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

Exploring cost-effective and high-performance electrocatalysts for oxygen evolution reaction (OER) is quite significant for utilizing renewable energies by converting them to green hydrogen energy. ZnCo2O4 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 ZnCo2O4 catalyst. Herein, a facile, easy-scalable and environmental-friendly quenching method is exhibited to achieve surface Fe doped and oxygen vacancy generated ZnCo2O4 by instantaneous cooling in Fe(NO3)3 solution. As a result, the quenched ZnCo2O4 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 ZnCo2O4 (405 mV). Our results manifest that quenching treatment can endow an active Fe amorphous layer, a higher ratio of Co3+ states and more abundance oxygen vacancies for ZnCo2O4 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.

Automated summary

Exploring cost-effective and high-performance electrocatalysts for the oxygen evolution reaction (OER) is important for utilizing renewable energies. The quenching method introduced in this work successfully enhances the OER activity of ZnCo2O4 catalyst by generating Fe doped and oxygen vacancy. The quenched ZnCo2O4 catalyst exhibits vastly improved OER activity compared to the un-quenched counterpart.