Novel Ag-SnO2-βC3N4 ternary nanocomposite based gas sensor for enhanced low-concentration NO2 sensing at room temperature

Herein, a novel gas sensor based on Ag nanoparticles, tin oxide and carbon nitride nanocomposite (Ag-SnO2-beta C3N4) was fabricated and its utility towards room-temperature NO2 gas sensing was investigated. TheAg-SnO2-beta C3N4 ternary nanocomposite was characterized with transmission electron microscopy (TEM), Energy dispersive X-ray (EDX) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) etc. The ternary heterojunction based sensor responded strongly to low concentrations of NO2 gas at room-temperature. For 5 ppm NO2 concentration, an excellent response time of 27.2 s for 90 % of response was achieved with higher recovery time of 110.5 s. The ternary nanocomposite sensor showed synergistic response which is similar to 1.14 times and similar to 1.9 times of that of the SnO2-C3N4 and pristine SnO2 sensors, respectively. The superior sensitivity of the ternary nanocomposite sensor is attributed to the higher conductivity and catalytic activity of the Ag-SnO2-beta C3N4 ternary nanocomposite. The enhanced sensing properties of Ag-SnO2-beta C3N4 sensor were discussed from the points of SnO2-beta C3N4 n-n heterojunction and Ag-SnO2-beta C3N4 Schottky contact on the basis of depletion layer model.