Recent progress in Nanostructured Metal Oxides based NO2 gas sensing in India

The metal oxides are considered as an outstanding semiconductor material to sense several toxicants from the environment. In particular, the nanostructure containing rod, wire, and tube-like morphology of metal oxides were widely utilized to fabricate effective gas sensors worldwide. Out of number of toxicant, nitrogen dioxide (NO2) is one of the highly reactive gas, results from the burning of fuel from vehicles, power plants, and off-road equipment.The exposures to NO2 may giverise to the development of the respiratory diseases and leads to the death. Therefore, the efficient detection of NO2 gas is the urgent need of recent era. More than 5000 research articles were published on the NO2 gas sensing worldwide. The researchers from India is also contributed a lot to detect the NO2 gas via nanostructured metal oxides powder and thin films. The aim of the present article is to explore the recent advances of NO2 gas sensors based on metal oxide nanomaterials within the country. The review begins with the general introduction of metal oxide, gas sensorand NO2 gas sensor and followed by the broadly discussion of major research groups working in India and their finding in the fieldof nanostructured metal oxide for the fabrication of NO2 gas sensors. Moreover, various factors likegas concentrations, working temperature, morphologies, sensor response, selectivity, etc. of metal oxides were discussed in the present report. The report concludes with the future directions and opportunities in the field of detection of NO2 gas in India and world.