Effects of rare earth element doping on the ethanol gas-sensing performance of three-dimensionally ordered macroporous In2O3

Rare earth (Tm, Er, La, Yb and Ce)-doped In2O3 nanostructures with three-dimensionally ordered macroporous structures (3DOM) were prepared by a colloidal crystal templating method, and their ethanol sensing properties were investigated. Rare earth doping improved the gas response and lowered the optimum operating temperature. Tm-doped 3DOM In2O3 had the best gas-sensing performance, and the gas sensitivity for 100 ppm ethanol was seven times higher than that of pure 3DOM In2O3. The reason for the different sensitivities generated by the five doping elements and the underlying mechanism of the enhanced gas response for the samples were studied.