Effect of vacuum annealing on solar light response and photocatalytic performance of Ag nanoparticle-modified ZnO thin films

Ag–ZnO thin films were prepared by a two-step method and then annealed in a vacuum atmosphere at different temperature. It could be seen from the scanning electron microscopy images that the ZnO nanorods collapsed rapidly for the sample annealed at 400 °C (Ag–ZnO-400) and the average diameter of Ag nanoparticles increases with the increasing of annealing temperature. Compared to Ag–ZnO, the Ag–ZnO-400 presents the higher surface plasmon resonance absorbance peak, which was attributed to the increasing of the average diameter of silver nanoparticles. The transient photocurrent curves exhibited that the photocurrent density of Ag–ZnO-400 (~ 0.165 mA/cm−2) was twenty time larger than that of the Ag–ZnO (~ 0.008 mA/cm−2). The photocatalytic degradation efficiency of Ag–ZnO-400 catalysts for the methyl orange in aqueous solutions is over 63%.