Construction of BiOCl/Bi2WO6 Z-scheme heterojunction with close interfacial contact using CNT as electron medium

Abstract

Enhancing carrier separation capabilities and extending the visible light absorption range are essential for overcoming the low photocatalytic performance of single semiconductors. In this study, by using hydrothermal and ion-exchange methods, a series of Z-scheme heterojunction BiOCl/CNT/Bi2WO6 photocatalysts with visible light response were successfully constructed by using carbon nanotubes (CNT) as an electronic medium. Under visible light irradiation, the photocatalytic performances of the samples were evaluated by the degradation of tetracycline and ciprofloxacin. The results shown that the BiOCl/CNT/Bi2WO6 heterojunction photocatalysts possessed excellent photocatalytic activity, and the kinetics reaction models of the photocatalysts followed pseudo-first-order kinetics. This excellent photocatalytic performance may be due to the acceleration of photogenerated carrier separation due to the formation of heterojunction and the CNT as an electronic medium, as well as the close contact interface between the BiOCl/Bi2WO6 heterojunction, which shortened the carrier migration path. The charge transfer mechanism in the BiOCl/CNT/Bi2WO6 Z-scheme heterojunction composites was proposed based on the results of trapping experiments, in-situ XPS and SPV. Furthermore, three degradation pathways were discussed, and toxicity assessments of intermediates showed that the toxicity after photocatalytic degradation decreased. This study could bring light on the development of promising and novel CNT-mediated Z-scheme heterojunction photocatalysts for pollutant degradation.