Template Synthesis of Amorphous NiFeCuO x Arrays for Efficient Anion-Exchange Membrane Water Oxidation

Abstract

Hydrogen production via anion-exchange membrane (AEM) water electrolyzer has emerged as one of the most promising strategies for large-scale hydrogen generation, owing to its low cost, rapid response, and modular scalability. However, the oxygen evolution reaction (OER) at the anode is still suffering from intrinsically sluggish four-electron-transfer kinetics, which remains a critical bottleneck to commercialization. In this work, we synthesized an amorphous NiFe-based hierarchical array OER catalyst using a template-assisted method. This hierarchical array promotes rapid electron transport and exposes abundant active sites, exhibiting an overpotential of 283 mV to achieve a current density of 100 mA cm -2 and stable operation for more than 100 h. Furthermore, in situ electrochemical Raman spectroscopy revealed the structural transformation of Ni active sites during OER. The AEM water electrolyzer assembled with the NiFeCuOx array catalysts delivers an industrial-level current density of 2.7 A cm -2 at 2.0 Vcell. This template-assisted synthesis method provides a new pathway for constructing NiFe-based OER catalysts and also offers valuable insights for advancing the commercial implementation of AEM electrolysis technology.