Rational design of Au decorated Mn0.5Cd0.5S/WO3 step-scheme heterostructure with multichannel charge transfer and efficient H2 generation

[Display omitted] •Au decorated S-scheme Mn0.5Cd0.5S/WO3 composite synthesized for H2-production.•Mechanism of charge transfer and separation in Au decorated S-scheme discussed.•High H2-production rate achieved over composite, 2.74 folds higher than Mn0.5Cd0.5S. Spontaneously solar-driven H2-production from water reduction provides a promising strategy to solve the aggravating energy and environment crises worldwide, but it is severely limited by the rapid charge-carrier recombination and the slashing redox potentials requirement. Here, a new ternary Mn0.5Cd0.5S/WO3/Au heterostructure photocatalyst has been designed by chemical deposition of Au nanoparticles (NPs) on Mn0.5Cd0.5S/WO3 step-scheme (S-scheme) composite matrix to boost the photocatalytic activity through the multichannel-enhanced charge transfer/separation. By optimizing the constituent of the heterostructure photocatalyst, the prepared Mn0.5Cd0.5S/WO3/Au photocatalyst with 30 wt% of WO3 and 4 wt% of Au exhibits the highest H2-evolution rate of 517.13 µmol h−1 under simulated solar light irradiation, more 2.74, 1.63 and 1.45 times higher than bare Mn0.5Cd0.5S and Mn0.5Cd0.5S loaded with WO3 and Au alone, respectively. Mechanistic characterizations and control experiments have revealed that the S-scheme charge transfer in Mn0.5Cd0.5S/WO3 heterojunction together with the “electron reservoir” resulting from the Au NPs contribute to the superior H2-generation activity over Mn0.5Cd0.5S/WO3/Au catalyst, which not only dramatically promotes the charge-carrier separation but also remains the strong redox ability of photoinduced electrons and holes in such photocatalytic system.