Fe2O3/ Co3O4 composite nanoparticle ethanol sensor
  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. 
Ali Mirzaei, Sunghoon Park, Gun-Joo Sun, Hyejoon Kheel, Sangmin Lee,   Chongmu lee
physics.chem-ph