Ultrathin Α-Mo ₂ C dominated by (100) Surface/Cu Schottky junction as efficient catalyst for hydrogen evolution

High-performance catalysts for hydrogen evolution reaction (HER) have been targeted for decades, ideally based on earth-abundant elements to replace expensive platinum. Several promising candidates have been reported, but catalysts with excellent conductivity, outstanding HER thermodynamics, kinetics and long durability are still extensively searched. In this work, we investigated the HER performance of micrometer-sized ultrathin α-Mo ₂ C nanosheets dominated by minority surface (100) grown on copper foil by chemical vapor deposition (CVD). Such α-Mo ₂ C/Cu Schottky junction electrode offers excellent durability and conductivity, together with small HER overpotential and ultralow Tafel slope (33.7 mV·dec ⁻¹ ), making it comparable to Pt/C catalyst. First principal calculations revealed the reaction path of hydrogen evolution over (100) surface, and clarified that the electron injection from the Cu substrate plays the key role for the observed performance.