  In this study Fe2O3/Co3O4 nanocomposites were synthesized by using a simple
hydrothermal route. The X-ray diffraction analysis results showed that
synthesized powders were pure, and nanocrystalline in nature. Moreover,
Scanning electron microscopy revealed that Fe2O3 nanoparticles had spherical
shapes while Co3O4 particles had a rod-like morphology. Ethanol sensing
properties of Fe2O3/Co3O4 nanocomposites were examined and compared with those
of pristine Fe2O3 nanoparticles. It was shown that the gas sensing properties
of Fe2O3/Co3O4 nanocomposites were superior to those of pristine Fe2O3
nanoparticles and for all concentrations of ethanol, the response of the
nanocomposite sensor was higher than the pristine Fe2O3 nanoparticle sensor. In
detail, the response of Fe2O3/Co3O4 nanocomposite sensor to 200 ppm of ethanol
at 300{\deg}C was about 3 times higher than pristine one. Also in general, the
response and recovery times of Fe2O3/Co3O4 nanocomposite sensor were shorter
than those of the pristine one. The improved sensing characteristics of the
Fe2O3/Co3O4 sensor were attributed to a combination of several effects: the
formation of a potential barrier at the Fe2O3-Co3O4 interface, the enhanced
modulation of the conduction channel width accompanying the adsorption and
desorption of ethanol gas, the catalytic activity of Co3O4 for the oxidation of
ethanol, the stronger oxygen adsorption of p-type Co3O4, and the formation of
preferential adsorption sites.
