Rational Electron Transmission Structure in an Ag2O/TiO2(anatase-B) System for Effective Enhancement of Visible Light Photocatalytic Activity

Titanium dioxide has received great attention as a photocatalyst. However, due to the relatively large bandgap energy of TiO2 and fast recombination of photo-generated electron-hole pairs, various attempts have been made to improve its photocatalysis, including reasonable energy band construction for broadening light absorption and effectively separating photogenerated electron-hole pairs. In this work, a reasonable energy band construction is realized by an Ag2O/TiO2(anatase-B) heterostructure system. The Ag2O/TiO2(anatase-B) microspheres aggregated by radially aligned nanosheets are synthesized by a one-step sol-gel solvothermal method. The Ag2O nanoparticles are uniformly coated on TiO2(anatase-B) microspheres with a diameter of 2.5-4.5 mu m. Compared with P25 and TiO2(anatase-B), the photocatalytic activity of the Ag2O/TiO2(anatase-B) heterostructure is obviously enhanced under visible-light irradiation with the degradation of methyl orange. The photocatalytic mechanism of Ag2O/TiO2(anatase-B) microspheres is proposed. Four different ways of photoelectron transportation is apparently involved in the photodegradation. This work demonstrates that reasonable energy band construction by a three-component heterostructure not only favors visible light harvesting but also promotes the separation of photogenerated electron-hole pairs.