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[Display omitted] • Direct Z-scheme Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction was designed. • Mechanism for the enhanced photoactivity over Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction discussed. • High ammonia production rate achieved over heterojunction, 5.1-fold higher than Mn 0.5 Cd 0.5 S. The exploration and design of highly efficient and robust photocatalysts composed of earth-abundant materials for ambient photocatalytic N 2 fixation to ammonia remains a significant challenge. Here, we have fabricated a stable and highly efficient direct Z-scheme Mn 0.5 Cd 0.5 S/CoTiO 3 heterostructure for N 2 fixation by depositing Mn 0.5 Cd 0.5 S nanoparticles on CoTiO 3 surface. Under ambient conditions, the optimized Mn 0.5 Cd 0.5 S/CoTiO 3 heterojunction achieved a significant NH 3 production rate of 121.9 μmol g-1h−1 without cocatalyst modification, representing a 5.1- and 5.9-fold increase over pristine Mn 0.5 Cd 0.5 S and CoTiO 3 , respectively, and also exceeding most previously reported photocatalytic systems. The significant improvement in ammonia production primarily results from the Z-scheme charge transfer path between the Mn 0.5 Cd 0.5 S and CoTiO 3 components, which enables effective separation of photoinduced carriers while maintaining their robust redox capacity, thus dramatically boosting ammonia generation performance. This research may provide new insights for advancing other alternative Z-scheme photocatalytic systems with remarkable stability and exceptional efficiency in N 2 fixation. [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]