Molybdenum Carbide Anchored on N,S Co-Doped Carbon Composite Derived from Lignosulfonate as a High Performance Electrocatalyst for Hydrogen Evolution Reaction

A composite of Mo₂C nanoparticles dispersed onto a nitrogen and sulfur co-doped carbon scaffold (Mo₂C/N,S-C) was prepared by a simple and environmentally friendly method of one-pot annealing of MoCl₅, urea, and lignosulfonate under a N₂ atmosphere at 700 °C. Lignosulfonate, a by-product of the sulfite pulping process, was employed as a feedstock to fabricate the S-doped carbon scaffold and carbide simultaneously, and urea acted as a nitrogen source for N-doping to carbon. The as-prepared Mo₂C/N,S-C catalyst showed high performance for the hydrogen evolution reaction (HER), with a small overpotential of 105 mV at 10 mAcm⁻², and good stability for 3000 cycles. The improved HER performance of the Mo₂C/N,S-C originated from the interplay between the highly active Mo₂C nanoparticles and the N,S co-doped carbon scaffold with its high electrical conductivity and large surface area. Furthermore, N,S co-doping to carbon improved the hydrophilicity of the catalyst surface, thus further enhancing the HER activity.