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

Abstract

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.