Flower-like Ag2WO4/CeO2 heterojunctions with oxygen vacancies and expedited charge carrier separation boost the photocatalytic degradation of dyes and drugs

Abstract

Charge carrier separation is a very important factor in photocatalysis, and it may be achieved through a variety of paths including the construction of heterojunctions and the formation of surface defects. Herein, we demonstrate the construction of flower-like Ag₂WO₄/CeO₂ heterojunctions (namely ACs) by in situ deposition of Ag₂WO₄ on the surface of flower-like CeO₂ with oxygen defects. The ACs with 2.3%, 3.8%, and 5.3% Ag₂WO₄ are defined as AC-1, AC-2, and AC-3, respectively, and we compare their photocatalytic removal efficiencies. Under visible light, AC-2 exhibits the highest photocatalytic removal efficiency toward cationic dye RhB and tetracycline (TC). The K value of AC-2 toward RhB degradation is determined to be 0.059 min⁻¹, which is 7.56 and 8.94-fold higher than those of Ag₂WO₄ (0.0078 min⁻¹) and CeO₂ (0.0066 min⁻¹), respectively. Moreover, the K value of AC-2 toward TC degradation (0.021 min⁻¹) is 4.04 and 5.68-fold higher than those of Ag₂WO₄ (0.0052 min⁻¹) and CeO₂ (0.0037 min⁻¹), respectively. Our results clearly demonstrate that the introduction of Ag₂WO₄ particles stimulates the formation of surface defects of CeO₂, improves the visible light absorption, accelerates the charge carrier separation, and consequently boosts the photocatalytic degradation of dyes and drugs.