Mechanism of Cations Suppressing Proton Diffusion Kinetics for Electrocatalysis |
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| Authors: | Xiao-Yu Li Dr Tao Wang Yu-Chen Cai Zhao-Dong Meng Jing-Wen Nan Dr Jin-Yu Ye Prof Dr Jun Yi Prof Dr Dong-Ping Zhan Prof Dr Na Tian Prof Dr Zhi-You Zhou Prof Dr Shi-Gang Sun |
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| Institution: | 1. State Key Laboratory of Physical Chemistry of Solid Surfaces, Tan Kah Kee Innovation Laboratory, Collaborative Innovation Center of Chemistry for Energy Materials, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, 361005 P. R. China;2. School of Electronic Science and Engineering, Xiamen University, Xiamen, 361005 P. R. China |
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| Abstract: | Proton transfer is crucial for electrocatalysis. Accumulating cations at electrochemical interfaces can alter the proton transfer rate and then tune electrocatalytic performance. However, the mechanism for regulating proton transfer remains ambiguous. Here, we quantify the cation effect on proton diffusion in solution by hydrogen evolution on microelectrodes, revealing the rate can be suppressed by more than 10 times. Different from the prevalent opinions that proton transport is slowed down by modified electric field, we found water structure imposes a more evident effect on kinetics. FTIR test and path integral molecular dynamics simulation indicate that proton prefers to wander within the hydration shell of cations rather than to hop rapidly along water wires. Low connectivity of water networks disrupted by cations corrupts the fast-moving path in bulk water. This study highlights the promising way for regulating proton kinetics via a modified water structure. |
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| Keywords: | Cation Effect Electrocatalysis Proton Diffusion Kinetics Water Structure |
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