A NiCo2O4 electrocatalyst with a thin graphitic coating for the anion exchange membrane water electrolysis of wastewater

Abstract

The production of hydrogen via water electrolysis using renewable energy is key to the development of a sustainable society. However, most current electrocatalysts are based on expensive precious metals and require the use of highly purified water in the electrolyte. We demonstrate a simple preparation of a non-precious metal catalyst based on NiCo₂O₄ (NCO). Further, we used high-energy ball milling with graphite to modify the NCO catalyst to prepare a material with a small particle size, high surface area and high conductivity, which enhanced the electrocatalytic performance of the materials in electrochemical tests and when applied to an anion exchange membrane water electrolyzer. Notably, comparison of the performance of the pristine NCO catalyst and that modified with graphite (NCO@C) revealed that the latter showed better activity and durability for the hydrogen and oxygen evolution reactions under alkaline conditions. Further, we applied the possibility of using this electrocatalyst in alkaline wastewater and observed similar performance and durability to that in pure electrolyte.