Preparation Of Porous Indium-based Composites And Gas Sensing Performance Of The Template Method

One dimensional nanostructures show excellent performance as chemical sensor. Inthis paper, the one-dimensional highly crystalline mesoporous In2O3nanomaterials weresynthesized by template method and the NOxgas sensing properties of theone-dimensional In2O3nanomaterials was measured at room temperature. To investigatethe response mechanism of the gas sensitivity, we charactered the nanomaterials byXRD, BET, TEM, and XPS and so on.Using SBA-16as template, In(NO3)3solution as precursor, the highly crystallinemesoporous In2O3nanowires were synthesized by the template-calcined method. Thediameter of the INW-2sample which synthesized by the0.2mol L-1In(NO3)3solutionis about4-8nm, with the pore size is3-5nm and has high density of defects. Thesurface of the nanowires is coated by an ultrathin SiO2layer, which provides a greaternumber of available active centers for gas/surface reactions. The INW-2sensorpossesses high response and selectivity to NOxat room temperature (RT). It showshigher NOxgas sensing performance with low detection limit of970ppb and highresponse of115.6to97.0ppm NOxat RT.By the template-hydrothermal-calcination method, mesoporous In2O3nanosheetswere synthesized with0.3mol L-1In(NO3)3solution. The loose structure of thenanosheets provides a larger specific surface area with the pore size is about3-5nm.The gas sensing tests shows the sensitivity of NOxreached587.5and the response timeof87s at room temperature.In addition, by dopping KNO3, the gas sensitive properties of nanomaterials aresignificantly improved, the sensitivity of NOxto97ppm is151.78and the response timeis only12s, the detection limitation decreased to48.5ppb at RT. With the increasing ofKNO3content, the mesoporous on the nanomatrials reduced and the ordered nanowiresarray formed. Metallic element doped on the surfaces searved as alkaline center andbenefits the diffusion and the adsorption for the target gas.