Palladium and silver nanoparticles embedded on zinc oxide nanostars for photocatalytic degradation of pesticides and herbicides

Abstract In this study, we demonstrated the efficient charge separation and migration at zinc oxide nanostars (ZnONSt) via conjugation with noble metal nanoparticle (MNP = Ag, Pd) and its application in degradation of carcinogenic pesticide [methyl parathion (MP)] and herbicides [pendimethalin (PDM), trifluralin (TFL)]. A well dispersed noble MNP incorporation on ZnONSt surface has been carried out by microwave-hydrothermal (MW-HT) method. The related phase constitution, the presence of functional groups, optical properties, elemental composition, surface area, and surface morphology were evaluated using various analytical techniques. The XRD patterns and FE-SEM/TEM micrographs revealed the ZnONSt had hexagonal wurtzite phase with a star-like morphology. The Ag@ZnONSt and Pd@ZnONSt exhibited excellent photocatalytic activity towards the photodegradation of pesticide, and herbicides under irradiation of visible light (VL). Pd and Ag nanoparticles act as electron sink and thus facilitate the interfacial charge transfer process by suppression of charge recombination rate. In particular, Pd@ZnONSt nanocomposite showed the better performance than the ZnONSt with different morphology and other commercial photocatalysts. A plausible mechanism for the enhanced photocatalytic activity by Pd@ZnONSt was proposed. Our results might open up a promising way to develop novel and highly efficient photocatalysts based on ZnONSt-related heterostructure.