SnO-Sn 3 O 4 heterostructural gas sensor with high response and selectivity to parts-per-billion-level NO 2 at low operating temperature.

Considering the harmfulness of nitrogen dioxide (NO 2 ), it is important to develop NO 2 sensors with high responses and low limits of detection. In this study, we synthesize a novel SnO-Sn 3 O 4 heterostructure through a one-step solvothermal method, which is used for the first time as an NO 2 sensor. The material exhibits three-dimensional flower-like microparticles assembled by two-dimensional nanosheets, in situ -formed SnO-Sn 3 O 4 heterostructures, and large specific surface area. Gas sensing measurements show that the responses of the SnO-Sn 3 O 4 heterostructure to 500 ppb NO 2 are as high as 657.4 and 63.4 while its limits of detection are as low as 2.5 and 10 parts per billion at 75 °C and ambient temperature, respectively. In addition, the SnO-Sn 3 O 4 heterostructure has an excellent selectivity to NO 2 , even if exposed to mixture gases containing interferential part with high concentration. The superior sensing properties can be attributed to the in situ formation of SnO-Sn 3 O 4 p-n heterojunctions and large specific surface area. Therefore, the SnO-Sn 3 O 4 heterostructure having excellent NO 2 sensing performances is very promising for applications as an NO 2 sensor or alarm operated at a low operating temperature.