A compact Z-scheme heterojunction of BiOCl/Bi2WO6 for efficiently photocatalytic degradation of gaseous toluene

Construction of Z-scheme heterojunction photocatalysts with efficient electron-hole pairs separation and robust oxidation abilities is a promising strategy to decompose volatile organic compounds (VOCs). Herein, UV-light-driven BiOCl and visible-light-driven Bi2WO6 were successfully combined via a one-pot hydrothermal method and compact Z-scheme heterojunction photocatalyst BiOCl/Bi2WO6 was obtained. Owing to the similar precursors and synthesis conditions, the integrated BiOCl/Bi2WO6 heterojunction was intimate and homogenous, which resulted in the efficient separation of photogenerated carriers, and generated abundant holes (h+), hydroxyl radicals (·OH) and superoxide radicals (·O2-). The optimal BiOCl/Bi2WO6 photocatalyst (BWOCl-2), achieved by tailoring the amount of hydrochloric acid, exhibited almost 100 % of toluene degradation and excellent durability. Electron spin resonance (ESR) results revealed that h+, ·O2- and ·OH were dominant active species in the BiOCl/Bi2WO6 photocatalytic system. The degradation intermediate products were monitored by in situ Diffuse Reflection Infrared Fourier Transform spectroscopy (DRIFTS) and the possible photocatalytic mechanism was also revealed according to the band structure of BiOCl/Bi2WO6 heterojunction. This work provided a novel avenue to design an efficient homogenous heterojunction photocatalyst for the efficient degradation of VOCs under sunlight.