Fabrication of Bi2O3 QDs decorated TiO2/BiOBr dual Z-scheme photocatalysts for efficient degradation of gaseous toluene under visible-light

Weak visible-light capture ability, ultrahigh charge recombination rate, and poor redox ability are crucial constraints to improve the photocatalytic performance for toluene degradation under visible-light. Hence, a dual Z-scheme of Bi 2 O 3 quantum dots decorated TiO 2 /BiOBr photocatalysts (Bi 2 O 3 QDs@TiO 2 /BiOBr) were prepared by a two-step hydrothermal method . X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM) were performed to identify the existence of Bi 2 O 3 QDs and TiO 2 that loaded on the surface of BiOBr. The introducing of oxygen vacancies in TiO 2 broadened its light absorption region to the visible-light. The constitutes of Bi 2 O 3 QDs and BiOBr were regulated and the optimized photocatalyst BT1-B10 exhibited 94.1 % of removal rate for gaseous toluene degradation after 150 min irradiation of visible-light (>420 nm) as well as good recoverability and durability. This result was obviously superior to other comparison samples. In-situ DRIFTs spectra and Gas Chromatography-Mass Spectrometry (GC-MS) were carried out to provide a possible pathway for the toluene degradation. Additionally, a dual-channel electron transfer model based on the Z-scheme was proposed, which presented desirable visible-light response region, efficient charge separation efficiency, and enhanced redox ability. Notably, hydroxyl radicals (•OH) served as the dominant active species was confirmed by electron spin resonance (ESR) and gas-phase capture tests, that was beneficial to the ring-opening of toluene degradation. This dual Z-scheme heterojunction of Bi 2 O 3 QDs@TiO 2 /BiOBr photocatalyst showed great potential for the degradation of toluene under visible-light irradiation.