Enhancement of NO2 gas sensing response based on ordered mesoporous Fe-doped In2O3

Ordered mesoporous Fe-In2O3 has been synthesized via a nanocasting route using the three-dimensional (3D) cubic mesoporous KIT-6 silica as a hard template. Various techniques including X-ray diffraction (XRD), nitrogen adsorption–desorption and transmission electron microscopy (TEM) as well as X-ray photoelectron spectroscopy (XPS) were employed for the material characterization. All the results demonstrate that the obtained Fe-doped In2O3 displays the high surface area, ordered mesoporous structure and well crystallite. The NO2 sensing properties of the sensors based on mesoporous pure In2O3 and Fe-doped In2O3 samples were detected by a static test system. The sensor utilizing mesoporous Fe-doped In2O3 exhibits much higher response to NO2 gas compared to that using mesoporous pure In2O3 prepared by the same nanocasting technique. The excellent gas sensing property of mesoporous Fe-doped In2O3 is associated with its higher surface area and pore volume which induce highly effective surface interaction between the target gas molecules and the surface active sites. Moreover, the improved sensing behavior to NO2 has been linked to the incorporation of iron species on the sensor, favoring the effective adsorption of NO2 molecules on the surface. All the factors are obviously beneficial for enhancing the gas-sensing performance.