Electron beam irradiation treatment of Ag/Bi2WO6/CdWO4 heterogeneous material with enhanced photocatalytic activity

Abstract

An efficient ternary heterostructure material Ag/Bi₂WO₆/CdWO₄ was prepared via a facile hydrothermal route. The in situ loading precisely regulated the distribution of silver nanoparticles on the heterojunction surface. Besides, electron beam irradiation was used for artificially creating interface defects in the material, so the specific surface area of the material was increased. The introduction of defects was conducive for the migration of catalytically active substances towards the surface of the material. Under visible light irradiation, the degradation efficiency of the heterostructure material was improved significantly. Within 20 min, the removal efficiency of the treated material for carmine could reach about 100% (50 mL, 50 mg L⁻¹), while that for hexavalent chromium (Cr⁶⁺), it could reach about 100% (50 mL, 10 mg L⁻¹) within 90 min. In addition, the results showed that 4% Ag load rate had the best improvement on the photocatalytic performance of the ternary heterostructure material, irrespective of the degradation process of carmine, Cr⁶⁺ or rhodamine B (RhB). Optimum amount of supported in situ nano-silver induced resonance of the plasma on the catalytic interface and synergized with Bi³⁺ to improve the catalytic efficiency. PL, DRS and XPS results proved that the ternary heterostructure could effectively inhibit the rapid recombination of electron hole pairs of Ag/Bi₂WO₆/CdWO₄. As for the role of electron beam irradiation, it could improve the content of free hydroxyl groups on the material surface and enhance the catalytic capacity of the Ag/Bi₂WO₆/CdWO₄ heterogeneous material. A feasible reaction pathway and photocatalytic mechanism for the degradation of carmine was investigated by gas chromatography-tandem mass spectrometry (GC-MS), and the main role of ˙OH in the catalytic process was obtained by using different scavengers.