Bi5O7NO3 and Ag/Bi5O7NO3 composites: one-step solution combustion synthesis, characterization and photocatalytic properties

In the present study, Bi5O7NO3 and Ag/Bi5O7NO3 composites, as novel efficient photocatalysts, were synthesized via a one-step solution combustion synthesis (SCS) using bismuth nitrate (Bi(NO3)3·5H2O) as an oxidant, tartaric acid (C4H6O6) as a fuel, and silver nitrate (AgNO3) as an Ag source. The amount of Ag in the composite was tailored by varying the AgNO3 content during the SCS process. The orthorhombic Bi5O7NO3 crystal structure was confirmed by XRD, FT-IR and XPS. It was found by EDS and TEM that in the Ag-containing composite, Ag was uniformly distributed on the Bi5O7NO3 matrix. The Ag decoration improved the Bi5O7NO3 photocatalytic efficiency for methyl orange (MO) degradation, likely owing to the relatively low recombination rates of electrons and holes. The 5 mol% Ag/Bi5O7NO3 composite exhibited the best photocatalytic performance (95% in 60 min), which was 1.5 times higher compared to that of pure Bi5O7NO3. In addition, a mechanism of the photocatalytic MO degradation reaction was proposed, in which the reactive species O2− played an important role in degrading pollutants.