Concentration modulated vanadium oxide nanostructures for NO2 gas sensing

Vanadium Oxide (V2O5) nanostructures have been prepared via a simple and inexpensive hydrothermal method using ammonium metavanadate as a vanadium precursor along with oxalic acid. Present work demonstrates the effect of concentration (0.1–0.4 M) variation on gas sensing performance of hydrothermally prepared vanadium pentoxide. The structural, morphological, functional group, and optical properties of V2O5 nanostructure have been investigated by using different characterization techniques like X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), Fourier Transform Infra-Red (FTIR) Spectroscopy, Raman spectroscopy, and Diffused Reflectance Spectroscopy (DRS) studies respectively. The structural analysis revealed orthorhombic V2O5 phase formation with the c-axis orientation along (001) plane. The SEM images revealed platelet-like nanostructures, agglomerated nano structure, and clusters of elongated nano structure. The variation in band gap from 2.06 to 2.14 eV is observed with a change in precursor conc. The BET study indicates good specific surface area and optimum pore diameter. The Photoluminescence shows a centered peak arising at characteristic wavelength 709.25 nm and some other peaks observed at 540.91 nm, 470.86 nm and 391.50 nm which is good for gas sensing application. The sensing selectivity was high for NO2 gas detection at 150 °C. All samples revealed good response with fast response and recovery time. Sample prepared with 0.3 M concentration exhibited the best response attributed to optimum pore size and high surface area which governs superior sensing features. The response of V2O5 is found to be 13% towards 100 ppm NO2 gas, while response and recovery time is 4 and 55 s respectively. The present work depicts the results of NO2 gas sensing with fast response and recovery time at relatively low working temperature (150 ℃). Hence it explores the use of this material as a potential candidature for the fabrication of vanadium oxide-based gas sensors.