Ultrasensitive and selective C2H5OH sensors using Rh-loaded In2O3 hollow spheres

Rh-loaded In2O3 hollow spheres with diameters of similar to 2 mm were prepared by a one-pot hydrothermal reaction of aqueous solution containing indium nitrate, rhodium chloride, and glucose and subsequent heat treatment at 500 degrees C for 2 h. The response to 100 ppm C2H5OH (R-a/R-g, R-a: resistance in air, R-g: resistance in gas) of 1.67 at% Rh-loaded In2O3 hollow spheres was 4748, which was similar to 180 times higher than that of pure In2O3 hollow spheres. Rh loading decreased the temperature for maximum gas response from 475 degrees C to 371 degrees C, which also enhanced the selectivity to C2H5OH 15.1-24.7 times and recovery speed. The ultrahigh sensitivity and selectivity to C2H5OH, the lower sensing temperature, and the reduced recovery time were attributed to electronic interactions between Rh and In2O3 and the promotion of catalytic dissociation of C2H5OH into reactive gases.