One-step microwave synthesis of Ag/ZnO microrods as photocatalysts

Abstract

Ag/ZnO microrods were synthesized by a simple and convenient microwave route using zinc acetate, silver nitrate and methenamine as raw materials. Phase structure, morphology, elementary composition, optical property of the products were characterized by X-ray diffraction, scanning electron microscope, X-ray photoelectron spectroscopy and UV-3600 spectrophotometer, respectively. Photocatalytic performance of Ag/ZnO was evaluated by studying the degradation of methylene blue (MB) dye in aqueous solution under UV-Visible light irradiation. The results show that well crystallized dumbbell shaped Ag/ZnO microrods were achieved under microwave radiation power of 240 W for 15 min. Ag/ZnO photocatalysts exhibited an enhanced photocatalytic performance as compared to monolithic ZnO. The Ag/ZnO photocatalyst with 3.0 mol% silver exhibited obviously the best photocatalytic activity among the Ag doped samples under degradation condition. 100.0% of MB was degraded after 60 min of UV-Visible light irradiation in presence of 30 mg 3.0 mol% Ag/ZnO. The apparent reaction rate constant (k, 0.0865 min⁻¹) of 3.0 mol% Ag/ZnO is 4.1 times higher than that of monolithic ZnO (k, 0.02107 min⁻¹). The formation mechanism of dumbbell shaped Ag/ZnO during the microwave reaction process was also discussed.

Keywords:

• Ag/ZnO microrods
• microwave
• photocatalytic activity