BiOBr nanosheets-decorated TiO2 nanofibers as hierarchical p–n heterojunctions photocatalysts for pollutant degradation

Engineering semiconductor-based homo- (hetero-) junctions in hierarchical nanostructures is a promising way to achieve the high performance and recyclable photocatalysts toward pollutants degradation in water. Herein, we develop a kind of hierarchical p–n heterojunctions photocatalysts through controllable decoration of ultrathin p-BiOBr nanosheets onto n-TiO2 electrospun nanofibers by using a traditional solvothermal method. Structural characterization results indicate that the BiOBr nanosheets are assembled uniformly onto the TiO2 nanofibers. This well-designed hierarchical p–n heterojunctions in the p-BiOBr/n-TiO2 nanofibers photocatalyst lead to not only the improved generation/separation of photoinduced charges-carriers, but also the increased amount of redox sites. Benefiting to these advantages, the optimal p-BiOBr/n-TiO2 nanofibers exhibited the apparent rate constant of 0.1 and 0.15 min−1 for photocatalytic RhB and MO degradation under UV-light irradiation, which is twice and three times higher than that of mechanically mixtured BiOBr nanosheets and TiO2 nanofibers, respectively. Control experiments demonstrate that both the photoinduced electrons and the oxygen free radicals play the major roles on the enhancement of photocatalytic activity. Moreover, the p-BiOBr/n-TiO2 nanofibers photocatalysts with the unique nonwoven structure can be easily recycled without secondary pollution, in particular, still maintaining almost the initial photocatalytic activity during the wastewater treatment.