Gas sensing characteristics of p-type Cr2O3 and Co3O4 nanofibers depending on inter-particle connectivity

p-Type Cr2O3 and Co3O4 oxide semiconductor nanofibers, with different connecting configurations, were prepared by controlling the ultrasonic disintegration of nanofibers and their C2H5OH sensing characteristics were investigated. The ratios between resistances in 100 ppm C2H5OH, and air, of Cr2O3 (at 350 °C) and Co3O4 sensors (at 300 °C) consisting of long nanofibers were found to be 22.1 ± 1.4 and 82.4 ± 10.2, respectively. These values were significantly higher than those of Cr2O3 and Co3O4 sensors (4.9 ± 1.1 and 5.7 ± 1.4), which consisted of less-connective primary particles disintegrated from nanofibers. The decrease of gas response, and increase in sensor resistance, with ultrasonic disintegration of nanofibers is explained in relation to a decrease of contact area between primary particles, indicating that inter-particle connectivity is a key parameter in determining the gas response of p-type oxide semiconductors.