LAUSR

Abstract Bismuth oxyfluoride compounds have been intensively investigated as optical materials for multifunctional applications. In this work, preparation, optical and photocatalytic properties of a novel bismuth oxyfluoride BiTe3O7F were reported. To modify the performances, Bi1-4x/3Te3+xO7F (x = 0, 0.05, 0.1, 0.12, −0.05, −0.1, −0.12) was further designed with stoichiometry alteration between Bi3+ and Te4+. All the samples were synthesized via by sol–gel routine combined with a solid-state reaction method. Stoichiometry exchanges between nonmetal Te4+ and metal Bi3+ ions can be homogeneously realized in the lattices of Bi1-4x/3Te3+xO7F (x = 0, 0.05, 0.1, 0.12, −0.05, −0.1, −0.12). BiTe3O7F shows a typical indirect allowed transition with band energy of 2.917 eV. The deviation of Te:Bi from the stoichiometry requirement in BiTe3O7F (3:1) could modify the band gap in different ways, that is, the excess (x > 0) and lack (x  >  -0) of Te3+ make the band gap widen and narrow, respectively. The photocatalytic activities could be enhanced via substitution between Te4+ and Bi3+ cations in BiTe3O7F, especially, the improvement is more noticeable for the Te3+ excess (x>0) in the lattice. To discuss the mechanisms, XPS measurements and annealing treatments were conducted. The enhanced photodegradation could be ascribed to the changes of anion microstructure in the surfaces. The present results could be a reliable reference in the development of the photochemical application of bismuth oxyfluoride semiconductors.