Tungsten Oxide Nanocomposites as High-Performance Gas Sensors: Factors Influencing the Sensor Performance

Abstract

Nowadays, numerous types of gas sensors are available in the market. Amongst them semiconducting gas sensors are more favourable due to its cost-effectiveness, high electron mobility, electrical conductivity, thermal, chemical, and mechanical stability. Moreover they possess better sensitivity towards various oxidizing and reducing gases. This chapter describes synthesis, physico-chemical properties, gas sensing performance and the factors influencing the sensing performance of nanostructured tungsten oxide nanocomposites. Influence of (i) noble metal loading (Ruthenium), (ii) structure-assisting agent (glycine), and (iii) graphene oxide loading (RGO) is discussed intensively. The range of reduced and oxidizing gases such as acetone, ethanol, propanol, ammonia, NOX, and H2S is scanned for better selectivity. Depending upon the type of additives used to fabricate the WO3 nanocomposites, the aforementioned gases showed variant selectivity. For example, glycine-modified WO3 showed decent selectivity towards acetone, whereas Ru and RGO loading enhanced the H2S sensing performance. The sensor developed with Ru-loaded WO3 nanocomposite showed a selective response of 83.87% for barely 1 ppm H2S. Further, the single and unique strategy of developing microporous WO3 with different morphologies spanning over nano-to-micro, using glycine as a structure-assisting agent, showed 83.87% sensing towards acetone at 10 ppm concentration. The morphological correlation with the sensitivity is described. Sensor derived from RGO-loaded WO3 nanocomposite showed a selective response of 64.2% for barely 1 ppm H2S. All the developed sensor materials are compared to their gas sensing performance and discussed.