The synthesis of a Ag-ZnO nanohybrid with plasmonic photocatalytic activity under visible-light irradiation: the relationship between tunable optical absorption, defect chemistry and photocatalytic activity

In this work, a visible-light-driven plasmonic Ag-ZnO nanohybrid photocatalyst was prepared by a one-pot approach with the aim of tailoring its structural, electronic and photocatalytic properties. The as-prepared samples were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-vis optical diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and electron spin resonance (ESR) spectroscopy. The effects of silver loading on the electronic structure and photodegradation of a rhodamine B dye solution were investigated experimentally and theoretically. It was found that the Ag-ZnO nanohybrid showed an enhanced photocatalytic activity for the degradation of the rhodamine B dye solution under visible-light irradiation and the photocatalytic performance was optimized at an Ag/Zn molar ratio of 0.05. The enhancement of the photocatalytic activity was attributed to the effective charge transfer from the plasmon-excited Ag nanoparticles to ZnO, which suppresses the charge recombination during the photocatalytic process. Optionally, the effective recycling of the photocatalyst was achieved by visible light illumination, free of secondary environmental contamination. This work may provide a new insight into the design and preparation of advanced ZnO-based visible-light photocatalytic materials.