Air Pollution Monitoring Using Near Room Temperature Resistive Gas Sensors: A Review

The growth of industries and other human activities have led to ever increasing amounts of pollutants in both outdoor and indoor spaces. These pollutants have hazardous effects on humans and the wider ecology. Hence, air quality monitoring (AQM) is essential and involves the robust monitoring of various toxic gases and volatile organic compounds (VOCs)-in case, the concentration of any pollutant exceeds the safe limit in a given location. This paper describes the different sources of indoor and outdoor pollutants, reviews the current status of gas sensors, and discusses the role of new two dimensional (2-D) materials in detecting these hazardous gases at low power, i.e., close to the ambient temperature. Here, we review different synthesis techniques of 2-D materials and discuss the sensing performances of pristine and functionalized nanomaterials for some of the important pollutants such as NOx, NH3, SOx, CO, formaldehyde, toluene, and so on. The review concludeswith some proposedmethods to help in reducing air pollution today.