Synergistic optimization of RuNi alloy thin films via aerosol-assisted chemical vapor deposition for efficient hydrogen evolution in acidic media

Ruthenium (Ru)-based catalysts are promising alternatives to platinum (Pt) for the hydrogen evolution reaction (HER) due to their comparable hydrogen adsorption properties and lower cost. Efficient synthesis of Ru catalysts for achieving high current density and stability has become crucial for large-scale hydrogen production via water electrolysis. This work demonstrates that RuNi alloy thin films fabricated through a simple aerosol-assisted chemical vapor deposition process show great promise for HER under acidic conditions. The alloy catalyst, designed with an optimized 1:1 elemental composition, exhibits a granular morphology and facilitates strong synergistic electronic interactions between Ru and Ni. This all leads to develop an outstanding catalytic performance, including a current density of 1 A cm⁻² at an overpotential of 152 mV, a low Tafel slope of 38 mV dec⁻¹ and high electrochemical surface area. The robust RuNi thin film maintains continuous HER activity for 45 h at 25 and 50 mA cm⁻² without changes in composition or morphology. Density functional theory calculations reveal that Ni weakens hydrogen adsorption on Ru sites and enhances charge transfer between Ru and Ni, which drives the significantly improved HER activity. This work emphasizes fabricating thin-film catalysts via a tailored CVD process to achieve promising water-splitting performance.