Modulating the electronic structure of cobalt sites by zinc to promote the oxygen evolution electrocatalysis

Abstract

Cobalt-based catalysts have shown activity in the oxygen evolution reaction (OER) under alkaline conditions, yet enhancing the intrinsic performance of CoOx sites remains challenging. Herein, Zn was uniformly incorporated into the structure of Co layered (oxy)hydroxides via a structural reconstruction process, resulting in a configuration where Zn is distributed in the vicinity of CoOx sites. X-ray photoelectron spectroscopy analysis reveals that the presence of Zn increases the oxidation state of Co and modulates the electronic structure of Co coordination centers through regulation of the oxygen species. In situ electrochemical infrared spectroscopy and theoretical calculations demonstrate that the introduction of Zn facilitates the transformation of *OH to *O and promotes the formation of *OOH intermediates. Further electronic structure analysis indicates that Zn regulates the electron population and spin state within the CoO5/6 coordination units. Specifically, by forming a bridged Zn–O–Co motif, Zn promotes the stabilization of high-valence Co in a higher spin state, favoring the formation of Co–oxo species and thereby enhancing the OER performance of the CoOx sites.