Sulfidation of CoCuO_x Supported on Nickel Foam to Form a Heterostructure and Oxygen Vacancies for a High-Performance Anion-Exchange Membrane Water Electrolyzer

Anion-exchange membrane water electrolyzer (AEMWE) is attracting attention for hydrogen production owing to its ability to employ nonprecious metal catalysts and high energy conversion efficiency. Spinel-structured transition metal oxides exhibit excellent potential in oxygen evolution reaction (OERs). Nevertheless, the research on highly active and durable spinel-structured electrodes for the anodic OER of AEMWE is deficient. Herein, a self-supported S-CoCu oxide/nickel foam (S-CoCuO x /NF) anode was synthesized through a two-step method (electrodeposition and sulfidation). The formation of abundant oxygen vacancies and heterostructure collaboratively enhances the electron and mass transfer, resulting in an overpotential of 313 mV at 100 mA cm –2 for OER. For the lab-scale AEMWE system with the S-CoCuO x /NF anode, a current density of 1 A cm –2 was obtained at 1.87 V (cell voltage) with high durability for 110 h (1 A cm –2 ) at 60 °C. The results will provide insights into developing the spinel structure-derived anode for high-performance AEMWE.