Ultra-fast real time ethanol sensing behavior and reduction in optical bandgap of the hydrothermally synthesized V2O5/ZnO nanocomposites

Abstract

Owing to the significance of metal oxides based nanostructures for the gas sensing applications, this work reports the hybrid V₂O₅/ZnO nano-particles/rods nanocomposites (with different V₂O₅-ZnO contents ratios; (10:1 (VZ-I), 8:1 (VZ-II) and 6:1 (VZ-III)) prepared via hydrothermal method and characterized for structure, morphology, composition, photoluminescence and optical bandgap by XRD, FESEM, EDX, Photo-Luminescence (PL) and UV–Vis spectroscopy, respectively. Structure of the nanocomposite was reported to consist of both V₂O₅ and ZnO phases, alongwith V₂O₃ phase in slight amount at the hetero-structure. Morphology of the nanocomposites is observed as V₂O₅ nanoparticles (∼10–20 nm), densely anchored into the ZnO nanorods (∼500–700 nm), executing a large surface area. PL spectra indicates that the V₂O₅ emissions peaks get increased in intensity in nanocomposites but decrease with further increase in the ZnO contents. Tauc’s plot is applied to estimate the optical bandgap variation, showing that the bandgap of the nanocomposites lies within those of V₂O₅ and ZnO individual metal oxides, However, it lowers below that of V₂O₅ for the VZ-III nanocomposite. Gas sensors based, on the nanocomposites, were tested for sensitivity in static and dynamic response modes at three distinct temperatures, 100, 140 and 190 °C and the VZ-III nanocomposites exhibits a stable and fast response pattern as compared with the other two nanocomposites and hence declares the VZ-III nanocomposites a promising candidate for gas sensors which is explained on the basis of surface redox reactions and energy band models.