Facile Synthetic Methods Of ZnSnO₃ Composites And Its Application In Formaldehyde Detection

The indoor formaldehyde gas accumulation seriously affects human health.When the concentration of formaldehyde in the air reaches 0.4ppm-lppm,it will irritate and injure the nose,eyes,throat and cause discomfortable.When the concentration of formaldehyde is greater than 3ppm,it will cause cell tissue injury.The research work which has been published shown that ZnSnO3 has good gas sensing properties for formaldehyde detection,but it need operate at high temperature.In this paper,the gas sensing properties of rGO/ZnSnO3 and NiO@ZnSnO3 were improved and the optimum operating temperature of them was reduced.In order to study the gas sensing mechanism of the materials,the materials' crystal structure crystallinity and interface were analyzed by means of X-ray powder diffraction(XRD)and High-resolution electron microscopy(HRTEM),the micro morphology element distribution and ratio were observed by scanning electron microscopy and energy dispersive X-ray detector(SEM-EDX),the specific surface area pore size distribution the surface chemical elements and surface electronic structure were surveyed by the Brunauer-Emmett-Teller(BET)and by X-ray photoelectron spectroscopy(XPS),and the optimum calcination temperature was confirmed by thermo-gravimetric analysis(TG-DTA)and the response data of gas sensing materials at different operating temperatures.rGO/ZnSnO3 composite is formed by single layer reduced graphene and hierarchical microspheres which has a large specific surface area.The sensing experiments show that the sensor based on 3wt%rGO composite exhibits high sensitivity(low limit of detection),excellent selectivity and good linearity responses in the formaldehyde concentration range from 1 to 10 ppm at operating temperature of 103?.NiO@ZnSnO3 composite was synthesized,in order to detect the low concentration formaldehyde.The sensing experiments show that the optimal ratio of ZnSn03:NiO is 10:1,the optimum calcination temperature is 450 ?,and the composites show n-type semiconductor material performance and high sensitivity to 0.1?1ppm formaldehyde.