Benchmarking Phases of Ruthenium Dichalcogenides for Electrocatalysis of Hydrogen Evolution: Theoretical and Experimental Insights

The hydrogen evolution reaction (HER) is a significant cathode step in electrochemical devices, especially in water splitting, but developing efficient HER catalysts remains a great challenge. Herein, comprehensive density functional theory calculations are presented to explore the intrinsic HER behaviors of a series of ruthenium dichalcogenide crystals (RuX₂, X = S, Se, Te). In addition, a simple and easily scaled production strategy is proposed to synthesize RuX₂ nanoparticles uniformly deposited on carbon nanotubes. Consistent with theoretical predictions, the RuX₂ catalysts exhibit impressive HER catalytic behavior. In particular, marcasite-type RuTe₂ (RuTe₂-M) achieves Pt-like activity (35.7 mV at 10 mA cm⁻²) in an acidic electrolyte, and pyrite-type RuSe₂ presents outstanding HER performance in an alkaline media (29.5 mV at 10 mA cm⁻²), even superior to that of commercial Pt/C. More importantly, a RuTe₂-M-based proton exchange membrane (PEM) electrolyzer and a RuSe₂-based anion exchange membrane (AEM) electrolyzer are also carefully assembled, and their outstanding single-cell performance points to them being efficient cathode candidates for use in hydrogen production. This work makes a significant contribution to the exploration of a new class of transition metal dichalcogenides with remarkable activity toward water electrolysis.