Department of Chemistry and Chemical Biology , Northeastern University , Boston , Massachusetts 02115 , United States.
Department of Chemical Engineering , Northeastern University , Boston , Massachusetts 02115 , United States.
J Am Chem Soc. 2019 Feb 20;141(7):3232-3239. doi: 10.1021/jacs.8b13228. Epub 2019 Feb 6.
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 (OH)-water-alkali metal cation (AM) adducts, on the basis of the observations that enriching the OH 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 OH-(HO) -AM in the double-layer region facilitates the OH removal into the bulk, forming OH-(HO) -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 OH, which is further supported by the CO oxidation results. This new notion may be important for alkaline electrochemistry.
尽管氢的析出和氧化反应（HER/HOR）具有基础和实际意义，但它们在碱性条件下的动力学仍不清楚。在此，我们基于表面 Ni 富集会增加 OH 含量从而有利于 HER/HOR 的观察结果，提出通过吸附的羟基（OH）-水-碱金属阳离子（AM）加合物的催化作用，可统一碱性 HER/HOR 的动力学。增加 AM 浓度仅促进 HER，而改变 AM 的种类则同时影响 HER/HOR。双层区域中存在 OH-(HO)-AM 有助于 OH-进入本体，根据软硬酸碱理论形成 OH-(HO)-AM，从而选择性地促进 HER。根据双功能机理，这对 HOR 不利，因为 AM 会使 OH 不稳定，这一观点进一步得到了 CO 氧化结果的支持。这一新概念可能对碱性电化学很重要。
