Preparation And Photocatalytic Properties Of Bi₂WO₆/TiO₂ Micro-Nanofibers

Bismuth（Bi₂WO₆） was regarded as a perovskite type semiconductor, with a band energy of 2.70 eV, photocatalytic activity under visible light has become a hot topic of research in recent years, however, in practical application, a higher recombination rate of photo-induced charge carriers damaging its photocatalytic efficiency. Titanium dioxide（TiO₂） is an ideal photocatalyst because of its non toxicity, chemical stability, strong oxidation ability, low cost and no secondary pollution, however, the wide band energy of3.2 eV, which lead to the low utilization rate of sunlight.This paper aims to study the photocatalytic properties of Bi₂WO₆/TiO₂ composite micro-nano materials contained by electrospinning technique combined with sol-gel method, then the electrospun precursors were calcined at different temperatures. The physicochemical properties of the catalysts were characterized by XRD, FT-IR, FE-SEM,XPS and UV-Vis. The photocatalytic activity of the sample toward the decomposition of Methylene Blue（MB）was investigated. The effects of V₂O₅ doping and doping content on the structure, morphology and photocatalytic properties of Bi₂WO₆ were analyzed, The preparation, structure and photocatalytic properties of Bi₂WO₆/TiO₂ composite micro-nano materials were studied, and further study on the photocatalytic mechanism of different types of micro-nano materials.（1）Bi₂W_1-xV_xO_6-δ micro-nanofiber were fabricated via calcining the as-synthesized precursors fibrous mat prepared by electrospinning technique route using Bi（NH3）2C6H7O7·H2O、H42N10O42W12、NH4VO3 and PVP as regent. The results indicated that doping V₂O₅ could improve the catalytic properties of Bi₂WO₆ catalyst. The results revealed that 3 at.% VO2.5 doping exhibited the highest photocatalytic activity under visible light irradiation. After visible light irradiation for 120 min, the degradation rate of MB（10 mg/L） reached 86.9 %, improved 15 % comparing to the pure Bi₂WO₆ sample.（2）Bi₂WO₆/TiO₂ composite micro-nano fibers prepared by two-step electrospinning technique route. The results indicated that defect sites of imcompletely carbonized Bi₂WO₆ fibers were favorable for the growth of TiO₂ nanoparticles. The form of Bi₂WO₆/TiO₂ heterostructure is propitious to the effective separation of photo-induced charge carriers,broaden the visible light response range of TiO₂. The photocatalytic activity of the TiO₂/Bi₂W_1-xV_xO_6-δ（X=0, 0.3）sample was higher than the pure TiO₂ sample（45.3 %）.After visible light irradiation for 120 min, the degradation rate of MB（10 mg/L） reached72.6 % and 81.8 % respectively.