Bimetallic phosphide NiCoP anchored g-C3N4 nanosheets for efficient photocatalytic H2 evolution

Abstract

It is urgent to seek low-cost and highly efficient cocatalysts for accelerating H2 evolution in photocatalytic water splitting. In this work, bimetallic phosphide NiCoP was synthesized by a simple solvothermal method using red phosphorus as the P source. Then, NiCoP was anchored on the surface of g-C3N4 nanosheets via physical grinding followed calcination. The photocatalytic properties of NiCoP/g-C3N4 were compared in detail with those of monometallic phosphide/g-C3N4 systems (Ni2P/g-C3N4 and Co2P/g-C3N4). The investigation shows that the optimum H2 production rate over NiCoP/g-C3N4 is 5162 μmol g−1 h−1, which is obviously higher than that of the corresponding g-C3N4 (38.5 times), Ni2P/g-C3N4 (1.8 times), Co2P/g-C3N4 (1.6 times) and Pt/g-C3N4 (1.5 times). The apparent quantum yield (AQY) of H2 production over NiCoP/g-C3N4 reaches 18.5% at 400 nm. The superior activity of NiCoP/g-C3N4 is mainly attributed to the synergistic effects of both the excellent charge separation ability due to the Schottky barrier and the lower H2-evolution overpotential compared with the Ni2P or Co2P counterpart. This study further exploits other superior bimetallic phosphides as cocatalysts in the field of solar-to-hydrogen conversion.