Synthesis and evaluation of bifunctional electrocatalytic activity of NiCoP nanosheets for overall water splitting

Abstract

Low-cost transition-metal-based electrocatalysts are promising alternatives to Pt-, Ir-, and Ru-based catalysts for water electrolysis owing to their lower cost and greater abundance. However, the development of bifunctional electrocatalysts capable of efficiently catalysing both the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER) remains a significant challenge. Herein, this study reports an effective strategy for synthesising NiCoP nanosheets directly on three-dimensional Ni foam (NiCoP/NF) as a bifunctional electrocatalyst for overall water splitting in alkaline media. The successful formation of the NiCoP/NF nanosheet structure was confirmed by SEM and XRD analyses. In 1.0 M KOH, the as-prepared NiCoP/NF electrode exhibited high catalytic activity toward both HER and OER, requiring overpotentials of 89 and 350 mV versus RHE, respectively, to achieve current densities of 10 and 50 mA cm^-². The electrode also demonstrated high operational stability for both reactions. Remarkably, when NiCoP/NF was employed as a bifunctional catalyst for overall water splitting, the electrolyser required a low cell voltage of only 1.54 V to reach 10 mA cm^-² while maintaining high long-term stability. These results highlight NiCoP/NF as a promising electrocatalyst for efficient and low-cost alkaline water electrolysis.