Chemically Processed Metal Oxides for Sensing Application: Heterojunction Room Temperature LPG Sensor

Sensors to detect the leakage of hazardous gases are indispensable to avoid accidental problems for human health. Sensors become part of industrial application and day-to-day life. Design and development of gas sensor need wide range of materials where the use of semiconducting metal oxide is on prime priority owing to its inherent exceptional chemical and physical properties and simple route of preparation through less expensive methods. Liquefied petroleum gas (LPG) is injurious to human health due to its explosive and inflammable properties. The extensive use of LPG generated a room for encroachment of sensitive and cost-effective gas sensors which can sense leakage before any severe calamities can occur. Research on sensing materials are currently aimed extensively on nanostructured materials of metal oxide semiconductor with numerous surface architectures in nano forms having their sizes in nano regime, namely, quantum dots, nanobelts, nanotubes, nanoparticles, nanowires, and nanorods due to abrupt change in conductivity under gas environment. High surface-to-volume ratios in addition to huge quantity of active sites associated with nanostructured architecture help to achieve maximum sensitivity when exposed to gas. Present chapter deals with chemically processed heterojunction-based metal oxide material towards room temperature LPG sensors with primary emphasis given on fundamental properties, basic mechanism with design and operation, recent progress, and future trends. Particularly, the chapter points out the state of the art towards the advancement in LPG sensors centered on semiconducting metal oxides with heterostructure properties. Furthermore, the comprehensive illustrations on heterojunction gas sensors based on metal oxides open up new directions for further exploration on room temperature LPG sensors.