Mesoporous flower-like SnO2/GaN heterostructures for ppb-level NO2 detection at low temperature

It is essential to improve the detection response and maintain good stability of the gas sensor to be able to effectively monitor the ppb level harmful NO 2 gas. This work was dedicated to improving the sensing performance of NO 2 gas sensors by synthesizing flower-like structure SnO 2 /GaN composites using a combination of solvothermal and ultrasonic mixing method. The introduction of GaN increased the specific surface area of SnO 2 and provided more adsorption sites. Gas-sensitive test results showed that the SnO 2 /GaN composites exhibited excellent NO 2 response (42–1 ppm of NO 2 ) and lower detection limit (100 ppb) at lower operation temperature of 130 °C. In addition, the fluctuation in the initial resistance and response of the SnO 2 /GaN composites to 20 ppm of NO 2 within one month were small. The improved sensing performance was attributed to the unique flower-like structure of SnO 2 , the excellent thermodynamic stability of GaN and the heterogeneous interface of SnO 2 /GaN. This work provides a new design strategy for the development of highly sensitive ppb-level NO 2 sensors for atmospheric environmental monitoring.