Hierarchical flake-like Bi2MoO6/TiO2 bilayer films for visible-light-induced self-cleaning applications

Visible-light-induced self-cleaning properties of Bi2MoO6/TiO2 bilayer films have been realized by controlling the synthesis of hierarchical flake-like Bi2MoO6 on TiO2 nanoparticle film substrates by a solvothermal process. By tuning the reaction time, we could facilely prepare Bi2MoO6/TiO2 bilayer films with the desired surface morphology. UV-visible diffuse reflectance spectroscopy analysis indicated that the Bi2MoO6/TiO2 bilayer films can extend their absorption edges to the visible light region, and showed gradually enhanced visible light absorption because of the increase of Bi2MoO6 content and surface morphological change from flat to hierarchical flake-like structure. The hierarchical flake-like Bi2MoO6/TiO2 bilayer film showed more significant visible light self-cleaning performance than that of single Bi2MoO6 and TiO2 films. It could be attributed to the synergistic effect of surface hierarchical structure with large surface area, superhydrophilicity, and effective electron-hole separations at the interfaces of the two semiconductors, which was confirmed by surface photovoltage spectroscopy (SPS), photoluminescence (PL) and electrochemical tests.