Graphite sheet-supported bimetallic RhNi thin film alloys for enhanced and durable hydrogen evolution in acidic environments

Noble metal-based materials are excellent catalysts for hydrogen production from water electrolysis, but their high cost and limited availability hinder widespread use. However, precious metals can be effectively utilized in catalysts by forming alloys with low-cost 3d transition metals, thereby reducing the need for precious metals, while enhancing the performance. In this study, aerosol-assisted chemical vapor deposition was employed to deposit bimetallic rhodium-nickel (RhNi) alloy thin films on a graphite sheet for hydrogen evolution reaction (HER) catalysis in a 0.5 M H₂SO₄ solution. Thin-film morphological patterns were significantly changed as the deposition time varied from 45 to 135 min. The RhNi alloy fabricated for 90 min outperformed its counterparts, displaying lower overpotential of 40 and 197 mV at 10 and 1000 mA cm⁻², small Tafel kinetics (54 mV dec⁻¹), high conductivity (0.57 Ω) and large electrochemical surface area (3312 cm²), and extended stability (48 h) compared to pure Rh metal and other reported catalysts. The superior HER performance arises from the synergistic effects between Rh and Ni metals, coupled with a uniform layer of spherical particles that enhance conductive properties and reaction rates by providing maximized active sites on graphite surface. This work provides valuable guidelines for efficiently preparing highly active and durable thin-film electrocatalyst within short time span and applying directly in fuel cell for hydrogen production.