Energy band matching Bi2WO6/black-TiO2 Z-scheme heterostructure for the enhanced visible-light photocatalytic degradation of toluene

Abstract

By exploiting the distinct band alignment characteristics of various semiconductors, the Z-scheme heterostructure represents a significant method to improve the effectiveness of energy conversion processes. In this work, Bi2WO6/Black-TiO2 (BTB) compounds are developed using the hydrothermal method combined with sol-gel method. It is shown that the separation efficiency of photoinduced carriers on BTB is visibly raised via establishing a Z-scheme system with matched energy band structures. The surface carrier separation efficiency is closely related to photocatalytic activity. Under visible light, the degrading performance of toluene over BTB heterostructure is found to be markedly enhanced. BTB-3 exhibits the optimal photocatalytic activity of the group, achieving a toluene conversion of 90% after 120 min reaction, which is twice and 5.5 times larger than that of B-TiO2 and Bi2WO6, respectively. Furthermore, developing of BTB Z-scheme heterostructure can preserve the catalyst's initial redox capacity, thereby producing more significant active species, e.g., ·OH and ·O2−radicals, to efficiently decompose toluene. According to in-situ DRIFTS data, acids, aldehydes and alcohols are among the intermediates that are collected during various stages of toluene's photocatalytic breakdown. This work supplies a fresh, workable route for future photocatalytic volatile organic compounds degradation.