Molecular Precursor Route to CuCo2S4 Nanosheets: A High-Performance Pre-Catalyst for Oxygen Evolution and Its Application in Zn-Air Batteries.

Development of high-efficiency non-precious metal-based electrocatalysts to drive the complex four-electron process of the oxygen evolution reaction (OER) is crucial for production of hydrogen and energy storage components. Herein, bimetallic CuCo2S4 nanosheets were created by a new molecular precursor route. The optimal CuCo2S4 catalyst demonstrates superior performance to catalyze the OER with excellent stability, which was confirmed by the low overpotential of 290 mV at 10 mA cm-2 in 1 M KOH. The catalytic activity can be maintained for at least 40 h. The catalyst after the OER was then detected. The results indicate that S-doped CoOOH/CuO nanosheets formed on the catalyst surface during the OER may act as the catalytic active substance. Furthermore, when employed as an air cathode in a Zn-air battery, it reveals a high open-cycle potential of 1.38 V and a peak power density of 123.9 mW cm-2. The performance of the rechargeable Zn-air battery is close to that fabricated with commercial precious metal-based electrocatalysts. These findings would furnish some guidelines for the design, development, and applications of bimetallic sulfide electrocatalysts for the OER.