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.