WO3-Co3O4 Compositions Prepared by the Sol-Gel Process: Structure and Gas-Sensing Properties

摘要

The structure and phase features of the WO3-Co3O4 compositions prepared by the sol-gel process are studied by X-ray powder diffraction, IR spectroscopy, scanning electron microscopy, thermogravimetry, and by specific surface determination from low-temperature nitrogen adsorption in the temperature range 200-800 degrees C. An appreciable rise is observed in the gas sensitivity of the compositions compared to the constituent oxides. The dependence of the CO and NO2 sensitivity on the two-phase composition is elucidated, and an explanation is given to the discovered trend. Low-power semiconductor sensors are manufactured, providing the determination of low nitrogen dioxide concentrations (<1 ppm) with good response and recovery times.