Nickel–manganese bimetallic phosphides porous nanosheet arrays as highly active bifunctional hydrogen and oxygen evolution electrocatalysts for overall water splitting

Abstract

The development of active, stable, and cost-effective overall water splitting catalysts consisting of earth-abundant materials is of paramount importance for renewable energy production. Herein, we demonstrate the synthesis of bimetallic nickel manganese phosphide porous nanosheet arrays (PNAs) grown on 3D Ni foam (Ni–Mn–P PNAs). Benefiting from the typical 3D PNAs structure and electronic interaction between Ni and Mn, the optimal Ni2Mn1P PNAs shows small overpotentials of 80 and 120 mV to reach 10 mA cm−2 for hydrogen evolution reaction in acidic and alkaline media, respectively. The Ni–Mn–P PNAs also shows a high activity toward oxygen evolution reaction in the alkaline media with a low overpotential of 250 mV to drive 20 mA cm−2. The Ni–Mn–P PNAs-based overall water splitting can achieve a current density of 10 mA cm−2 at a low cell voltage of 1.6 V and excellent durability in alkaline solution, outperforming the benchmark Ir/C||Pt/C electrolyzer. This work highlights the formation of Mn-containing ternary metal phosphides PNAs structure as highly active and stable bifunctional electrocatalysts for overall water splitting.