Surface charge transfer properties of high-performance Ag-decorated ZnO photocatalysts

Silver-decorated ZnO (Ag/ZnO) chain-like nanoparticle aggregates were prepared by a facile nonaqueous sol–gel method. The influence of Ag decoration on the surface photo-induced charge transfer behaviour of ZnO was investigated by means of surface photovoltage spectroscopy, electric field-induced surface photovoltage spectroscopy and transient photovoltage techniques. The photovoltage spectra revealed that an electronic interaction between Ag and ZnO formed. Ag acted as electron acceptors and effectively inhibited the charge recombination in ZnO with UV light illumination, while under the illumination of visible light a redshift was observed due to the appearance of a plasmon-induced band resulting from the formation of Ag nanoparticle clusters. These were responsible for the significant enhancement in the photocatalytic activity of the Ag/ZnO sample. The results also suggested that the high-performance visible light photocatalytic activity could be manipulated by external biases.