Natural sunlight driven photocatalytic performance of Ag/ZnO nanocrystals

Abstract

Herein, spherical-shaped ZnO nanoparticles of an average size of about 10 nm were successfully synthesized through a soft chemical approach. We further prepared the Ag/ZnO nanocrystals by varying the loaded amounts of metallic silver nanoparticles (1, 3, and 5 wt%) without using any reducing and stabilizing agent. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analysis confirmed the transformation of Ag ions into metallic Ag and the interaction between Ag and ZnO nanoparticles. High resolution-transmission electron microscopy (HR-TEM) images revealed that Ag nanoparticles of an average size of about 4.6 nm are present on the surface of spherical ZnO nanoparticles. UV-visible absorption spectra showed that the appropriate amount of Ag loading with ZnO shifted the band gap from UV to the visible region. Photoluminescence spectrum reveals the inclusion of Ag in ZnO and minimizes the recombination of electron-hole pairs. These synthesized Ag/ZnO nanocrystals were investigated for its potential applications in photocatalytic degradation of methylene blue dye under UV and sunlight irradiation and compared their efficiency with pure ZnO. Interestingly, it is seen that ZnO nanocrystals that are UV active become visible active when loaded with 1 and 5 wt% of metallic Ag. ZnO loaded with 1 wt% of metallic Ag completely degraded the methylene blue within 3 h under natural sunlight. Under UV light, 3 wt% of Ag in ZnO exhibits higher photocatalytic performance than the others. Thus, incorporating metallic Ag in ZnO nanoparticles shows excellent photocatalyst performance and recycling capability. Furthermore, the participation of different reactive species in the photocatalysis degradation mechanism was studied using four scavengers and the results indicate that superoxide and singlet oxygen are the dominant reactive species. We report heterostructure of Ag/ZnO nanocrystals and explored their efficiency for photocatalytic degradation of dye under visible light irradiation. • Synthesis of Ag/ZnO nanocrystals without any reducing and stabilizing agent. • Transformation of band gap from UV to Visible by incorporation of appropriate amount of Ag in ZnO. • Excellent photocatalytic performance and recycling capability for degradation of dye under UV and natural sunlight. • These nanocatalysts can be for further use for inhibition of bacteria pathogens.