Mesoporous Assembled SnO₂ Nanospheres: Controlled Synthesis And Ethanol Sensor Application

Tin dioxide (SnO2), as an n-type semiconductor with a wide band gap (3.6 eV), has many potential applications including Li-ion batteries, solar cells, catalysis, optoelectronic devices, in which out-standing gas sensing is the most important property. Its sensing performance as well as other applications is affected by several structural parameters such as particle size, specific surface area, and crystallinity. Many SnO2 hollow spheres show the superior gas-sensing properties, and finding some other shape, and its gas sensing property of the material over the hollow spheres is the focus of our research. In addition, LDHs vertical films and SnO2 nanomaterials all show many advantages. If we could collect the advantages of the two materials and load SnO2 to NiAl-LDHs vertical film to synthesize a new type of composite film sensor, is a rewarding job. The main results are listed as following:1. Three types of SnO2 nanospheres with varied inner structures have been prepared by a cetyltrimethylammonium bromide (CTAB)-assisted solvothermal treatment method:nanocones assembled spheres, rough hollow spheres and solid spheres. It is found that the solvent amount ratio of ethanol to water has an important influence on the formation of morphologies of SnO2 nanospheres besides CTAB. It is unexpected that the nanocones assembled spheres rather than hollow spheres showed a superior ethanol sensing response among the three types of nanospheres. Careful structure characterizations using field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and Brunauer-Emmett-Teller (BET) surface area reveal the inner structures and crystallization behaviour differences. It is finally attributed to the difference on how electrons passed through the which were induced by assembly fashion difference, which lead to varied structural stability and more importantly, transfer.2. NiAl-LDHs vertical film was successfully prepared by a hydrothermal method onto the surface of gas sensor. After that, loading SnO2 to the NiAl-LDHs vertical film, then test its gas-sensing. Its gas-sensing is not good, maybe NiAl-LDHs vertical film sheet and sheet just only overlap joint, shows a bad electrical conductivity, resulting that resistance is too large and a poor gas performance. But we get a good strcture of NiAl-LDHs vertical film, setting a good grounding for loading SnO2 on it.