Understanding hydrogen electrocatalysis by probing the hydrogen-bond network of water at the electrified Pt/solution interface
A grand challenge in electrochemistry is to understand and promote electrochemical processes by exploring and exploiting the interface. Herein, we promoted the hydrogen evolution and oxidation reactions (HER/HOR) of platinum in base by employing N-methylimidazoles to reorientate interfacial water against the interfacial electric field as evidenced by in situ spectroscopic characterization of the interface. We accordingly established a unified mechanism by which the HER/HOR in acid and base proceeds via diffusion of proton and hydroxide, respectively, through interface via interfacial water by the Grotthuss mechanism. This mechanism accounts for the pH-dependent HER/HOR kinetics of platinum, a long-standing puzzle. Furthermore, we demonstrated 40% performance improvement of an anion exchange membrane electrolyzer by adding 1,2-dimethylimidazole into the alkaline solution fed into its Pt cathode.
CC BY NC ND 4.0 License. This work was supported by the Office of Naval Research (ONR) grant N000141712608 (Q.J.) This research used beamline 7-BM (QAS) of the National Synchrotron Light Source II, a U.S. Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Brookhaven National Laboratory Contract DE-SC0012704. Beamline operations were supported in part by the Synchrotron Catalysis Consortium Grant DE-SC0012335. W.A.G. acknowledges support by the Liquid Sunlight Alliance, which is supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, Fuels from Sunlight Hub under Award Number DE-SC0021266.; This work used the Extreme Science and Engineering Discovery Environment (XSEDE) for AIMD simulation, which is supported by the NSF grant number ACI-1548562. S.K. acknowledges support from the Resnick Sustainability Institute at Caltech.
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