Novel multi-heterostructured Pt-BiOBr/TiO2 nanotube arrays with remarkable visible-light photocatalytic performance and stability

Unique multiple heterojunction of Pt-BiOBr/TiO2 nanotube arrays（Pt-BiOBr/TNTAs） was achived by successively loading both Pt nanoparticles（NPs） and BiOBr nanoflkes（NFs） on surface of ordered and spaced TiO2 nanotubes（NTs） using anodization followed by solvothermal and sequential chemical bath deposition（S-CBD） method. The fabricated Pt-Bi OBr/TNTAs were fully characterized, and the photocatalytic（PC） activity and stability of PtBiOBr/TNTAs toward degradation of methyl orange（MO） under visible-light irradiation（λ＆gt;400 nm） were evaluated. The results reveal that multiple heterostructures of Pt/TiO2, Pt/BiOBr and BiOBr/TiO2 are constructed among TNTAs substrate, Pt NPs and BiOBr NFs, and the hybrid Pt-BiOBr/TNTAs catalyst exhibits remarkable visible-light PC activity, favourable reusability and long-term stability. The combined effect of several factors may contribute to the remarkable PC performance, including strong visible-light absorption by both Pt NPs and BiOBr NFs, lower recombination rate of photo-generated electrons and holes attributed to the multiple heterojunction, microstructures for facile light injection and adsorption as well as efficient mass transport, and larger specific surface area for enhancing light absorption, increasing the effective contact area between the absorbed dye molecules and catalyst and benefiting the molecule transport of reactants or products.