A Review on Chemiresistive Hybrid Zinc Oxide and Nanocomposites for Gas Sensing

Chemiresistors have been widely employed in monitoring toxic fumes, gases, and environmental pollutants. Among a plethora of metal oxide semiconductors (MOX) used for preparing chemiresistors, zinc oxide is the topmost candidate. ZnO-based gas sensors are cost-effective, nontoxic, stable, and easily prepared by wet chemical facile approaches. ZnO nanostructures are the most promising candidates for leakage detection of toxic gases with reliable performance. In this regard, several investigations have been carried out to increase sensor response at room temperature (RT). Current advances in ZnO nanostructures-based thin films are the subject of this review paper. The review begins with a basic survey of ZnO thin films for gas sensors focusing on how the structure and properties of ZnO affect the gas response mechanisms, various factors and processing methods of ZnO nanostructures, and possible ways to enhance the gas response characteristics of ZnO-based sensors.