NO2 detection and redox capacitance reaction of Ag doped SnO2/rGO aerogel at room temperature

•Doping Ag as a catalyst to improve the internal electron mobility is proposed.•The Ag-SnO2/RGO aerogel exhibits the ability of capacitance for redox by C-V test.•The Ag-SnO2/RGO aerogel responses better at RT instead of heating conditions.•A non-liner relationship between gas concentration and response is observed. A new material of Ag-SnO2/rGO aerogel is fabricated by the sol-gel method and freeze-drying technique. The SnO2 particles are tightly arranged on the rGO sheets to form a p-n heterojunction, and the rGO aerogel possesses abundant pore structures for effective adsorption. Besides, the Ag particles are dispersed on the surface as a catalyst to improve the internal electron mobility, further promoting the gas-sensing performance. To be noted, the Ag-SnO2/rGO aerogel can exhibit a response of 2.13 towards 50 ppm NO2 at RT instead of heating conditions, and shows a cyclic capacitance property of redox. Moreover, the non-linear growth between gas concentration and response is observed, which proves the chemical adsorption that results in the high selectivity.