Efficient oxygen evolution on spinel MFe2O4 (M=Zn and Ni) electrocatalysts

Abstract Electrochemical water splitting for the oxygen evolution reaction (OER) requires highly active, long-durable and cost-effective catalysts to meet the needs of large-scale hydrogen production in the future. Herein, we studied the OER performance of spinel MFe 2 O 4 (M=Zn and Ni) and NiO x . These metal oxides showed markedly different activities, which were closely related to their charge-transfer resistance and electrochemical surface area, attributing to the amount of oxygen vacancies. Particularly, ZnFe 2 O 4 exhibits superior OER activity with an overpotential of 318 mV at the current density of 10 mA cm -2 (η 10 ) and a Tafel slope of 50 mV dec −1 . Furthermore, ZnFe 2 O 4 also presents outstanding long-term stability for 100 h with negligible decay even at a high current density of 800 mA cm -2 . This work provides a fundamental insights into the oxygen vacancy and spinel structure to help for the design of OER catalyst toward highly efficient water splitting.