Structural, optical, and selective ethanol sensing properties of p-type semiconducting CoNb2O6 nanopowder

Abstract

This paper described the chemiresistive gas sensing characteristics of CoNb2O6 nanopowder prepared by a wet chemical technique. Prepared CoNb2O6 nanopowder was characterized using different analytical techniques. Thermal properties were studied using thermal analysis (TG/DTA), while purity and crystal structure were confirmed by X-ray powder diffraction (XRD). Morphology was studied using scanning electron microscopy (SEM). Transmission electron microscope (TEM) elemental confirmation was carried out by energy dispersive X-ray spectroscopy (EDX) and optical band gap from UV–Visible diffuse reflectance spectra (DRS). During these studies, it was observed that crystalline orthorhombic CoNb2O6 was obtained by heat treatment at 700°C. The gas sensing behavior of CoNb2O6 nanopowder was analyzed by measuring the changes in resistance of the sensor material in the presence of each reducing gas, including ethanol, H2S, NH3, and LPG as a function of the operating temperatures, gas concentrations, and response time. CoNb2O6 based gas sensors showed p-type behavior and were able to detect ethanol vapor as low as several ppm and at a relatively low operating temperature of 130°C. The sensors showed high sensitivity and repeatability, as well as fast response and recovery toward ethanol vapor.