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

Abstract

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.