Preparation And Engineering On Gas-Sensing Performance Of Indium Oxide Nanocomposites

In2O3 is an excellent n-type semiconductor gas-sensing material, which is extensively applied in gas sensor. Regulating the structure and composition is usually used to improve the properties of the material. In this paper, we synthesis a room temperature gas-sensing material by intergrating indium oxide and graphene; and we prepared Au loaded 3 DOM In2O3 by template method, the gas-sensing performance is also discussed. The major work has been done as following in this paper:1. The synthesis and the gas-sensing performance of NO2 at room temperature of In2O3-rGO nanocomposite. First, the graphene oxide (GO) was synthesized by improved Hummers method, then made the In2O3 nanoparticles grow onto graphene by hydrothermal treatment, and prepared the In2O3-rGO by further reduced, the NO2 gas-sensing properties at room temperature was also discussed. We use TEM, AFM, XPS, Raman, XRD and FTIR to characterize the In2O3-rGO nanocomposite in detail. It was observed that the as prepared GO had single-layer structure, In2O3-rGO nanocomposite with well distribution of small sized In2O3 nanoparticles, ca.lOnm. After hythermal treatment and further reduced, the reduction degree of GO was increased. In2O3-rGO nanocomposites with different rGO loading were successfully fabricated, and the In2O3-rGO (0.72%) reaches maximum response operated at room temperature. The In2O3-rGO (0.72%) sensor exhibits high response (8.25), short response time (4 min) and recovery time (24 min), and excellent selectivity for detection of 30ppm NO2 at room temperature. We study the sensing mechanism of the In2O3-rGO as well.2. The synthesis of Au-loaded 3DOM In2O3 and its sensing properties and sensing mechanism of C2H5OH has been researched as well. We choosen PMMA as template, In(NO3)3·4.5H2O as In precursor to prepared 3DOM In2O3. Then added HAuCl4, prepared Au-loaded 3DOM In2O3 by reduction method. From TEM and SEM, the nanocomposites possessed unbroken skeleton structure after the load of Au, and the size of Au nanoparticles were uniform, ca.5nm. The actual Au content of the Au-loaded 3DOM In2O3 was determined by the EDS and ICP-AES technique, the actual Au content was 0.39wt%. The combination of small size Au nanoparticles and 3DOM structure effectively improves the gas-sensing profermance for C2H5OH. The response is 205 when the sensor is exposed to 100 ppm ethanol at the optimal operating temperature of 230℃, and the response and recovery time of the Au-loaded 3DOM In2O3 nanocomposites are 15s and 21s, and the selectivity for detection C2H5OH is also excellent. The sensing mechanism of C2H5OH is studied by temperature-programmed surface reaction (TPSR).