Nitrogen, phosphorus dual-doped molybdenum-carbide/molybdenum-phosphide-@-carbon nanospheres for efficient hydrogen evolution over the whole pH range

MoO₄^2-@aniline-pyrrole (MoO₄^2-@polymer) spheres as precursors have been used to synthesize unique core-shell nanostructure consisting of molybdenum carbide and molybdenum phosphide composites encapsulated into uniformly dual N, P-doped carbon shells (Mo₂C/MoP@NPC) through a facile two-step strategy. Firstly, porous core-shell N-doped Mo₂C@C (Mo₂C@NC) nanospheres have been synthesized with ultrafine Mo₂C nanoparticles as core and ultrathin NC as shell by a annealing route. Secondly, Mo₂C/MoP@NPC has been obtained maintaining intact spherical-like morphology through a phosphidation reaction in high temperature. The synergistic effect of Mo₂C and MoP may reduce the strong MoH bonding energy of pure Mo₂C and provide a fast hydrogen release process. In addition, the dual N, P-doped carbon matrix as shell can not only improve the electroconductivity of catalysts but also prevent the corrosion of Mo₂C/MoP nanoparticles during the electrocatalytic process. When used as HER cathode in acids, the resulting Mo₂C/MoP@NPC shows excellent catalytic activity and durability, which only needs an overpotential of 160 mV to drive 10 mA cm^-2. Moreover, it also exhibits better HER performance in basic and neutral media with the need for overpotentials of only 169 and 228 mV to achieve 10 mA cm^-2, respectively. This inorganic-organic combination of Mo-based catalysts may open up a new way for water-splitting to produce large-scale hydrogen.