The photocatalytic enhancement effect of the one-pot synthesis of Au-Ag nanoparticles on ZnO nanorods prepared on glass substrates

Abstract

The deposition of gold-silver (Au-Ag) nanoparticles on zinc oxide (ZnO) nanorods was successfully done via a one-pot hydrothermal method. The X-ray diffraction (XRD) spectra and Field Emission Scanning Electron Microscopy (FESEM) images showed that the ZnO nanorods had a hexagonal wurtzite crystal structure and the Au-Ag nanoparticles were face-center-cubic crystal spherical-shaped with a diameter ranging from 10 nm to 100 nm. The localized surface plasmon resonance effect of Au-Ag nanoparticles may induce the enhancement absorption in a visible region and also slightly decrease the band gap energy of ZnO nanorods. The room temperature photoluminescence spectra showed that intensity decreased in the range of 370–700 nm due to the decrease in the exciton recombination effect of the ZnO nanorods after deposition of the Au-Ag nanoparticles. The presence of Au-Ag nanoparticles also slightly enhanced the photodegradation rate of methyl blue; this may be because the photoexcited electrons of ZnO were trapped in the Au-Ag nanoparticles, which hinders the recombination of the charge carriers in ZnO and enhances the generation of free radicals for degradation of methyl blue at pH of 5.0 under ultraviolet (UV)-light irradiation.