Preparation of Silver and Copper Co-impregnated Nano-ZnO Immobilized on Mesoporous SiO2 and its Photocatalytic Performance

Abstract

To improve light usage, Ag and Cu were co-impregnated with nano-ZnO, and the mesoporous silica gel (meso-SiO2) was chosen as the carrier. The sol-gel method was used to successfully construct a composite photocatalyst with 3 percent Ag/0.1 percent Cu/nano-ZnO/meso-SiO2. For the evaluation of the photocatalytic activity of the as-prepared catalysts, Reactive Black 5 was used as a simulated organic pollutant in aqueous. The results revealed that uniform spherical nano-ZnO particles with a diameter of 10 nm were attached to the surface and mesopore of meso-SiO2. The average pore width and specific surface area of this composite were 7.06 nm and 305 m2.g-1, respectively. The optimal amount of loaded Ag and Cu were 3% and 0.1%, respectively, which resulted in around 100% removal of Reactive Black 5 after 280 min UV-light irradiation. The degradation process followed pseudo-first-order kinetics. Ag and Cu-loaded nano-ZnO/SiO2 could be advantageous for suppressing the recombination of photo-generated holes and electrons, thus improving the degradation efficiency. The constant of degradation rate and adsorption equilibrium of 3%Ag/0.1%Cu/nano-ZnO/meso-SiO2 were 0.049 min–1 and 2.14 L.g-1, respectively. After three reuses, the Ag/Cu/ZnO/meso-SiO2 photocatalyst remained very stable during the photocatalytic process with no loss of photocatalytic activity. According to the GC-MS results, a probable degradation mechanism was estimated.