Graphene And SnO₂-based Gas Sensor Materials

The gas sensors utilize the gas molecules and the gas type which is between sensitive material and gas while converted gas concentration to corresponding electric signal. We are focused on gas sensor developed research and commercial application because of its high sensitivity, simple structure, easy to use, low cost, etc. However, the conventional semiconductor oxide gas sensors were still many problems to solve and break, mainly reflected in higher operating temperatures, poor selectivity, stability of the device needs to be improved. Thus, the research hotpot is that improving the performance of sensitive materials which can be via different designs. In this study, the materials of tin dioxide/graphene oxide?SnO₂/RGO? and tungsten oxide / tin dioxide?WO₃/SnO₂? have been designed and synthesized, and then measured their gas-sensing performance,respectively. The mainly research contents were below:1. Graphene which is possessed extra-high specific surface area and ultra-low Johnson noise, mean while has a very excellent gas sensing performance at room temperature. Nevertheless, the graphene sensitive material which is low sensitivity for few gases and that limited detection range. The size of SnO₂ nanoparticles just was¹0nm which were uniform loading on graphene via facilely reduce-oxide reaction.Graphene as a substrate of carrier transport, SnO₂ nanoparticles as a gas-sensitive active sites when the gas-sensing response. In addition, due to excellent gas-sensing for ethanol with SnO₂ which have been expanded the response to ethanol with graphene?which have no response for ethanol?.2. The WO₃ nanoparticles loading on hollow sphere SnO₂ sensitive materials which have been designed as WO₃/SnO₂ nanocomposites. SnO₂ hollow spheres as a main material to build a porous gas-sensitive film, which were not only help to raise the utilization efficiency of gas-sensitive materials, but also can enhance the diffusion and transmission rate of gas molecules in the gas-sensitive film; the WO₃ nanoparticles supported on SnO₂ hollow spherical surface as a response active material to NO₂, which is exploited the excellent selectivity to NO₂ of WO₃. In this paper, the carbon microspheres as templates to synthesize WO₃/SnO₂ hollow spheres nanocomposites,and adjust the loading of WO₃ rates, the results show that the highest sensitivity and selectivity of gas sensing for NO₂ gas at the test conditions of operating temperature150 oC when the WO₃ loading proportion was 5 mol%.