Unveiling the Role of Single Atomic Ruthenium Decorated Cactus-Like Bimetallic Phosphides for Alkaline Water Electrolysis

Abstract

High-performance water-splitting electrocatalysts are pivotal for green hydrogen production. The bimetallic phosphide (NiCoP), as a promising candidate for alkaline water electrolysis, still faces challenges including sluggish reaction kinetics and instability. Herein, Ru single atoms (SAs) are anchored on cactus-like NiCoP-coated Ni foam (Ru SAs@NiCoP/NF) as a robust bifunctional catalyst for alkaline water electrolysis. Atomic dispersion of Ru via P-rich coordination induces electron redistribution, optimizing d-band centers of Ni/Co sites to reduce energy barriers for water dissociation and O₂ desorption. For the hydrogen evolution reaction (HER), Ru synergistically enhances water activation and optimizes the HER process, yielding ultralow overpotentials of 8 and 240 mV at current densities of 10 and 500 mA cm⁻². For the oxygen evolution reaction (OER), Ru promotes phosphorus leaching and surface reconstruction, adjusting the adsorption–desorption of intermediates in the lattice oxygen mechanism, achieving 375 mV overpotential at 1.0 A cm⁻². Remarkably, the anion exchange membrane water electrolyzer using the Ru SAs@NiCoP/NF bifunctional catalysts carries only a cell voltage of 1.76 V at 0.5 A cm⁻² at 80 °C for overall water splitting and long-term stability. This work reveals the critical role of single atom-supports synergy in optimizing the electronic structure and enhancing the electrocatalytic performances for high-current-density water electrolysis catalysts.