the One Hundred Talents' Program of the Chinese Academy of Science, the National Natural Science Foundation of China (No.21073176), and the National Basic Research Program of China National Science and Technology (No.2010CB923302).
摘 要:Hydrogen evolution reaction (HER) at polycrystalline silver electrode in 0.1 mol/L HClO4 solution is investigated by cyclic voltammetry in the temperature range of 278-333 K. We found that at electrode potential φa,app decreases with φ, while pre-exponential factor A remains nearly unchanged,which conforms well the prediction from Butler-Volmer equation. In contrast, with φ nega-tive shifts from the onset potential for HER to the potential of zero charge (PZC≈-0.4 V), both Ea,app and A for HER increase (e.g., Ea,app increases from 24 kJ/mol to 32 kJ/mol). The increase in Ea,app and A with negative shift in φ from -0.25 V to PZC is explained by the increases of both internal energy change and entropy change from reactants to the transition states, which is correlated with the change in the hydrogen bond network during HER. The positive entropy effects overcompensate the adverse effect from the increase in the activation energy, which leads to a net increase in HER current with the activation energy negative shift from the onset potential of HER to PZC. It is pointed out that entropy change may contribute greatly to the kinetics for electrode reaction which involves the transfer of electron and proton, such as HER.
关 键 词:Hydrogen evolution reaction Ag electrode Temperature effect Activation energy Pre-exponential factor Internal energy Entropy change
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