High-performance hydrogen evolution at a MoSe2–Mo2C seamless heterojunction enabled by efficient charge transfer

Abstract

Transition metal dichalcogenides (TMDs), such as molybdenum diselenide (MoSe₂), have poor alkaline hydrogen evolution activities due to their unfavorable hydrogen adsorption and dissociation properties. In this work, we report a Mo₂C/MoSe₂ hybrid catalyst seamlessly grown on Mo foil. The Mo₂C/MoSe₂/Mo electrode exhibits outstanding activity for the hydrogen evolution reaction (HER) with a low overpotential of 51 mV at 10 mA cm⁻² in 1 M KOH, significantly outperforming the performances of its MoSe₂ and Mo₂C counterparts and most reported TMD electrocatalysts in alkaline solution. Moreover, the Mo₂C/MoSe₂/Mo electrode also possesses good catalytic HER performance in acid. Density functional theory (DFT) calculations reveal that metal-induced gap states formed in the interface region of Mo₂C and MoSe₂ can make the interfacial semiconducting MoSe₂ transform into metallic MoSe₂. The transformation is beneficial to speeding up charge transfer between the interfaces, promoting H atom adsorption and desorption kinetics, and therefore enhancing the catalytic performance.