Phase-controllable NixMoyPz dual-cocatalyst regulates electron transfer for enhanced photocatalytic hydrogen evolution

The rational design and construction of low-cost nickel molybdenum phosphides (NixMoyPz) cocatalysts for hydrogen evolution have aroused wide concern in recent years. However, NixMoyPz involves so many stoichiometric compositions with various crystal phase, thus, fabricating NixMoyPz with excellent hydrogen evolution activity and revealing their intrinsic mechanism at atomic level become crucial problems. Herein, a novel phase-controllable phosphating method by reasonably introducing various amounts of PH3 deriving from red phosphorus is firstly proposed to synthesize NiMoP/ZnxCd1-xS (NMP/ZCS), NiMoP/NiMoP2/ZnxCd1-xS (NMPP2/ZCS) and NiMoP2/ZnxCd1-xS (NMP2/ZCS) photocatalysts. The experimental and theoretical results reveal that this novel NMPP2 dual-cocatalyst maximumly accelerates photoelectrons transfer into the outmost layer of NMP2 component, meanwhile, under the intense synergy among NiMoP and NiMoP2 components, NMPP2 dual-cocatalyst further promotes the dissociation of H2O and the desorption of hydrogen proton. Accordingly, the optimized NMPP2/ZCS heterojunction reveals the best photocatalytic hydrogen evolution (PHE) efficiency of 83.54 mmol h−1 g−1 without an evident decrease after 6 cycles of photocatalytic tests in the Na2S-Na2SO3 solution, which is 25.55, 1.6 and 1.24 times higher than these of Pt/ZCS, NMP/ZCS and NMP2/ZCS, respectively. This tactic hews out a new way for optimizing photocatalysis by the construction of dual-cocatalyst to enhance the activity of PHE.