Synthesis of mesoporous Nb-doped V2O5 for ethanol detection - experimental and DFT studies

Mesoporous nanospheres of pristine V₂O₅ and Nb-doped V₂O₅ (1 %, 3 %, and 5 % Nb) were synthesized via a facile hydrothermal method for ethanol sensing applications. Structural, morphological, optical, and compositional analyses were performed using X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), ultraviolet–visible (UV–Vis) spectroscopy, and X-ray photoelectron spectroscopy (XPS), while Brunauer–Emmett–Teller (BET) analysis assessed surface area and porosity. Density functional theory (DFT) calculations were employed to investigate structural and optical properties, providing good agreement with experimental results. Nb doping reduced the crystal size from 50.26 nm (V-pure) to 43.42 nm (VNb-5) and increased the surface area from 25.784 m²/g to 84.894 m²/g. Gas sensing tests in a static chamber for various volatile organic compounds revealed enhanced selectivity towards ethanol, with the VNb-5 sensor exhibiting a sensitivity of 1.55 for 100 ppm ethanol at 220 °C, along with response and recovery times of 34.79 s and 913.25 s, respectively. The improved sensing performance is attributed to increased surface-active sites, enhanced adsorption-desorption kinetics, and catalytic effects introduced by Nb doping, making VNb-5 a promising candidate for ethanol detection in breathalyzer and environmental monitoring applications.