Fabrication, Characterization, and Gas Sensing Performance of Chromium Doped WO3 Nanoflakes

Pristine and chromium (Cr) doped WO3 nanoflakes (NFs) with various concentrations were successfully fabricated by a facile hydrothermal technique on alumina (Al2O3) substrates. The structural, optical, and morphological properties of these NFs were investigated by x-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-Visible diffusion reflectance spectroscopy (UV–Vis DRS), and x-ray photoelectron spectroscopy. Gas sensor tests were performed against various volatile organic compounds such as ethanol, xylene, toluene, and isopropanol gases in the temperature range between 50 °C and 250 °C. According to the results of these tests, the isopropanol sensing ability of WO3 NFs is enhanced with Cr-doping due to the increasing active adsorption sites on the surface and improved surface reactions with the decreasing band gap energy. The highest isopropanol sensing response which was calculated to be 77.1 has been obtained by nominally 2% Cr doping at the optimal operating temperature of 150 °C.