Ultrafine molybdenum carbide nanoparticles supported on nitrogen doped carbon nanosheets for hydrogen evolution reaction

Molybdenum carbides (Mo_xC)/nitrogen doped carbon nanosheets (NCS) composites are synthesized via simple mixing melamine and ammonia molybdate, followed by a high-temperature treatment. Metal carbide nanoparticles with ultra-small size (1―3 nm) are uniformly supported on nitrogen doped carbon nanosheets. The hydrogen evolution reaction (HER) is investigated in both 0.5 mol/L H₂SO₄ and 1 mol/L KOH media. Mo₂C/NCS-10 (melamine/ammonia molybdate weight ratio of 10:1) exhibits excellent performance with a low overpotential of 130 mV in 0.5 mol/L H₂SO₄ solution and 108 mV in 1 mol/L KOH solution at the current density of 10 mA/cm². The better electrocatalytic activity could be ascribed to N-doped carbon nanosheets, small particle size, mesoporous structure, and large specific surface area, which could provide the large electrochemical active surface area and facilitate mass transport.