(22f) Microwave-Assisted Synthesis of Extra-Fine Ag@Agi Photocatalyst With High Activity Under Visible Light Irradiation

In this study, a novel extra-fine plasmonic photocatalyst, Ag@AgI, was synthesized via microwave-assisted irradiation in nonaqueous media. The obtained Ag@AgI nanoparticles (NPs) were characterized by means of X-ray diffraction, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy and UV-visible diffuse reflectance spectroscopy. The size and shape of the Ag@AgI photocatalysts could be controlled by tuning the microwave irradiation time and the concentration of polyvinylpyrrolidone (PVP) in the reaction solution, and the properties of the composites and the effects of the reaction parameters on the photocatalyst were studied. The composites were found to be highly affected by the microwave irradiation time and the concentrations of PVP. The as-prepared Ag@AgI had a minimum diameter of about 100 nm with 0.3 mmol PVP in 140 ⁰C under microwave irradiation for 5 min. The as-prepared plasmonic photocatalysts Ag@AgI showed excellent visible light photocatalytic performance and good durability for the degradation of Rhodamine B (RhB), with almost 97.40% RhB degraded in 20 min under the optimized conditions. The highly efficient degradation of RhB and good stability was closely related to the photoexcited AgI and plasmon excited Ag NPs anchored on its surface. The detection of reactive species by radical scavengers indicated that ·OH and the positive hole (h⁺) or the surface-adsorbed ·OH were the main reactive species for the degradation of RhB under visible light irradiation. In addition, the mechanism of the plasmonic photocatalytic process was proposed. Due to the high activity and excellent durability for visible light induced degradation, the novel Ag@AgI prepared provides interesting potential for use as visible light active photocatalysts in applications for the photodegradation of organic pollutants in wastewater.