Stabilizing the oxygen vacancies and promoting water-oxidation kinetics in cobalt oxides by lower valence-state doping

Introducing oxygen vacancy (Vo) has been regarding as a significant and effective strategy to promote the sluggish oxygen evolution reaction (OER). However, it is a big challenge to stabilize Vo to reserve the excellent activity under the highly oxidizing conditions of the OER process. Herein, we propose a strategy of lower valence-state doping to stabilize the Vo by inducing formation Vo. First-principle calculations indicated that the formation energies of Vo on CoOOH is decreased apparently after lower valence-state Zn doping. The increased holes sates in the t2g orbital can facilitate bonding with oxygen intermediates to activate the inert catalytic activity of CoOOH. Importantly, short hydrogen bonds (O┉H–Oad) are formed by distorting the CoO6 octahedron after Zn-doping, thereby, the formative unique dual-center catalytic pathway can facilitating proton transfer to promote the sluggish OER. Our experimental results confirmed that Zn doped CoOOH contain more Vo, causing excellent durability and fast kinetic process for oxygen evolution including an incremental turnover frequency and a lower Tafel slope. Thus, the lower valence-state doping is promising strategy for fast-stabilized electrocatalytic water oxidation.