Fabrication and characterization of BiOBr-SnWO4 heterojunction nanocomposites with boosted photodegradation capability

Novel BiOBr-SnWO4 heterojunction nanocomposites were fabricated by chemical precipitation method using as-prepared SnWO4 nanoparticles, bismuth nitrate as a source of bismuth, KBr as a source of Br, and ethylene glycol as solvent. The prepared BiOBr-SnWO4 heterojunction nanocomposites were examined for phase structure, chemical composition, surface morphology, optical properties, and charge transport by XRD, XPS, TEM, UV-Visible NIR, photoluminescence (PL), time-resolved fluorescence spectroscopy, electrochemical impedance spectroscopy (EIS), and Brunauer-Emmett-Teller (BET) analysis. X-ray diffractogram of BiOBr-SnWO4 nanocomposites revealed the diffraction peaks corresponding to orthorhombic SnWO4 nanoparticles in the tetragonal BiOBr which indicated that they exist in the mixed-phase in the composite. TEM pictures confirmed the existence of SnWO4 nanostructure in the BiOBr particles yielding core-shell particles. PL, fluorescence lifetime, and EIS investigations of the prepared samples showed a good charge separation efficiency in the BiOBr-SnWO4 -1 nanocomposite. The application of BiOBr-SnWO4 nanocomposites as a photocatalyst was investigated via the decomposition of an aqueous solution of rhodamine B (RhB) and brilliant green (BG) dyes in the natural sunlight. Among the prepared materials, the BiOBr-SnWO4 -1 nanocomposite presented robust photodegradation capability towards the degradation of RhB and BG dyes. The degradation efficiency touched to 97.85% and 95.5% for RhB and BG, respectively. The superior performance of BiOBr-SnWO4 -1 is attributed to the existence of heterojunction between p-type BiOBr and n-type SnWO4 nanoparticles along with an improved visible light absorption capacity of heterojunction and the efficient interfacial charge transfer/ separation. The radical scavenger investigations showed that photogenerated h +, O2 center dot-, and center dot OH radicals generated by the photocatalyst were responsible for RhB and BG degradation.