Ultra-stable trimetallic phosphide heterostructure with regulated electronic structure for overall water splitting at high current densities

Developing ultra-stable electrocatalysts for highly efficient overall water splitting at high current density (HCD) is critical for renewable hydrogen/oxygen production in the industry. However, the most active electrocatalysts for large current-driven water splitting are seriously handicapped by insufficient electrical contact kinetics due to the intensive bubble overflow. Herein, we demonstrate the ultra-stable trimetallic phosphides of NiFeP/NiCoP catalysts on a hydrophilic Ni foam skeleton via a corrosion-hydrothermal-phosphating strategy. The optimized NiFeP/NiCoP catalyst stabilizes for 600 h at −1 A cm −2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) in alkaline solution, and it only needs low overpotentials of 237 and 314 mV to drive HER and OER at 1 A cm −2 , respectively. As expected, the optimized NiFeP/NiCoP electrode maintains 1000 h at 0.5 A cm −2 for water splitting, ranking among the top performers among reported catalysts. Such excellent performance could be attributed to the fast electron transfer for electrochemical reactions , the electron-deficient Fe/Ni sites contribute to forming robust metal oxyhydroxide during OER, and electron-rich Co sites facilitate H adsorption during HER. The findings present a highly promising candidate for ultra-stable non-noble metal electrocatalysts , offering a viable option for hydrogen/oxygen supply for fuel cells and metal-air batteries . The composition-balanced NiFeP/NiCoP electrodes stabilize for HER and OER over 600 h with a current density up to 1 A cm −2 . The electron-deficient Fe/Ni and electron-rich Co sites contribute to achieving this remarkable catalytic stability. The NiFeP/NiCoP-10 (+) || NiFeP/NiCoP-10 (−) electrode pairs present recorded stability with a long-lasting period of 1000 h at 0.5 A cm −2 for driving water splitting. • Corrosion-hydrothermal-phosphating yields NiFeP/NiCoP catalysts on Ni foam. • Optimized NiFeP/NiCoP endures 1000 h of water splitting at 0.5A cm −2 . • Trimetallic NiFeP/NiCoP displays fast electron transfer capability. • High-valence Ni/Fe sites in NiFeP/NiCoP boost the surface reconstruction for OER. • Low-valence states of Co sites in NiFeP/NiCoP favor H adsorption for HER.