Activating Inert ZnO by Surface Cobalt Doping for Efficient Water Oxidation in Neutral Media

Abstract

Precisely modulating the electronic structure of catalytic sites represents a promising strategy to design highly efficient electrocatalysts toward oxygen evolution reaction (OER). Here, the non-noble metal Co is successfully doped into the surface layer of ZnO and the doping concentration can be controllably adjusted by a partial cation exchange method. Our experimental and theoretical results demonstrate that the surface-doped Co can not only activate the inherently inert Zn sites by modifying their electronic structure and thereby promoting the OH* adsorption but also serve as active sites themselves for the adsorption of O* and OOH*, ultimately realizing the bimetallic synergetic effect in Co/ZnO for OER catalysis. Besides, the surface Co doping also benefits the obvious enhancement of electrical conductivity of the ZnO host. Therefore, relative to the inactive ZnO, the as-prepared Co/ZnO exhibits a much smaller overpotential and Tafel slope toward OER. This strategy provides a rational design of low-cost and efficient OER electrocatalysts.