Comprehensive investigation of the reciprocity of structure and enhanced photocatalytic performance in finned-tube structured TiO2/BiOBr heterojunctions

Finned-tube structured TiO2@BiOBr heterojunctions were synthesized via a facile and efficient solvothermal process. Field-emission scanning electron microscopy and transmission electron microscopy analyses demonstrated that the tunable uniform lamellar structured BiOBr nanoplates burgeoned from the surface of one-dimensional TiO2 nanotubes and constructed intimate interfacial junctions. The formation mechanism of the as-prepared TiO2@BiOBr heterojunctions was thus proposed. Owing to the combined effects of the intense visible light absorption, the efficient charge separation and lower recombination of photo-generated electron-hole pairs as well as larger specific surface area, the as-fabricated heterojunctions exhibited the best visible-light photocatalytic activity, structural stability and sustained cycling performance compared with the reported congeneric catalysts. Their degradation rate remained at 95.5% after seven cycles for the photodecomposition of RhB. A possible mechanism of the photocatalytic activity enhancement was also proposed based on the photocurrent measurements, the photoluminescence analysis and the radical trapping experiments. It revealed that the intimate interfacial junction could promote the separation of photo-generated charge carriers, simultaneously, both center dot O-2(-) and h(+) acted as the main reactive species in the rapid degradation of RhB under visible-light irradiation.