Ultra-high sensitive and ultra-low NO 2 detection at low-temperature based on ultrathin In 2 O 3 nanosheets

In this study, the high oxygen vacancy-rich ultrathin indium oxide (In 2 O 3 ) nanosheets are synthesized by low-cost and environmental-friendly solvothermal method. The gas sensing properties of In 2 O 3 nanosheets to low concentration of nitrogen dioxide (NO 2 ) (concentration in 5 ppb to 5 ppm) at 50 °C are investigated. All In 2 O 3 samples are successfully characterized using various techniques to obtain the information related to phase, morphological, oxygen vacancies, and surface area, etc. It is observed that among all the samples, the In 2 O 3 -350 exhibited benchmarked response of around 3223 at 2 ppm NO 2 gas, with theoretical detection limit down to ppb level. The sensor has shown superior sensing characteristics, such as wide sensing bandwidth, excellent selectivity, high long-term stability, and good repeatability. It is considered that the high oxygen deficiency present on In 2 O 3 nanosheets acts as favorable reaction sites for such remarkable sensing performance, and therefore, these improved gas-sensing properties make the In 2 O 3 nanosheets suitable to detect NO 2 at low-temperature.