Highly sensitive and humidity-independent ethanol sensors based on In2O3 nanoflower/SnO2 nanoparticle composites

Abstract

As an ethanol sensing material, the composites of In₂O₃–SnO₂ were composed of In₂O₃ microflowers and SnO₂ nanoparticles. Both In₂O₃ microflowers and SnO₂ nanoparticles were synthesized by hydrothermal method and then mixed in an ultrasonic environment. The morphology and phase composition of the as-synthesized samples were characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The results on gas sensing properties showed that when the mass ratio of In₂O₃ and SnO₂ was 2 : 1, the sensor based on the as-prepared In₂O₃–SnO₂ composite exhibited high response and good selectivity to ethanol at 250 °C. The response to 100 ppm ethanol gas was 53.2. UV illumination stabilized the responses of the sensors while the relative humidity increased. The gas sensing mechanism proposed was that the addition of SnO₂ to In₂O₃ enhanced the catalytic activity for the ethanol reaction, which changed the electrical resistance of the materials. Besides, the morphology was helpful to the gas reaction on the surface of the sensing materials.