A strategy for highly dispersed Mo₂C/MoN hybrid nitrogen-doped graphene via ion-exchange resin synthesis for efficient electrocatalytic hydrogen reduction

Molybdenum carbide/molybdenum nitride hybrid N-doped graphene (abbreviated as Mo₂C/MoN/NG), as an efficient electrocatalyst for the hydrogen evolution reaction (HER), was synthesized via simple ion-exchange resin synthesis followed by a two-step annealing process, which increased the dispersion degree of the electrocatalyst's active sites on the support skeleton and simplified the synthetic conditions. Additionally, N-doped graphene (NG) enhanced the electron transfer and reduced the inner resistance. The material has a graphene-like morphology and highly dispersed Mo2C/MoN nanoparticles about 2 nm in diameter on the NG. X-ray photoelectron spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy revealed that Mo₂C/MoN/NG consisted of Mo₂C and MoN composited together. Finally, Mo₂C/MoN/NG exhibited remarkable performance as an electrocatalyst for the HER with a small overpotential of 78.82 mV and a small Tafel slope of 39.3 mV·dec^-1 in a 0.5 mol·L^-1 H₂SO₄ solution. Its activity was approximately 30% lower than that of 20% Pt/C and 60% higher than that of NG. Also, it exhibited a low onset overpotential of 24.82 mV, which is similar to the theoretical HER potential. Our work provides a foundation for advanced HER applications of molybdenum compounds.