Enhanced NO2 sensing properties of Pt/WO3 films grown by glancing angle deposition

Abstract In this work, WO3 films were synthesized by glancing angle deposition (GLAD) and conventional planar deposition respectively. By depositing Pt on WO3 by GLAD, the NO2 sensitivity of WO3 films were significantly improved. The structural characteristics and NO2 sensing properties of the films were investigated in order to establish the enhancement mechanism. The results show WO3 films prepared by GLAD have porous nanorod-like structure, and isolated Pt clusters are distributed on WO3. The nanostructured Pt/WO3 films show high sensitivity to NO2 at 150 °C, detecting as low as 80 ppb NO2 with a response of 1.23. Meanwhile, the films also exhibit high NO2 selectivity against NH3, CO, acetone and ethanol. The excellent NO2 sensing properties of the Pt/WO3 films can be explained due to large specific surface area of nanorod-like WO3, catalysis of Pt and Schottky barriers at interfaces. The reliable Pt/WO3 nanostructure prepared by GLAD could be potentially applied in low-temperature, highly sensitive NO2 sensor for micro-electro-mechanical system (MEMS).