BiVO4@ZnIn2S4/Ti3C2 MXene quantum dots assembly all-solid-state direct Z-Scheme photocatalysts for efficient visible-light-driven overall water splitting

Abstract

Novel BiVO4@ZnIn2S4/Ti3C2 MXene quantum dots (QDs) assembly all-solid-state direct Z-scheme photocatalyst is fabricated via in-situ growth combined with two-step solvothermal strategy, which forms a hierarchical core-shell structure. The proper energy band structure of BiVO4 and ZnIn2S4 and the formation of a good solid-solid contact interface between them promote the construction of Z-scheme system, which achieves effective charge separation. It is surprisingly discovered that Ti3C2 MXene QDs can be applied as cocatalysts for photocatalytic overall water splitting, which could accelerate the surface redox kinetics of the catalyst due to the unique properties of Ti3C2 MXene QDs. In particular, due to its excellent metal conductivity, a Schottky barrier can be formed at the interface in contact with ZnIn2S4, further promoting charge separation. BiVO4@ZnIn2S4/Ti3C2 MXene QDs achieves effective visible-light-driven pure water splitting into O2 and H2 evolution rates up to 50.83 and 102.67 μmol g−1 h−1 (~1:2). In addition, it also shows high photocatalytic degradation Bisphenol A efficiency of ~96.4 %. The high photocatalytic performance can be ascribed to the all-solid-state direct Z-scheme structure favoring spatial charge separation, Ti3C2 MXene QDs as cocatalysts promoting proton reduction, and hierarchical core-shell structure offering more surface active sites. This work provides new insights to fabricate high-performance direct Z-scheme assembly system.