Preparation of g-C3N4/SnO2 nanocomposites and their gas-sensing properties

g-C3N4/SnO2 nanocomposites were prepared by hydrothermal method. The microstructure and crystal phase of the samples were analyzed by X-ray diffraction, transmission electron microscopy, and N-2 adsorption-desorption analysis. The results showed that SnO2 nanoparticles which are rutile tetragonal structure and dispersed on the surface of g-C3N4 nanosheets. The g-C3N4 doping enlarged the specific surface area of the composites as well as decreased the crystallite size of SnO2. Compared with pure SnO2, the gas-sensing properties of the composites were enhanced. The sensor based on SnO2 doped with 3 wt% g-C(3)N(4 )showed good gas-sensing properties to formaldehyde, and the response was 506.4 to 100 ppm formaldehyde at 100 degree celsius, which was 4.8 times than the pure SnO2 sensor. It also exhibited good selectivity to formaldehyde at 100 degree celsius. Additionally, the response (S = 39.6) of the sensor based on 5 wt% g-C3N4-doped SnO2 was twice than the pure SnO2 sensor to 100 ppm acetone.