Hierarchical MoP/Ni2P heterostructures on nickel foam for efficient water splitting

Abstract

Water electrolysis has been considered as one of the most effective, secure and sustainable ways to produce clean hydrogen energy to resolve the looming energy and environmental crisis. Exploring bifunctional catalysts for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) with high efficiency, low cost, and easy integration is crucial for future renewable energy systems. Herein, we report the in situ controllable synthesis of hierarchical MoP/Ni₂P heterostructures on 3D Ni foam (MoP/Ni₂P/NF) and their application as an efficient bifunctional electrocatalyst for water splitting. The hierarchical heterostructures are achieved by a facile hydrothermal approach to obtain the Mo-based/NF precursor, followed by a subsequent in situ phosphorization procedure. Through manipulating the concentration of ammonium molybdate for the preparation of the precursor as well as the phosphorization temperature, the optimal MoP/Ni₂P/NF can be achieved which can efficiently catalyze both the OER and HER in alkaline electrolytes. The superior performance with robust durability is mainly attributed to unique hierarchical heterostructures and collaborative advantages of bimetallic phosphides, as well as the 3D porous conductive substrate. As an integrated high-performance non-noble electrocatalyst for overall water splitting, the MoP/Ni₂P/NF electrode requires a cell voltage of only 1.55 V to achieve a current density of 10 mA cm⁻² in alkaline solution. This work highlights the importance of the design and construction of hierarchical heterostructures for efficient overall water splitting.