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In this paper, we report on microstructural, optical and electrical properties of alternating multilayer of vanadium pentoxide (V₂O₅), 25 nm, and vanadium (V), 5 nm, thin films deposited at room temperature by radio frequency (RF) and DC magnetron sputtering, respectively. Raman and photoluminescence (PL) spectroscopy have been employed to investigate the effects of thermal annealing for 20, 30 and 40 min at 400${}^{\circ }$C in Nitrogen (N₂) atmosphere on the multiple phase formation and its impact on the film resistance and temperature coefficient of resistance (TCR). We demonstrate that the oxygen free annealing environment allows the formation of multiple phases including V₂O₅, V₆O${}_{13}$ and VO₂ through oxygen diffusion and consequent deficiency in V₂O₅ layer.

Vanadium oxide thin films were grown on glass substrates using spray pyrolysis technique. The effects of substrate temperature, vanadium concentration in the initial solution and the solution spray rate on the nanostructural and the electrochromic properties of deposited films are investigated. Characterization and the electrochromic measurements were carried out using X-ray diffraction, scanning electron microscopy and cyclic voltammogram. XRD patterns showed that the prepared films have polycrystalline structure and are mostly mixed phases of orthorhombic α-V₂O₅ along with minor β-V₂O₅ and V₄O₉ tetragonal structures. The preferred orientation of the deposited films was found to be along [101] plane. The cyclic voltammogram results obtained for different samples showed that only the films with 0.2 M solution concentration, 5 ml/min solution spray rate and 450°C substrate temperature exhibit two-step electrochromic properties. The results show a correlation between cycle voltammogram, morphology and resistance of the films.

In this paper, S-doped vanadium oxide thin films with doping levels up to 40 at.% are prepared via spray pyrolysis method on glass substrates, and the effect of S-doping on the structural and photoconductivity related properties of $\beta$-V₂O₅ thin films is studied. The results show that most of the films have been grown in the tetragonal $\beta$-V₂O₅ phase structure with the preferred orientation along [200]. With increasing the doping level, the samples tend to be amorphous. The structure of the samples reveals to be nanobelt-shaped whose width decreases from nearly 100 nm to 40 nm with S concentration. The photoconductivity measurements show that by increasing the S-doping level, the photosensitivity increases, which is due to the prolonged electron’s lifetime as a result of enhanced defect states acting as trap levels.

Polycrystalline vanadium oxide (VO_x) thin films with mixed phases of V₆O₁₃ + VO₂ (M) are deposited onto p-doped Si (100) substrates at 430°C using magnetron sputtering. By vacuum annealing on as-deposited VO_x thin films at 450°C, at different annealing times we obtained nanoscale polycrystalline VO_x thin films with two or more mixed phases. With the annealing time increasing, the phases of the films underwent the following transformation: V₆O₁₃ + VO₂ (M) → VO₂ (M) + VO₂ (B) → VO₂ (B) + VO₂ (M) + V₅O₉ → V₄O₇ + V₅O₉. The surface of VO_x thin films prepared in different conditions is of high quality with mean grain size ranging from 80 to 300 nm and the R_a being about 20nm. The lowest temperature coefficient of resistance at ambient temperature (20°C) of -2% K^-1 is found in the VO_x thin film annealed at 450°C for 8 h with mixed phases of VO₂ (M) + VO₂ (B), which can meet the needs of microbolometer materials.

Ordered mesoporous carbon film supporting vanadium oxide nanoparticles has been synthesized via ultrasound-assistant impregnation method with ordered mesoporous carbon C-FDU15 film as the host and V₂O₅ sol as the guest precursor. The hybrids exhibit type IV sorption isotherms with H2 hysteresis loop, indicating the well-retained characteristics of ordered mesoporous structure. The capacitance of the materials is enhanced with V₂O₅ loading. Particularly, the hybrids with 32.26 wt.% V₂O₅ loading yield an important capacitance of 128 F/g in 1 mol/L KNO₃ electrolyte under a potential range from -0.6 V to 0.6 V. The improved specific capacitance of the hybrids is proposed to be the combination of the double-layer capacitance of ordered porous structure and the pseudocapacitance derived from V₂O₅.

Vanadium oxides, such as V₆O${}_{13}$, have a high theoretical capacity for sodium storage, but their performance faces the challenges of low conductivity and poor cycling stability caused by side reactions. To solve these problems, we report on the material design of self-supported nanosheet arrays coated with poly(3, 4-ethylenedioxythiophene) (PEDOT). In this design, the nanosheet architecture facilitates the electron and ion transport to boost the charge storage, while the PEDOT coating prevents the direct contact between the electrode nanosheet and the electrolyte, thus inhibiting the occurrence of side reactions. This PEDOT-modified nanosheet electrode exhibits a reversible capacity of 179 mAh g${}^{-1}$ in the potential range of 1.5–3.8 V, and retains 66% of the initial capacity at a rate of 1 C for 100 cycles.