Layered WS2/WO3 Z-scheme photocatalyst constructed via an in situ sulfurization of hydrous WO3 nanoplates for efficient H2 generation

Abstract

Solar-driven H2 production over Z-scheme photocatalysts to mimic the natural photosynthesis represents a promising approach to the production of clean hydrogen energy. However, fabrication of Z-scheme heterostructures with intimate interfacial contact and smooth charge transfer for efficient H2 generation is still challenging. Herein, a series of layered WS2/WO3 heterostructures containing monoclinic WO3 (m-WO3) nanoplates and few-layer hexagonal WS2 with 2H structure (2H-WS2) is constructed via an in situ sulfurization process of hydrous WO3 nanoplates. The electronic interaction between the two moieties (2H-WS2 and m-WO3) follows a direct Z-scheme mechanism to retard the charge recombination without weakening the redox ability of the photoexcited charge carriers of the WS2/WO3 heterostructures. Moreover, the few-layer 2H-WS2 with thickness of ~4.2 nm and intimate interfacial contact between 2H-WS2 and m-WO3 due to the “S-W-O” transition layer can further provide shortened charge migration path and smooth interfacial charge transfer, which in turn enables the effective operation of the Z-scheme mechanism. Therefore, the WS2/WO3 Z-scheme photocatalyst with an optimal component ratio delivers ca. 5 times higher H2 generation activity than the few-layer 2H-WS2 alone. The present work offers a promising strategy to construct integrated nanostructured heterostructures with intimate interfacial contact, smooth charge transfer and improved photocatalytic performance.