SnO-Sn₃O₄ heterostructural gas sensor with high response and selectivity to parts-per-billion-level NO₂ at low...

Considering the harmfulness of nitrogen dioxide (NO₂), it is important to develop NO₂ sensors with high responses and low limits of detection. In this study, we synthesize a novel SnO-Sn₃O₄ heterostructure through a one-step solvothermal method, which is used for the first time as an NO₂ sensor. The material exhibits three-dimensional flower-like microparticles assembled by two-dimensional nanosheets, in situ-formed SnO-Sn₃O₄ heterostructures, and large specific surface area. Gas sensing measurements show that the responses of the SnO-Sn₃O₄ heterostructure to 500 ppb NO₂ 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-Sn₃O₄ heterostructure has an excellent selectivity to NO₂, 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-Sn₃O₄ p-n heterojunctions and large specific surface area. Therefore, the SnO-Sn₃O₄ heterostructure having excellent NO₂ sensing performances is very promising for applications as an NO₂ sensor or alarm operated at a low operating temperature.