Nonprecious bimetallic NiFe-layered hydroxide nanosheets as a catalyst for highly efficient electrochemical water splitting

Abstract

It has become highly necessary to advance stable, cost-effective, and energy-efficient hydrogen production using non-precious metal-based water electrolysis to replace the increasing demand for fossil fuels and maintain environmental safety. Herein, we present the synthesis of non-precious bimetallic Ni1-xFex-layered hydroxide nanosheet films by using a chemical-bath deposition technique for use as oxygen evolution reaction (OER) catalysts for electrochemical water electrolysis. Remarkably, the optimized Ni0.50Fe0.50-layered hydroxide electrode exhibited excellent OER activity in 1 M potassium hydroxide electrolyte while having a low overpotential of 239.7 mV at a current density of 10 mA cm(-2) with a small Tafel slope of 38.02 mV dec(-1). It was electrochemically stable over 100 hours of continuous OER operation, thereby showing its excellent electrochemical stability. The results from a post-OER study reveal that catalytically active OER sites are associated with the formation of a nickel oxyhydroxide intermediate on the surface of the electrode. The maximum synergy among good electronic conductivity, high diffusion coefficient, and enlarged electrochemically active sites was obtained by optimizing the Ni/Fe ratio and thereby, the OER activity.