Ag/ZnO flower heterostructures as a visible-light driven photocatalyst via surface plasmon resonance

Visible-light driven photocatalyst, Ag/ZnO flower (ZnO Fl) heterostructures, was prepared on indium doped tin oxide (ITO) glass via a simple photoreduction method without surfactants. The samples are characterized by X-ray diffraction, scan electron microscopy, X-ray photoelectron spectroscopy, UV–vis spectroscopy, photoluminescence spectra and photocurrent response. The results show that ZnO FRs are wurtzite phase with single crystalline grown along the [0   0   1] direction and Ag nanoparticles (NPs) located on the surface are metallic. The binding energy of Ag 3d for the Ag/ZnO Fls sample shifts remarkably to the lower binding energy compared with the corresponding value of pure metallic Ag attribute to the interaction between Ag and ZnO Fls. Ag/ZnO Fl heterostructures exhibit higher visible-light driven photocatalytic activity. It is suggested that photo-induced electrons are generated from Ag due to surface plasmon resonance, and transfer from Ag to ZnO Fls. Then the electrons interact with adsorbed oxygen, finally forming hydroxyl radicals ( OH), and the visible-light driven photocatalytic efficiency is enhanced. The proposed mechanism is further confirmed by the photoluminescence and transient photocurrent response. Additionally, the as-prepared Ag/ZnO Fls/ITO as a convenient photocatalytic device can be recycled without centrifugation.