Fe-incorporated ZnO-TiO2 Nanocomposites for Improved CO2 Sensing

The nanoscaled ZnO-TiO2 and Fe-incorporated ZnO-TiO2 nanocomposite powders were synthesized via hydrothermal route at 120 degrees C and characterized for their potential use in gas sensing application. Both ZnO-TiO2 and Fe-incorporated ZnO-TiO2 nanocomposites exhibit crystalline phases corresponding to hexagonal wurtzite ZnO and anatase TiO2. The average crystallite size of ZnO-TiO2 and 0.1, 0.2, 0.3, 0.4, 0.5 Fe-incorporated ZnO-TiO2 nanocomposites was determined to be 40.40, 31.36, 39.42, 30.62, 31.57, 29.73 nm, respectively. Formations of Zn-O-Ti bonds and Ti-O or Zn-O were confirmed by FTIR. Scanning electron microscopy images showed uniform porous grains of nanocomposites. The homogeneous incorporation of Fe without the formation of secondary iron phases and additional oxygen vacancies in Fe-doped samples were confirmed by EDAX. The thick film of ZnO-TiO2 and Fe-incorporated ZnO-TiO2 nanocomposites were fabricated using a traditional screen printing setup. Thick films exhibited a nonlinear I-V behavior, indicative of hybrid nature of the nanocomposites. The average thickness of undoped ZnO-TiO2 nanocomposite was found to be 30 um. The CO2 sensing response with different compositions of Fe-incorporated ZnO-TiO2 results determined that 0.5 mol% Fe-incorporated ZnO-TiO2 nanocomposites (FZT5) showed the highest response to 286 ppm at ~280 degrees C. Therefore, Fe-doped ZnO-TiO2 nanocomposites can be effective materials for real-time CO2 detection with excellent response and recovery times.