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

Abstract

Rh-loaded In₂O₃ hollow spheres with diameters of ∼2 μm were prepared by a one-pot hydrothermal reaction of aqueous solution containing indium nitrate, rhodium chloride, and glucose and subsequent heat treatment at 500 °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 ∼180 times higher than that of pure In₂O₃ hollow spheres. Rh loading decreased the temperature for maximum gas response from 475 °C to 371 °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.