Low-temperature NO2 sensor based on γ-In2Se3/In2O3 nanoflower heterojunction

The γ-In 2 Se 3 /In 2 O 3 nanoflower-like heterojunctions were synthesized by solvothermal treatment followed by thermal oxidation in Air. The nanoflower-like γ-In 2 Se 3 /In 2 O 3 -based chemiresistive-type sensor showed a significantly enhanced response to NO 2 at an operating temperature of 170°C. The sensor achieves a response of 2.69–0.2 ppm NO 2 at 170°C. The sensor exhibits remarkable selectivity to several possible interferents such as carbon monoxide , ammonia, formaldehyde, acetone, methanol, and toluene, and good stability at 170°C. The nanoflower structure increases the specific surface area and introduces more active sites, which improves the sensitivity of the sensor to NO 2 . The heterojunction formed between γ-In 2 Se 3 and In 2 O 3 improves the charge carrier transfer between NO 2 gas molecules and sensing materials, thereby increasing the response of the sensor to NO 2 . Density functional theory was used to elucidate this sensing mechanism, and it was found that improved sensing performance is mainly due to heterojunction formation , which increases the adsorption energy of nitrogen dioxide molecules on a sensing material surface and facilitates charge transfer between molecules.