Study of WO3-In2O3 nanocomposites for highly sensitive ENCO and NO2 gas sensors

Pure semiconductor tungsten oxide (WO3), indium oxide (In2O3) and mixed nanocomposites with different WO3 to In2O3 ratios were successfully synthesized by simple sol-gel method following calcination at 600 degrees C. The morphology, phase composition and features of crustal structure of the materials were studied by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transition electron microscopy and electron paramagnetic resonance spectroscopy. It was found that the nanocomposite materials are characterized by fine crystallinity of 8-38 nm, highly defective crystal cells and presence of delocalized electrons in their structures, which can significantly affect gas sensitivity. The gas sensors based on WO3-In2O3 composite structures exhibited excellent CO and NO2 detecting performance at optimal operating temperature of similar to 240 degrees C and similar to 140 degrees C, respectively.