Enhanced performance of SnO2 nanowires ethanol sensor by functionalizing with La2O3

A SnO2 nanowires (NWs) sensor was coated with a functional La2O3 layer by solution deposition and its gas sensing characteristics were compared with those of an uncoated SnO2 NWs sensor. The responses (Ra/Rg, Ra: resistance in air, Rg: resistance in gas) of an undoped SnO2 NWs sensor to 100 ppm C2H5OH and CH3COCH3 were 10.5 and 9.6, respectively, while those to 100 ppm C3H8, CO, and H2 ranged from 3.1 to 3.3. The Ra/Rg values of the La2O3-coated SnO2 NWs to 100 ppm C2H5OH and CH3COCH3 increased to 57.3 and 34.9, respectively, but there was no significant change in the responses to C3H8, CO, and H2. The ∼5.5-fold enhancement in Ra/Rg to C2H5OH as well as the selective detection of C2H5OH in the interference gases such as C3H8, CO, and H2 was accomplished simultaneously by coating with La2O3. In particular, the selective discrimination of C2H5OH over CH3COCH3, which is a difficult issue on account their similar chemical nature, was possible.