Design and Fabrication of Wo3 Nanostructures for Gas Sensing Application

Abstract

Over the past few decades, environmental pollution has been increasingly impacted by newlinethe release of various toxic gases, including sulphur dioxide (SO2), ammonia (NH3), nitrogen newlinedioxide (NO2), nitrous oxide (N2O), and hydrogen sulphide (H2S). Among these, nitrogen newlinedioxide (NO2) is recognized as one of the most hazardous pollutants in the current newlineenvironmental context. Significant amounts of NO2 emissions originate from fossil fuel newlinecombustion and nuclear power plants. Even exposure to low concentrations (in parts per newlinemillion) of NO2 can pose serious health risks and environmental threats. To address this issue, newlinesemiconductor-based transition metal oxides have attracted considerable interest for gas newlinesensing applications due to their nanostructure driven adsorption and catalytic properties. newlineWithin the family of metal oxides, tungsten trioxide (WO3) nanostructured thin films have newlineshown excellent sensitivity toward toxic gases such as CO2, NO2, SO2, NH3 and H2S. Owing newlineto this, WO3 based nanostructures are considered promising candidates for practical and newlineefficient gas sensor devices. Despite the potential of WO3 based gas sensors, their practical newlineapplication has been hindered by limited sensitivity and poor stability under ambient newlineconditions, posing challenges for large-scale commercialization. To address these newlineshortcomings, various strategies have been explored in recent years. In this thesis, doping newlineWO3 nanostructures with transition metals (Al, Co, Bi) and decorating with noble metals (Ag) newlinehave been adopted as effective methods to enhance sensor performance. Furthermore, a newlinecomprehensive investigation has been carried out on the structural, morphological, chemical, newlinesurface, and gas sensing characteristics of the synthesized materials newline