Construction of hierarchical Ag@TiO2@ZnO nanowires with high photocatalytic activity

Abstract

Noble metal loading and semiconductor compositing are two effective techniques to improve the photocatalytic activity of semiconductor photocatalysts. These two tactics are combined herein to achieve hierarchical Ag@TiO₂@ZnO nanowires, which consist of ZnO nanorods growing radially from Ag nanowires with the help of a compact TiO₂ intermediate layer. The Ag@TiO₂@ZnO nanowires consisted of 4.3 wt% Ag, 16.7 wt% TiO₂ and 79.0 wt% ZnO. When utilized to assist photodegradation of phenol in water under UV light illumination, the nanowires exhibited a reaction rate constant 1.8 times that of commercial Degussa P25 TiO₂ nanoparticles and 3.8 times that of commercial ZnO nanoparticles. The excellent photocatalytic activity can be contributed to the enhanced light adsorption and charge separations arising from both Ag/TiO₂ Schottky barriers and TiO₂/ZnO heterojunctions.