Synthesis and structural characterization of novel visible photocatalyst Bi-TiO2/SBA-15 and its photocatalytic performance

Bi-doped TiO2/SBA-15 (Bi-TiO2/SBA-15) was synthesized by a wet impregnation method. It was found that SBA-15 retained its ordered hexagonal mesostructure after incorporation of TiO2 and Bi. TiO2 nanoparticles and Bi species dispersed well and anchored both in the channel and the wall of SBA-15. The photocatalytic activity was evaluated on photodegradation of Rhodamine B (RhB) under visible light irradiation (lambda >= 420 nm). Experimental results indicated that Bi-TiO2/SBA-15 exhibited higher photocatalytic activities than pure TiO2 and TiO2/SBA-15 owing to the synergetic effects of Bi species and TiO2. The degradation of RhB by these catalysts follows the pseudo-first-order kinetic model and Bi-TiO2/SBA-15 (2.0%) was found to be the best. The effect of Bi doping on the photocatalytic activity was investigated by the density functional theory (DFT) method. The calculated results indicated that Bi doping could improve the photocatalytic activity by extending the spectral response from UV to the visible region, making the Bi-TiO2/SBA-15 active under visible light irradiation.