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.