Interfacial engineering of nickel/iron/ruthenium phosphides for efficient overall water splitting powered by solar energy

Abstract

Exploiting high-performance, low-cost, and robust bifunctional catalysts toward electrochemical water splitting is of great importance, but remains challenging. Herein, a novel hybrid electrocatalyst of Ni–Fe–Ru-based phosphide heterostructures directly grown on nickel foam (Ni₂P–Fe₂P–Ru₂P/NF) is synthesized by a simple two-step strategy. When assessed as a bifunctional catalyst toward the oxygen evolution reaction (OER) and hydrogen evolution reaction (HER), the resultant Ni₂P–Fe₂P–Ru₂P/NF electrode shows remarkable electrocatalytic performance and long-time durability in alkaline electrolytes due to the collaborative contributions of abundant heterointerfaces, good conductivity, and 3D porous architecture. As expected, to afford a current density of 10 mA cm⁻², the as-prepared Ni₂P–Fe₂P–Ru₂P/NF merely requires low overpotentials of 195 and 78.6 mV for the OER and HER, respectively, comparable to most bifunctional electrocatalysts reported to date. The Ni₂P–Fe₂P–Ru₂P/NF//Ni₂P–Fe₂P–Ru₂P/NF electrolyzer demonstrates a low voltage of 1.49 V for 10 mA cm⁻² along with excellent stability, exceeding that of Pt–C/NF//IrO₂/NF (1.64 V). Furthermore, the H₂ generation driven by commercial solar cells is evaluated to stimulate practical applications in the future.