All-solid-state WO3/TQDs/In2S3 Z-scheme heterojunctions bridged by Ti3C2 quantum dots for efficient removal of hexavalent chromium and bisphenol A

Ti3C2 quantum dots (TQDs) derived from ultrathin few-layered Ti3C2 nanosheets were served as the low-cost solid electron mediator of photogenerated carriers at the semiconductor interfaces, which could greatly reserve the reductive and oxidative reaction sites on the surface of heterojunctions and accelerate the reduction and oxidation reactions. The all-solid-state TQDs-bridge WO3/TQDs/In2S3 Z-scheme photocatalysts exhibited extremely promoted photocatalytic reduction of Cr (VI) and photocatalytic oxidation of Bisphenol A (BPA) under visible light irradiation, which are 4 and 3 times higher than that of WO3/In2S3 heterojunctions, respectively. The favorable photocatalytic activities of WO3/TQDs/In2S3 should attribute to the effective electron transfer and charges separation with introduction of TQDs as the electron mediators in the Z-scheme system. In addition, the stability of WO3/TQDs/In2S3 was investigated and the possible mechanisms during photo-reduction of Cr(VI) and photo-oxidation of BPA were proposed. This work provides a new strategy for fabrication of all-solid-state Z-scheme heterojunctions using Ti3C2 quantum dots as the low-cost solid electron mediator for efficient environmental remediation.

Automated summary

Ti3C2 quantum dots were used as a low-cost solid electron mediator in all-solid-state Z-scheme photocatalysts, significantly promoting photocatalytic reduction of Cr (VI) and photocatalytic oxidation of Bisphenol A (BPA) under visible light irradiation. The introduction of TQDs as electron mediators facilitated effective electron transfer and charge separation, leading to improved photocatalytic activity.