Quenching-induced surface engineering of ZnCo2O4 spinel oxide for enhanced oxygen evolution reaction

• ZnCo 2 O 4 nanoparticles with Fe surface doped is achieved by quenching treatment. • Quenching endows the ZnCo 2 O 4 electrocatalyst with an active Fe amorphous layer, a higher ratio of Co 3+ states and more abundance oxygen vacancies. • The ZnCo2O4-0.01Fe electrocatalyst presents an enhanced OER activities. • This work paves an new route for the surface regulation of metal oxides and its application in the field of energy storage and conversion. Exploring cost-effective and high-performance electrocatalyst for oxygen evolution reaction (OER) is quite significant for utilizing renewable energies by converting them to green hydrogen energy. ZnCo 2 O 4 spinel oxide has drawn a wide attention in water electrolysis field owing to its earth abundance, low cost and eminent electrocatalytic activity. However, it still has a great room to boost its OER catalytic activity due to the low electrical conductivity and restricted active sites of ZnCo 2 O 4 catalyst. Herein, a facile, easy-scalable and environmental-friendly quenching method is exhibited to achieve surface Fe doped and oxygen vacancy generated ZnCo 2 O 4 by instantaneous cooling in Fe(NO 3 ) 3 solution. As a result, the quenched ZnCo 2 O 4 catalyst shows a vastly improved OER activity in alkaline electrolyte, only requiring an overpotential of 332 mV to reach 10 mA cm -2 , which is much lower than that of un-quenched ZnCo 2 O 4 (405 mV). Our results manifest that quenching treatment can endow an active Fe amorphous layer, a higher ratio of Co 3+ states and more abundance oxygen vacancies for ZnCo 2 O 4 spinel oxide, thus possessing a higher OER activity. Our work offers an effective path for the regulation of metal oxides and its application in energy catalysis field.