Electrocatalytic layers for hydrogen evolution reaction based on nickel phosphides: cost-effective fabrication and XPS characterization

Abstract The development of efficient electrocatalysts based on Pt-free materials is a crucial step for the maturation competitive water splitting technologies able to sustain upcoming hydrogen-based economy. In this context, present work optimizes codeposition/annealing methodology produce electrocatalytic layers hydrogen evolution reaction (HER) one most promising alternatives Pt-based catalysts: nickel phosphides. A nickel–phosphorus solid solution codeposited with red phosphorus microparticles and obtained composites are annealed promote interdiffusion between phosphorus. experimentation carried out demonstrates that properties final phosphide depend conditions employed in both codeposition annealing step. It fundamental evaluate optimize NiP/P process, it also important understand influence time temperature microstructure HER performance obtained. X-ray photoelectron spectroscopy (XPS) phase composition at surface, highlighting presence top layer characterized by Ni 2 P/Ni 12 P 5 ratio significantly lower than value found bulk coating. Annealed tested 0.5 M sulphuric acid solution. tests demonstrate clear correlation surface overpotential HER. Coherently, when outer -rich mechanically removed, overpotentials observed (169.5 mV vs. RHE 10 mA cm ?2 ).