In2O3 sensitized disordered porous SnO2 aerogel with remarkable gas-sensing properties at room temperature

This study aimed at the preparation of In2O3 sensitized disordered porous SnO2 aerogel (In2O3/SnO2) gas-sensing material by a sol-gel hard template method, and tested its gas-sensing properties to NOx gas at room temperature. The remarkable gas-sensing material was achieved by doped In2O3 into disordered porous SnO2 aerogel. The SiO2 could catalyze the SnCl2·2H2O to form the sol-gel system when the Sn, In and Si sources were mixed in alcohol and water, the silicon templates were formed during the reaction, and the disordered porous In2O3/SnO2 aerogel composite was obtained when the silicon templates were removed. When the doped concentration of In2O3 was 0.1%, the composite exhibited the highest sensitivity and selectivity. For doping 0.1% In2O3 sample, when the NOx concentration was 100 ppm, the response reached 80.3%, the response time was only 2.0 s. The detection limit to NOx gas reached 0.08 ppm. The response of sample to NOx was much higher than the same concentration other gases (NH3, H2, O2 and N2). The gas sensing mechanism was proposed that the addition of In2O3 into SnO2 enhanced the catalytic activity for the reaction. In addition, the morphology and unique structure were helpful to the gas reaction on the surface of the sensing materials. The prepared In2O3/SnO2 composite immensely reduced the dosage of the much expensive In element, and had the much higher response, which would have a great development space in the gas sensor field.