The effects of excess carbon on the surface area and crystallinity of TiO2 powders prepared by oxidizing mechanically-synthesized TiC and their CO gas-sensing properties

Abstract

Abstract TiC-ec (with 20 at% excess carbon), with TiC and TiN powders as comparative samples, were synthesized via ball milling. TiO 2 -ec and TiO 2 -n, TiO 2 -c sensing materials were prepared by oxidizing the synthesized TiC-ec, TiC, and TiN powders at 600 °C. Structural characterization was performed via X-ray diffraction, field emission scattering electron microscopy (FE-SEM), and transmission electron microscopy (TEM). The mean particle size of TiO 2 -ec was the smallest (40.8 nm), and its SSA was the largest (14.3 m 2 /g). The anatase crystallinity of the TiO 2 -ec powder was higher than those of the TiO 2 -n and TiO 2 -c samples, although the particle size was the smallest. The response of TiO 2 -ec to 1000 ppm CO gas at a working temperature of 550 °C was the highest (4.0) while the TiO 2 -c and TiO 2 -n samples showed a smaller response (1.2 and 1.4, respectively). The improved sensing properties of the TiO 2 -ec samples were due to a better crystallinity and larger surface area. Therefore, the enhanced surface area and crystallinity of the TiO 2 -ec are believed to be related to the presence of excess carbon.