Recent Developments on Metal Oxide - Based Gas Sensors for Environmental Pollution Control

Many toxic gases are released or emitted in the environment and exist in the atmosphere such as hydrocarbons (HCs), nitrogen oxides (NOx), carbon monoxide (CO), carbon dioxide (CO2), sulfur dioxide (SO2), ammonia (NH3), hydrogen sulphide (H2S), and volatile organic compounds (VOCs) even in small concentrations can cause various health problems and poisoning. Therefore, sensitive technological devices are necessary to detect the presence of toxic and dangerous gases in the environment. Nanotechnology-based on metal oxide gas sensors can overcome this problem. Semiconductor metal oxide nanostructures have proven to be highly suitable for applications in sensors due to their high sensitivity, chemical, and thermal stability, and large surface-to-volume ratio. Apart from sensitivity, selectivity, stability, and speed parameters, recovery time, response time and power consumption are also other which determines sensor device. Metal oxide-based gas sensors work based on the change in electrical conductivity due to charge transfer between surface complexes and interacting molecules. This paper will discuss recently developed metal-oxide based sensors for the detection of toxic gases present in the environment.