Sn3O4-SnO2 heterostructure for highly sensitive and selective NO2 sensing at low operating temperature

In this work, monophasic Sn3O4 and biphasic Sn3O4-SnO2 heterostructure composed of plentiful nanosheets were synthesized by using a simple one-step solvothermal method. Their morphology, structure, and composition were characterized by XRD, XPS, SEM and TEM. Also their NO2 sensing performance were tested systematacially. The results demonstrated that the gas sensor based on the Sn3O4-SnO2 composites exhibits excellent NO2 sensing performance including low operating temperature, high sensitivity and outstanding selectivity. Its sensitivity to 1 ppm NO2 is as high as 1395.0 ppm−1 while the operating temperature is as low as 50 °C. Its excellent NO2 sensing performance could be attributed to the formation of Sn3O4-SnO2 heterojunction which modulated the electrons effectively, abundant oxygen vacancies and high specific surface area which enhanced the adsorption of NO2.