Enhanced ammonia sensing properties using Au decorated ZnO nanorods

Abstract

Nanostructured Au-ZnO sensor systems have recently attracted attention for improving sensing behavior towards ethanol, acetone, hydrogen, CO, but rarely towards ammonia. In this report, an enhanced sensing response towards ammonia at near room temperatures using Au decorated ZnO nanorods (NR) is reported in comparison to pristine ZnO NR of hexagonal wurtzite structure. A facile two step synthesis method is adopted involving hydrothermal synthesis for the preparation of high aspect ratio ZnO NR of 40 nm diameter and 100 nm length followed by chemical growth methods for nanoparticle Au decoration of 5 nm average particle size. UV-Visible Diffuse Reflectance Spectroscopy confirms presence of Au nanoparticles along with ZnO NR with characteristic surface plasmon resonance and ZnO exciton peak. Gas sensing studies revealed that the Au-decorated ZnO NR can detect ammonia even at 50°C and shows highest response at 100°C than pristine ZnO NR which shows a response maximum at 300°C.