Synthesis Of Rare Earth-Doped Indium Oxide Hollow Nanomaterialsandapplication For Gas Sensing

Indium oxide semiconductor sensors have been widely used to monitorthe target gases for their excellent gas-sensing performance. The sensingproperties are directly influenced by the morphologies, structures andcompositions of semiconductor nanomaterials. In the present work, hollowindium oxide nanomaterials were prepared by using carbon spheres astemplates, and rare earth elements were doped to improve the gas-sensingproperties. The following is the main contents:1. Different morphologies of indium oxide nanospheres were synthesisedby using carbon spheres as templates which were prepared by theglucose-hydrothemal treatments. The gas-sensing properties of the obtainedmaterials were measured and sudied combining with the gas-sensingmechanism. The results showed that indium oxide hollow spheres with adiameter of ca.300nm exhibited the highest sensing performances to alcoholvapors, and the reason may be owe to their higher specific surface areas（43.704m2/g） and porous structures, which can provide more active sites toimprove the interaction between gases and material surfaces. 2. Rare earth （RE=Er, La, Yb, Ce, Y, Eu）-doped hollow indium oxidenanospheres were prepared by a carbon sphere-template route, and thegas-sensing properties of the synthesized hollow spheres were investigated.The doping of Er³⁺, La³⁺, Yb³⁺greatly increased the sensitivities of indiumoxide sensors and Er³⁺, La³⁺reduced the operating temperatures. Furthermore,the prepared rare earth-doped sensors had short response/recovery times andexhibited high selectivities and stabilities to alcohol vapors. The gas-sensingmechanism and XPS results showed that the enhancements of sensitivities ofRE-doped indium oxide sensors may be attributed to their large latticedistortions and electronic interactions between In³⁺and RE3+, resulting inmore adsorption oxygen to participate in the reaction with alcohol vapors onthe surface of the materials.3. Erbium （Er）-doped hollow indium oxide nanospheres were preparedby using carbon spheres as templates and the impact of erbium-doped contentson the alcohol-sensing properties was studies. The result indicated that the5.0mol％Er-doped In2O3sensor exhibited the highest sensitivity and favorableselectivity to alcohol vapors.