Narrow Results

Water pollution caused by intensive use of organic dyes has become an increasingly serious problem recently. Green and efficient processes are desperately needed to remove persistent organic pollutants from waste waters. Herein, Ag nanoparticles loaded ZnO hollow microspheres were synthesized through a simple solvothermal method and used as a photocatalyst for dye degradation. The calculated band gap of Ag/ZnO — 5% (2.97eV) is much narrower than that of pure ZnO (3.37eV). The obtained Ag/ZnO samples show a remarkable photocatalytic activity in photodegradation of Rhodamine B (RhB) under simulated sunlight irradiation. The degradation efficiency of RhB for Ag/ZnO — 5% is 98.8% after 100min irradiation while only 52.8% degradation rate is obtained over pure ZnO. The enhancement is attributed to the exposed active ZnO (001) plane and the surface plasmon resonance (SPR) effect of Ag nanoparticles that promote the separation of photogeneated electrons and holes.

Zinc oxide (ZnO) has demonstrated significant potential as a photocatalyst for the wastewater treatment. However, its wide bandgap leads to inefficient light utilization and rapid carrier recombination, which inhibits its photocatalytic activity. To overcome these limitations, we employed a hydrothermal method to synthesize Ag/ZnO composite microspheres with different concentrations of Ag nanoparticles. By utilizing Ag complexed with ZnO, the Ag/ZnO composite photocatalysts were made to have a narrower bandgap and a broadened light response range, as well as the red-shift phenomenon at the absorption edge. In addition, Ag nanoparticles can act as electron traps to efficiently capture electrons and minimize the recombination of photoexcited carriers for improved photocatalytic performance. Compared with other concentrations of ZnO microspheres and pure ZnO microspheres, the 5% Ag/ZnO composite microspheres exhibited excellent degradation performance when exposed to a xenon lamp, with 90.1% degradation of rhodamine B (RhB) solution in 100min. Incorporating trapping agents in experimental studies has indicated that the RhB degradation process is significantly influenced by •O${}_2^{-}$, while the impact of •OH and h${}^{+}$ were relatively weak. Thus, Ag/ZnO nanocomposites hold great promise as materials for use in wastewater treatment.