Ultra-low NO2 detection by gamma WO3 synthesized by Reactive Spray Deposition Technology

A porous tungsten oxide (WO3) NO2 sensor was developed by a one-step flame based process called Reactive Spray Deposition Technology (RSDT). This nano-crystalline WO3 film was deposited directly on gold interdigitated electrodes. The sensing characteristics of this NO2 sensor was measured at the parts per million (ppm) level, (0.17-5 ppm in air) at 300 degrees C. The sensors showed a relatively fast response time (similar to 7s) and recovery time (similar to 5 min), respectively. The stability of the sensor was evaluated for 300 h in 0.5 ppm NO2 at 300 degrees C in (2000 response-recovery cycles). The sensor was stable up to 6 days (similar to 150 h) of continuous operation and degraded between 150-300 h. The morphology and surface properties of the WO3 film were investigated with XRD, Raman spectroscopy, BET, SEM, TEM, and HRTEM. (C) 2016 Elsevier B.V. All rights reserved.