Xylene gas sensing properties of hydrothermal synthesized SnO2-Co3O4 microstructure

As one of representative indoors pollutants, xylene is harmful to human health, thus it is crucial to detect subppm xylene efficiently and accurately. In this paper, the SnO2-Co3O4 nanocomposite with irregular nanostructures were synthesized through a simple hydrothermal route and used as sensing materials for detecting xylene. The SnO2-Co3O4 nanostructures showed much larger BET surface area (123.5 m(2) g(-1)) than that of the pure Co3O4 (25.5 m(2) g(-1)). As expected, the SnO2-Co3O4 (Sn/Co = 15 at%) based sensor showed not only the highest response (S = 101.9 towards 100 ppm) at 175 degrees C, which was about 16.4 times higher than that of pure Co3O4 but also superior selectivity to xylene against ethanol (S-xyle(ne)/S-ethanol = 12.4) and acetone (S-xyle(ne)/S-acetone = 9.7). In addition, the detection limit for xylene was as low as 50 ppb. The greatly promoted gas sensing performance was attributed to the synergistic combination between SnO2 and Co3O4, the nanoscale p-n heterojunction, the existence of small particles and the large specific surface area. The SnO2-Co3O4 nanocomposite based sensor with high selectivity and ppb-level detection limit to xylene provided an effective solution for precise monitoring of indoor air pollution.