Self-Supported FeNiP Nanosheet Arrays as a Robust Bifunctional Electrocatalyst for Water Splitting

Bimetallic FeNiP nanosheet arrays on a nickel foam (FeNiP@NFO) are fabricated by an in situ oxidative etching process coupled with phosphorization. The self-supported FeNiP@NFO catalyst exhibits prominent catalytic activity for a hydrogen evolution reaction with overpotentials as low as 64, 82, and 54 mV at 10 mA·cm–2 in 1.0 M PBS, 1.0 M KOH, and 0.5 M H2SO4, respectively, surpassing most reported non-noble catalysts. Moreover, FeNiP@NFO requires an overpotential of 193 mV in 1.0 M KOH to drive 10 mA·cm–2 for an oxygen evolution reaction. The overall water-splitting electrolyzer assembled with FeNiP@NFO as both the anodic and cathodic electrodes exhibits an extremely low cell voltage of 1.49 V to achieve a current density of 10 mA·cm–2, which is much lower than that of most alkaline electrolysis systems. The extraordinary electrocatalytic activity of FeNiP@NFO is ascribed to the synergistic effect between elements and the special network compiled by nanosheet arrays, which offers high conductivity, abundant accessible active sites, easy hydrogen release channels, and fast electron transportation.