Facile synthesis of Bi2S3 nanocrystalline-modified TiO2: Fe nanotubes hybrids and their photocatalytic activities in dye degradation

Interface-induced effects and large specific area of heteronanostructures are attracting much attention due to applications in photocatalysis. In this work, ultrafine bismuth sulfide (Bi2S3) nanocrystalline-modified Fe-doped TiO2 nanotubes (NTs) were fabricated with facile methods. The effect of the ratio of Bi2S3 to the Fe-doped TiO2 NTs on the microstructural, optical, and photocatalytic properties of the NTs and hybrids was studied. The NTs showed an actual Fe content of approximate to 2.93at.%. The optical bandgap of the NTs and hybrids was approximate to 2.90eV and approximate to 2.46-2.88eV, respectively, and decreased with increasing Bi2S3/NTs ratio. The specific surface area of the NTs was approximate to 333m(2)g(-1); whereas the hybrids showed obviously larger specific surface area of approximate to 527-689m(2)g(-1) than the NTs because of well-controlled formation process of Bi2S3 nanoparticles. The sunlight-excited degradation experiments of dyes in the water indicated that the photocatalytic activity of the hybrids was higher than that of the NTs and increased with increasing Bi2S3/NTs ratio. Moreover, the degradation rates of two dyes at different initial pH values were very different. The high photocatalytic activity of the hybrids was mainly ascribed to the narrow bandgap, large specific surface area, and effective heterojunction.