Development Of Tin Oxide/Graphene Oxide Composites Formaldehyde Gas Sensitive Materials

As a colorless but harmful gas,formaldehyde is mainly emitted from urea resin,which was widely used in indoor decorative materials and daily products.More attentions were pay to formaldehyde monitoring with the enhancement of environmental awareness.In order to avoid its hazards,the formaldehyde gas sensors with low detection limit,ultrahigh response,fast response and excellent stability have been became a burning issue.As a wide bandgap oxide semiconductor,tin oxide?SnO₂?was playing an important role in gas sensors due to their excellent sensing behaviors.This study takes the SnO₂ material as the main body of research.Two strategies are carried out by the structure regulation and the sensitization of graphene oxide to realize the optimization of the performance of formaldehyde gas detection.The specific content includes the following three parts:1.We prepared one-dimensional hollow structure SnO₂ nanofibers by electrospinning and graphene oxide?GO?with Hummer's method,and the gas sensitive materials are obtained by the two composite.The morphology,structure,specific surface area and composition of the samples were characterized by field emission scanning electron microscopy?FE-SEM?,X-ray diffraction?XRD?,Brunauer-Emmett-Teller?BET?and X-ray photoelectron spectroscopy?XPS?to evaluate its gas sensing properties.By combining with different carbon materials including GO,graphene?G?and carbon nanotubes?CNTs?,the sensitization performance was preliminarily explored.The effect of GO content on the gas sensitive properties of the composites was studied in detail and the optimum composite ratio was obtained.The experimental results show that the GO/SnO₂ composite has excellent sensitivity and selectivity for formaldehyde vapor and the optimum proportion of GO composite is 1 wt%,the optimum working temperature is 120?,the response of 100ppm formaldehyde gas is up to 32,and the detection limit is 500 ppb.2.On the basis of SnO₂ nanofibers,SnO₂ nanofibers@nanosheets hierarchical materials were obtained by hydrothermal method on the surface of SnO₂ nanofibers to develop SnO₂ nanosheets films.The morphology,structure and specific surface area of the prepared samples were characterized by SEM,TEM,XRD,BET and XPS.The effects of the graded structure on the gas sensitivity of the samples were systematically investigated,and the gas sensitive properties of the composite GO were preliminarily explored.The experimental results show that the optimum working temperature of SnO₂ hierarchical structure to formaldehyde is 120?,the response of 100 ppm formaldehyde is 57,and the gas sensing performance is increased by 1.2 times after compound 1 wt%GO.3.The cluster SnO₂ nanosheets were successfully prepared by hydrothermal method,and characterized by SEM,XRD and BET.The effects of pH value and trisodium citrate dihydrate weight on the SnO₂ nanosheets development were systematically studied.Combined with different carbon materials,the sensitivity of the composites was preliminarily studied.The influence of GO content on the gas sensing properties of the composites was systematically studied.The experimental results show that the optimum proportion of the composite GO to the cluster SnO₂ nanosheets is 1wt%,the optimum working temperature of the composite is 200?,and the response of100 ppm formaldehyde is 24,which is 2 times higher than SnO₂ monomer.