Trimetallic oxyhydroxides as active sites for large-current-density alkaline oxygen evolution and overall water splitting

Earth-abundant electrocatalysts for large-current-density water splitting under alkaline condition are desirable.Oxygen evolution reaction,which is a bottleneck of the overall water splitting,faces the problems of complicated reconstruction and deficiency in rational design of active sites.Herein,we report a series of transition metal chalcogenides for alkaline OER.Among them,FeCoNi(S)displayed a low overpotential of 293 m V to deliver a current density of 500 m A cm^(-2),which is in the top level of non-precious metal based OER electrocatalysts.A combination of(ex)in situ characterizations and DFT calculation shows that Ni(Fe,Co)trimetallic oxyhydroxides were the active sites for highly-efficient OER.Furthermore,for FeCoNi(S),when used as a bifunctional catalyst for water splitting,it only required a cell voltage of 1.84 V to deliver~500 m A cm^(-2) with extraordinary long-term stability over 2000 h.This work provides the comprehension of high-efficiency,robust catalysts for OER and overall water splitting at large current densities in alkaline media.