Activation of transition metal oxides by in-situ electro-regulated structure-reconstruction for ultra-efficient oxygen evolution

Cobalt oxides with abundant defects, including those with fully exposed active sites and abundant oxygen vacancies, exhibit superb catalytic activities towards oxygen evolution reaction (OER). Herein, we report a facile in-situ electrochemical self-optimization strategy to produce carbon-fiber-supported defective CoO x (E-CoO x /CF), in which the partial self-dissolution of acidic oxides under alkaline OER operational conditions and releasing of in-situ generated oxygen molecules are taken as advantages for reconstruction of Co species with abundant defects, Co 2+ and oxygen vacancies. The resultant E-CoO x /CF can achieve 10 mA cm −2 at a low overpotential of 249 mV with a remarkable stability (>100 h without performance decay). Moreover, this electrochemical etching method can also be extended to the preparation of highly active transition metal nickel oxides for enhanced OER. This study represents a new yet efficient strategy for rationally designing and developing advanced transition metal oxides for various electrochemical applications and beyond.