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• Au decorated S-scheme Mn 0.5 Cd 0.5 S/WO 3 composite synthesized for H 2 -production. • Mechanism of charge transfer and separation in Au decorated S-scheme discussed. • High H 2 -production rate achieved over composite, 2.74 folds higher than Mn 0.5 Cd 0.5 S. Spontaneously solar-driven H 2 -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 Mn 0.5 Cd 0.5 S/WO 3 /Au heterostructure photocatalyst has been designed by chemical deposition of Au nanoparticles (NPs) on Mn 0.5 Cd 0.5 S/WO 3 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 Mn 0.5 Cd 0.5 S/WO 3 /Au photocatalyst with 30 wt% of WO 3 and 4 wt% of Au exhibits the highest H 2 -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 Mn 0.5 Cd 0.5 S and Mn 0.5 Cd 0.5 S loaded with WO 3 and Au alone, respectively. Mechanistic characterizations and control experiments have revealed that the S-scheme charge transfer in Mn 0.5 Cd 0.5 S/WO 3 heterojunction together with the "electron reservoir" resulting from the Au NPs contribute to the superior H 2 -generation activity over Mn 0.5 Cd 0.5 S/WO 3 /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. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel heterojunction consisting of multishelled hollow CaTiO 3 cubes and Co 0.2 Cd 0.8 S nanoparticles was designed. • An S-scheme charge transfer route within the heterojunction was confirmed. • Mechanism for the enhanced photoactivity over Co 0.2 Cd 0.8 S/CaTiO 3 heterojunction discussed. • High H 2 -production rate achieved over heterojunction, 3.58-fold higher than Co 0.2 Cd 0.8 S. Rationally designing S-scheme heterostructures with boosted charge separation efficiency and superior redox ability is regarded as an appealing strategy to conquer the shortcomings of mono-component and conventional heterojunction photocatalysts. Herein, a novel hierarchical S-scheme heterostructured photocatalyst was constructed by integrating Co 0.2 Cd 0.8 S nanoparticles on multishelled hollow CaTiO 3 cubes to substantially improve the photocatalytic hydrogen production activity. An internal electric field (IEF) is formed at the heterojunction interfaces owing to the significant disparity in Fermi level (E F) between Co 0.2 Cd 0.8 S and CaTiO 3 , accompanied by the energy band bending, which enables the S-scheme charge transport route in the Co 0.2 Cd 0.8 S/CaTiO 3 heterostructure, as verified by electron paramagnetic resonance and theoretical calculations. Benefiting from the boosted separation efficiency and superior redox capability of photocarriers within the constructed S-scheme heterostructure, the optimized Co 0.2 Cd 0.8 S/CaTiO 3 sample exhibited a significantly improved photocatalytic hydrogen evolution rate of 8.13 mmol h−1 g−1, far exceeding that of mono-component counterparts and previously reported Co 0.2 Cd 0.8 S- or CaTiO 3 -based photocatalysts. This study is anticipated to inspire the strategic development of other economical and efficient S-scheme photocatalytic systems with enhanced H 2 evolution activity. [ABSTRACT FROM AUTHOR]

[Display omitted] • Ternary Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction system was designed. • Synergetic effect between multifunctional CB and CuS dual cocatalysts discussed. • High H 2 -production rate achieved over composite, 4.79-fold higher than Mn 0.5 Cd 0.5 S. Developing exceptionally robust and cost-effective cocatalysts to suppress charge recombination and reduce the reaction energy barrier remains an enormous challenge for producing high-valued and storable hydrogen fuel from photocatalytic water splitting. Herein, novel Mn 0.5 Cd 0.5 S nanoparticles modified with multifunctional carbon black (CB) nanowires and CuS nanotubes as dual cocatalysts were fabricated via sonochemical loading, and subsequent in-situ deposition routes. In this ternary hierarchical architecture, both CB nanowires and CuS nanotubes can serve as normal electron cocatalysts to markedly promote the hydrogen generation performance by lowering the thermodynamic overpotential for hydrogen evolution. Moreover, due to the high electrical conductivity, the multifunctional CB material can also function as a bridge to effectively capture and transmit the photoexcited electrons from Mn 0.5 Cd 0.5 S to CuS with outstanding electrocatalytic hydrogen evolution activity, thus maximizing the carrier separation and H 2 -evolution reaction kinetics. Interestingly, the cooperative effects between CB and CuS dual cocatalysts are also helpful for improving the oxidation capacity of photoexcited holes by lowering the valence band position of Mn 0.5 Cd 0.5 S, which further accelerates the electron-hole separation. As a result, the constructed Mn 0.5 Cd 0.5 S/CB/CuS hierarchical multiheterojunction catalyst shows the superior hydrogen generation efficiency of 819.9 μmol h−1 and excellent stability under simulated solar light irradiation. [ABSTRACT FROM AUTHOR]