Sulfur and Nitrogen Dual-Doped Molybdenum Phosphide Nanocrystallites as an Active and Stable Hydrogen Evolution Reaction Electrocatalyst in Acidic and Alkaline Media

Sulfur and nitrogen dual-doped molybdenum phosphides (MoP/SN) are synthesized via a (thio)urea-phosphate-assisted strategy in which the reductant (thio)urea acts as S and N source and phosphoric acid provides the P atom. The MoP/SN nanoparticles are generated by in situ phosphidation of indigenously synthesized ammonium phosphate-coated P-doped MoSx nanoparticles in a hydrogen atmosphere. Then, MoP/SN is anchored on graphene to obtain a hybrid electrocatalyst (MoP/SNG) that exhibits high activity and stability for electrochemical hydrogen evolution from water in both acidic and basic electrolytes, outperforming most MoP-based electrocatalysts reported in the literature. The dual doping and hybridization with graphene enhance electron conductivity of MoP and stabilize small MoP nanoparticles to increase activity and stability, especially in acid electrolytes.