Unifying the Hydrogen Evolution and Oxidation Reactions Kinetics in Base by Identifying the Catalytic Roles of Hydroxyl-Water-Cation Adducts

TitleUnifying the Hydrogen Evolution and Oxidation Reactions Kinetics in Base by Identifying the Catalytic Roles of Hydroxyl-Water-Cation Adducts
Publication TypeJournal Article
Year of Publication2019
AuthorsLiu E, Li J, Jiao L, Doan HThi Thanh, Liu Z, Zhao Z, Huang Y, Abraham K.M, Mukerjee S, Jia Q
JournalJournal of the American Chemical Society
Volume141
Issue7
Pagination3232-3239
Date Published02/2019
ISSN0002-7863
Abstract

Published on February 20th, 2019. Despite the fundamental and practical significance of the hydrogen evolution and oxidation reactions (HER/HOR), their kinetics in base remain unclear. Herein, we show that the alkaline HER/HOR kinetics can be unified by the catalytic roles of the adsorbed hydroxyl (OHad)-water-alkali metal cation (AM+) adducts, on the basis of the observations that enriching the OHad abundance via surface Ni benefits the HER/HOR; increasing the AM+ concentration only promotes the HER, while varying the identity of AM+ affects both HER/HOR. The presence of OHad-(H2O)x-AM+ in the double-layer region facilitates the OHad removal into the bulk, forming OH–-(H2O)x-AM+ as per the hard–soft acid–base theory, thereby selectively promoting the HER. It can be detrimental to the HOR as per the bifunctional mechanism, as the AM+ destabilizes the OHad, which is further supported by the CO oxidation results. This new notion may be important for alkaline electrochemistry.

URLhttps://doi.org/10.1021/jacs.8b13228
DOI10.1021/jacs.8b13228