Preparation And Functional Properties Of Indium Oxide Nanocomposite

Indium oxide is an important n-type semiconductor with a wide band gap,low resistivity and high catalysis.It is widely used in gas sensing,photocatalytic degradation,solar cells and other fields.This work mainly involves the investigation of the application of indium oxide materials in gas sensing and photocatalysis.The performance of semiconductor gas sensors,such as sensitivity,selectivity,stability,response recovery time,is directly related to the morphology and structure of the gas sensing material.Moreover,the key to the semiconductor photocatalysts is how to develop a photocatalytic material with high efficiency and broad spectrum response.Therefore,this thesis starts with the preparation of indium oxide and its nanocomposites.Firstly,a hollow structure of indium oxide nanomaterials was prepared by a hydrothermal method.And then they were loaded with different proportions of precious metals(gold and platinum).The gas-sensitive performance test of the binary nanocomposite structure is carried out.Finally,two kinds of the core-shell nanocomposites of TiO2(core)@In2O3(shell)and In2O3(core)@TiO2(shell)are prepared by a sol-gel method and a hydrothermal method.Gas sensing and photocatalytic performances of these nanocomposites are performed.Main research contents of this thesis are described as follows:(1)The hollow spherical structure of indium oxide nanoparticles was prepared by a hydrothermal method.Optimized synthesis conditions are:1:4 of the molar ratio of InCl3·4H2O to NH4HCO3;0.025 mol/L of the concentration of InCl3,the reaction temperature of 160? and 8 h of the reaction time is.The morphology and the composition of the products were characterized by XRD,SEM and TEM.(2)Noble metals modified In2O3 hollow nanospheres were prepared by in-situ reduction.The nanocomposites with various mass fractions of gold(1%,5%,and 10%)and platinum(1%,5%and 10%)were characterized by XRD,SEM,TEM and the following gas sensing properties toward n-butylamine.It was found that different ratios of Au-In2O3 and Pt-In2O3 nanocomposites reduced the optimum temperature of In2O3.And the sensitivity to n-butylamine was significantly enhanced compared with the pristine In2O3 hollow nanospheres.(3)TiO2(core)@In2O3(shell)core-shell nanocomposites were prepared by a sol-gel method and a hydrothermal method.Three kinds of the core-shell materials with the molar ratios of TiO2 to In2O3(1:7,1:10 and 1:15)were prepared respectively.N-butylamine was selected as the target gas.The results show that the sensitivity of the nanocomposites toward n-butylamine was improved to some extent.The nanocomposites with the In2O3/TiO2 molar ratio of 1:10 show the highest sensitivity among the as-prepared nanocomposites.(4)In2O3(core)@TiO2(shell)core-shell nanocomposites were prepared by a hydrothermal method and a sol-gel method.Four kinds of the core-shell materials with molar ratios of In2O3 to TiO2 of 1:5,1:7,1:10 and 1:15 were prepared,respectively.The photocatalytic performance test indicates that the photo-degradation efficiency of the TiO2@In2O3 core-shell nanocomposites was significantly improved,compared with the pure In2O3 and the pure TiO2.The highest photocatalytic efficiency(0.0128 min-1)can be found from the nanocomposites with the molar ratio of In2O3 to TiO2 of 1:10.