12. II–VI Semiconductor-Based Optical Gas Sensors

Optical gas sensors are the one which utilize optical properties of materials that responds by the infusion of gas in the environment. Optical gas sensors play an important role in detecting, controlling and reducing air pollution. Also, these optical-based gas sensors are used to prevent workers from fire and explosions. II–VI semiconductors are the most promising ones for optical gas sensors owing to their band gap, size and shape-dependent optical properties, facile synthesis methods and ability to form colloidal solution of nanostructures. This chapter discusses about the various optical methods viz. photoluminescence (PL), fluorescence (FL), fibre optics, surface plasmon resonance (SPR), etc., based gas sensors utilizing different morphologies like 1D, quantum dots, core-shell, embedded in matrix, etc. The introduction is about the need for optical gas sensors, the suitability of II–VI semiconductors, and the parameters used for optical gas sensors. The next section deals with different PL-based gas sensors with different morphologies of II–VI semiconductor materials followed by FL-based gas sensors. Some other optical methods like chemiluminescence, cataluminescence and optical absorption are mentioned in the next section. Further, two sections deal with SPR-based and fibre optics-based gas sensors, respectively, followed by a concrete conclusion that explains the challenges of II–VI materials-based optical gas sensors.