Supercritical Carbon Dioxide Introduced a 2H to 1T Phase Transition in Ru/MoSe2 with Enhanced Hydrogen Evolution Performance

The development of highly efficient hydrogen evolution reaction (HER) catalysts for water splitting is one of the most promising strategies to achieve peak CO₂ emission and carbon neutrality targets. In this study, we demonstrate a supercritical carbon dioxide (SC CO₂)-assisted phase transition strategy to engineer metastable 1T phase Ru/MoSe₂ from its 2H phase counterpart. Experimental and theoretical results reveal that the incorporation of Ru significantly lowered the kinetic energy barrier of the 2H → 1T phase transition, while the introduction of SC CO₂ provides additional support for the long-term stability of the 1T phase, thus facilitating the phase transition of MoSe₂. The synergistic combination of Ru’s exceptional water dissociation capability and the superior intrinsic conductivity and catalytic efficiency of 1T-MoSe₂ creates an optimized electronic structure that significantly enhances HER kinetics. Specifically, the optimized SC Ru/MoSe₂ exhibits remarkable catalytic performance, achieving an ultralow overpotential of 52 mV at 10 mA cm^–2 with a Tafel slope of 32 mV dec^–1 in 1 M KOH, overperforming commercial Pt/C benchmarks.