Engineering Nanostructured Bi_2WO_6-TiO_2 Toward Effective Utilization of Natural Light in Photocatalysis

摘要

Being expected as one of the most promising solutions in water and air purification as photocatalyst, TiO_2 is attracting intensive and extensive research interests globally despite its wide band gap (～3.2 eV for anatase structure) which limits it only to be activated under UV irradiation. In pursuit of extending the active region of TiO_2 toward visible light, considerable attention was devoted to develop TiO_2-based photocatalyst. We report herein, for the first time, novel "bud-on-branch" Bi_2WO_6-TiO_2 nanofibers fabricated via a facile and large-scale electrospinning technique from a biphased precursor. Formed by surface-decorating continuous TiO_2 nanofibers (mixed anatase-rutile system with an average diameter of about 100 nm) with ～13 nm well-crystallized Bi_2WO_6 nanopar-ticles, the as-synthesized Bi_2WO_6-TiO_2 nanofibers achieved an evidently increased specific surface area. Furthermore, corresponding photocatalytic experiments revealed that the optimal photodegradation rate from our designed heterostructure was as high as three times to that of pure TiO_2 nanofibers; this increase in optimal photodegradation rate is attributed to the relatively well-matched energy band between TiO_2 and Bi_2WO_6 and hence an excellent separation efficiency of photo-generated electron-hole pairs in both ultraviolet and visible light regions, suggesting that the designed heterostructures can give better rise to practise photocatalysis under natural light.