Fabrication of TiO2 nanofibers assembled by Bi2WO6 nanosheets with enhanced visible light photocatalytic activity

Abstract

A series of Bi2WO6/TiO2 nanofibers (BT NF) hierarchical photocatalysts were synthesized by a facile two-step strategy consisting of electrospinning technique and subsequent solvothermal method. The results showed that the secondary two-dimensional Bi2WO6 nanosheets were uniformly assembled onto the surface of the TiO2 NF. It was also verified that the density of Bi2WO6 nanosheets could be tailed by controlling the precursor concentration during the solvothermal process. Photocatalytic tests demonstrated that BT NF with a low concentration of precursor (S1) possessed a much higher visible light degradation rate for Rhodamine B than TiO2 NF, Bi2WO6 and their mixture. The enhanced photocatalytic activity of S1 was ascribed to the extension of the light absorption region induced by the introduction of narrow band gap Bi2WO6, and the formation of heterojunction accelerating the interfacial charge separation. Moreover, BT NF with a high concentration of precursor (S2) manifested a higher photocatalytic activity than S1 due to the higher loading of Bi2WO6 nanosheets. S2 could be reused by sedimentation, and the photocatalytic activities of S2 were retained with a slight decline after four cycles, which confirmed its stability. Therefore, BT NF composites will be ideal candidates for highly efficient and recyclable photocatalysts for the treatment of organic pollutants under visible light.