Study on the photogenerated charge transfer and photoelectrocatalytic performance of Ag/ZnO nanorod arrays under the irradiation of simulated sun light

Abstract

Ag/ZnO nanorod arrays with enhanced photoelectric response properties under simulated sun light were synthesized by a facile two-step process and characterized by x-ray powder diffraction (XRD), UV–vis diffuse reflectance spectra (UV–vis DRS) and the field emission scanning electron microscopy (FESEM). The photoelectrocatalytic (PEC) activities of the catalysts were evaluated by degrading efficiency of methylene blue (MB) dye under simulated sun light. The MB removal rate can reach 85% after the irradiation of simulated sunlight for 30 min. Surface photovoltage (SPV) measurements and transient photovoltage (TPV) spectra demonstrated that Ag loading improved the utilization of the visible spectral absorption of ZnO nanorod arrays, as well as their separation efficiency of photogenerated electron–hole pairs, which may be due to the capture effect of Ag nanoparticles for free electrons under the irradiation of simulated sunlight. The photoelectrochemical investigations indicated that the Ag/ZnO nanorod arrays showed enhanced photocurrent generation efficiency, and had a more effective interface charge transfer path. The fast PEC degradation of MB is ascribed to the highly ordered nanorod architecture, the large effective mass of the photogenerated holes on the surface of ZnO induced by Ag nanoparticles loading, as well as the effective transport of photogenerated charge carriers under the effect of external electric field.