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• Mn 0.5 Cd 0.5 S decorated with Au and MoO 2 dual cocatalysts synthesized for H 2 -production. • Synergetic effects between the multifunctional Au NPs and MoO 2 cocatalysts discussed. • High H 2 -production rate achieved over composite, 3.73 folds higher than Mn 0.5 Cd 0.5 S. The construction of semiconductor-based nanoheterostructures toward achieving high efficient solar-to-fuel conversion is greatly limited by the insufficient electron-hole separation and the narrow spectrum range of light absorption. In this work, a novel Mn 0.5 Cd 0.5 S solid solution decorated with robust and multifunctional MoO 2 and Au nanoparticles (NPs) has been constructed by a facile two-step route: the deposition of Au NPs via an in situ deposition route and further loading of MoO 2 via an ultrasonic chemical method. Characterization results show that both MoO 2 and Au NPs can be employed as efficient cocatalytic materials to significantly promote the H 2 -production over Mn 0.5 Cd 0.5 S semiconductor. Particularly, the ternary 2MoO 2 /3Au/Mn 0.5 Cd 0.5 S nanocomposite containing 3 wt% Au NPs and 2 wt% MoO 2 exhibited the optimum H 2 -production activity (638.83 µmol h−1) under simulated sunlight conditions, more 3.73-, 1.74- and 1.35-fold enhancement relative to pristine Mn 0.5 Cd 0.5 S, binary 3Au/Mn 0.5 Cd 0.5 S and 2MoO 2 /Mn 0.5 Cd 0.5 S, respectively. Mechanistic characterizations demonstrate that the positive synergetic effects between Au NPs and MoO 2 can simultaneously boost the light absorption capacities, the separation efficiency of the interfacial charge carriers, and the thermodynamic performances of the hydrogen evolution reaction by strengthening the reduction ability of the photogenerated electrons and lowering the hydrogen evolution overpotential, which integratively resulted in the boosted photoactivity. [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]

The rational design of hierarchical heterojunction photocatalysts with efficient spatial charge separation remains an intense challenge in hydrogen generation from photocatalytic water splitting. Herein, a noble-metal-free MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 ternary heterostructure with a hierarchical flower-like architecture was developed by in situ growth of 3D flower-like ZnIn 2 S 4 nanospheres on 2D MoS 2 and 2D g-C 3 N 4 nanosheets. Benefiting from the favorable 2D-2D-3D hierarchical heterojunction structure, the resultant MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 nanocomposite loaded with 3 wt% g-C 3 N 4 and 1.5 wt% MoS 2 displayed the optimal hydrogen evolution activity (6291 μmol g−1 h−1), which was a 6.96-fold and 2.54-fold enhancement compared to bare ZnIn 2 S 4 and binary g-C 3 N 4 /ZnIn 2 S 4 , respectively. Structural characterizations reveal that the significantly boosted photoactivity is closely associated with the multichannel charge transfer among ZnIn 2 S 4 , MoS 2 , and g-C 3 N 4 components with suitable band-edge alignments in the composites, where the photogenerated electrons migrate from g-C 3 N 4 to ZnIn 2 S 4 and MoS 2 through the intimate heterojunction interfaces, thus enabling efficient electron-hole separation and high photoactivity for hydrogen evolution. In addition, the introduction of MoS 2 nanosheets highly benefits the improved light-harvesting capacity and the reduced H 2 -evolution overpotential, further promoting the photocatalytic H 2 -evolution performance. Moreover, the MoS 2 /g-C 3 N 4 /ZnIn 2 S 4 ternary heterostructure possesses prominent stability during the photoreaction process owing to the migration of photoinduced holes from ZnIn 2 S 4 to g-C 3 N 4 , which is deemed to be central to practical applications in solar hydrogen production. [ABSTRACT FROM AUTHOR]