Selective ethanol gas sensing behavior of mesoporous n-type semiconducting FeNbO4 nanopowder obtained by niobium–citrate process

• FeNbO4 nanopowder was synthesized by low temperature solution-based method.
• FeNbO4 shows high sensing response in ethanol at low operating temperature.
• Mesoporous structure can enhance the ethanol sensing property of FeNbO4.
• The ethanol sensing mechanism of FeNbO4 is found out to be different.

Beyond the most investigated mesoporous silica and carbon based materials, metal oxides have attracted considerable interest due to their more diverse electronic functionality, which includes gas sensing activities, semiconductor characteristics and magnetic properties. In this paper, we describe the fabrication, characterization and application of mesoporous FeNbO4 nanopowder for ethanol gas sensing application. FeNbO4 nanopowder was synthesized via the niobium–citrate complex method, without using any surfactant and size selection medium. Thermal stability and structure of the nanopowder was analyzed by thermogravimetric analysis (TG/DTA) and X-ray diffraction analysis (XRD). Structural analysis confirmed the formation of FeNbO4 with monoclinic structure. The particle size, electrical and optical properties were also systemically investigated by means of transmission electron microscopy (TEM), impedance and diffused reflectance spectra. Nitrogen adsorption isotherms of the FeNbO4 were type IV with hysteresis loops of type H3 indicating well-defined pore structure with mesoporous nature. The sensing characteristics of FeNbO4 nanopowder such as sensitivity, operating temperature and response time, were studied in the presence of ethanol (C2H5OH). Experimental result confirmed that a higher response to ethanol at relatively lower operating temperature of 200 °C.