Visually resolving the direct Z-scheme heterojunction in CdS@ZnIn2S4 hollow cubes for photocatalytic evolution of H2 and H2O2 from pure water

[Display omitted] •CdS@ZnIn2S4 hollow cubes are prepared which constitute highly efficient direct Z-scheme photocatalyst.•CdS@ZnIn2S4 can split pure water into H2 and H2O2 under visible light irradiation.•Visual differentiation between direct Z-scheme and Type II heterojunction is achieved by SPVM. The direct Z-scheme heterojunction has been recently emerging as an appealing architecture for photocatalysts design. Its efficiency depends on the interfacial and structural features of the photocatalysts. Herein, the two-dimensional ZnIn2S4 nanosheets are grown on the surface of CdS hollow cubes to construct the CdS@ZnIn2S4 hierarchical hollow photocatalysts with chemically bonded interface. The visualized measurements based on spatial-resolved surface photovoltage spectroscopy, combined with other spectroscopic and simulation investigations, clearly disclose that the CdS@ZnIn2S4 hollow cubes constitute a highly efficient direct Z-scheme system. This accounts for the stoichiometric generation of H2 and H2O2 from pure water observed for the CdS@ZnIn2S4 sulfide-only photocatalysts under visible light irradiation with an apparent quantum efficiency of 1.63 % at 400 nm. The present work demonstrates an effective protocol to achieve comprehensive insights into the charge transfer route at semiconductor heterojunction, and offers a viable way for constructing efficient sulfide-only photocatalysts for driving water splitting reaction.