W-doped indium oxide synthetized via hydrothermal route as an ozone sensitive material at low temperature

Traffic emissions and industrial pollution release harmful levels of ozone (O3), nitrogen dioxide (NO2), volatile organic compounds (VOCs) and ultrafine particulate matter (PM) into ambient air, resulting in higher incidence of morbidity and mortality in respiratory diseases [1]. Among tropospheric pollutants, monitoring the concentration of O3 appears crucial due to its toxicity. In 2015, EPA (United States Environmental Protection Agency) strengthened the National Ambient Air Quality Standards (NAAQS) for ground-level O3 not to exceed 70 ppb to improve public health protection [2]. This work introduces sensitive MOS (metal oxide semiconductors) sensors based on n-type indium oxide and 2.5 wt.% tungsten-doped indium oxide thick film to monitor O3 amounts at sub-ppm level at low temperatures. Pristine In2O3 hydrotermally sinthetized constitutes a valuable platform for the development of sensitive O3 detectors. In this work, it was doped with WO3 by impregnation route to increase its sensitivity towards ozone. The cross-sensitivity towards humidity, NO2, N2O, NH3, CH4 and CO2 was also investigated.