Mesoporous metal oxide–α-Fe2O3 nanocomposites for sensing formaldehyde and ethanol at room temperature

Abstract The present study describes the synthesis of mesoporous metal oxide–α-Fe2O3 nanocomposites and investigation of their gas-sensing performance. Mesoporous Li2O-doped Fe2O3 and SnO2–Fe2O3 nanocomposites were synthesized employing a nanocasting technique using KIT-6 as the structure guiding template. The structural features of synthesized mesostructures were analyzed using X-ray diffraction, Brunauer–Emmett–Teller studies and Fourier transform infrared spectroscopy. The morphological features of metal oxide–Fe2O3 nanocomposites were observed by scanning electron microscopy and transmission electron microscopy. Thin films of mesoporous metal-oxide nanocomposites were prepared and studied as sensors toward formaldehyde (HCHO) and ethanol (C2H5OH) over the operating temperature range of 25–200 °C. The SnO2–Fe2O3 sensor showed maximum sensing response toward HCHO at 150 °C after attainment of sufficient ordering of structure at high temperatures. However, Li2O-doped Fe2O3 exhibited very high response of 6.08 and 5.82 for HCHO and C2H5OH, respectively, at room temperature (25 °C). Gas-sensing behaviors of nanocomposites along with the sensing phenomenon were explained on the basis of their mesostructures and crystallinity.