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<p>In the present work, vanadium pentoxide (V<sub>2</sub>O<sub>5</sub>) and graphene oxide (GO) nanocomposites (V<sub>2</sub>O<sub>5</sub>–GO) of mixed weight percent (wt%) (V<sub>2</sub>O<sub>5</sub>: GO at 1:1 (a), 5:1 (b) and 10:1 (c)) are synthesized and thermally annealed at 400&#xa0;°C, 500&#xa0;°C and 600&#xa0;°C in the presence of nitrogen. Structural and optical properties are studied in details using X-ray diffraction (XRD), UV–VIS (ultraviolet–visible), Raman and FTIR (Fourier transform infrared) spectroscopies. X-ray diffraction studies on the annealed samples show the presence of various characteristic peaks corresponding to orthorhombic V<sub>2</sub>O<sub>5</sub> phase along with other polymorphs of VO<sub>2</sub> (monoclinic VO<sub>2</sub> (M) (peaks at 2θ = 27.8°, 33.35°, 36.99°), VO<sub>2</sub> (A) (peak at 2θ = 25.45°), and VO<sub>2</sub> (B) (peak at 2θ = 26.12°)). Peak at 2θ = 24.12° due to the presence of graphene XRD is seen which broadens with decreasing content of V<sub>2</sub>O<sub>5</sub> at higher annealing temperature. To further confirm various phases of V<sub>2</sub>O<sub>5</sub> and VO<sub>2</sub> we have studied Raman spectroscopy. The study shows the existence of V<sub>2</sub>O<sub>5</sub> vibrational modes at 697&#xa0;cm<sup>−1</sup> and 997&#xa0;cm<sup>−1</sup>, and VO<sub>2</sub> vibrational modes at 930&#xa0;cm<sup>−1</sup>, 880&#xa0;cm<sup>−1</sup>, 441&#xa0;cm<sup>−1</sup> and 395&#xa0;cm<sup>−1</sup>. UV–VIS absorption studies show reduction in energy band gap of the annealed samples which is attributed to the possible conversion of V<sub>2</sub>O<sub>5</sub> to VO<sub>2</sub>. UV–VIS absorption and Raman spectroscopic studies are, thus, in agreement with the X-ray diffraction studies indicating possible conversion of V<sub>2</sub>O<sub>5</sub> to VO<sub>2</sub> and co-existence of both the phases, as supported further by Energy dispersive X-ray (EDX) analysis. Thermochromic switching property of annealed samples is studied using FTIR spectroscopy which shows considerable switching in the optical transmission (Δ (%Transmission) ≈ 10–20%) when measured at room temperature and 90&#xa0;°C.</p>

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Effect of thermal annealing on the composition, structure and optical properties of V2O5–GO nanocomposites

  • 期刊论文

  • 发表日期：

    2025年1月6日

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  • Shraddha Shukla,
  • Urvashi Solanki,
  • Akanksha Yadav,
  • Anil K. Yadav,
  • P. Mandal

摘要

In the present work, vanadium pentoxide (V2O5) and graphene oxide (GO) nanocomposites (V2O5–GO) of mixed weight percent (wt%) (V2O5: GO at 1:1 (a), 5:1 (b) and 10:1 (c)) are synthesized and thermally annealed at 400 °C, 500 °C and 600 °C in the presence of nitrogen. Structural and optical properties are studied in details using X-ray diffraction (XRD), UV–VIS (ultraviolet–visible), Raman and FTIR (Fourier transform infrared) spectroscopies. X-ray diffraction studies on the annealed samples show the presence of various characteristic peaks corresponding to orthorhombic V2O5 phase along with other polymorphs of VO2 (monoclinic VO2 (M) (peaks at 2θ = 27.8°, 33.35°, 36.99°), VO2 (A) (peak at 2θ = 25.45°), and VO2 (B) (peak at 2θ = 26.12°)). Peak at 2θ = 24.12° due to the presence of graphene XRD is seen which broadens with decreasing content of V2O5 at higher annealing temperature. To further confirm various phases of V2O5 and VO2 we have studied Raman spectroscopy. The study shows the existence of V2O5 vibrational modes at 697 cm−1 and 997 cm−1, and VO2 vibrational modes at 930 cm−1, 880 cm−1, 441 cm−1 and 395 cm−1. UV–VIS absorption studies show reduction in energy band gap of the annealed samples which is attributed to the possible conversion of V2O5 to VO2. UV–VIS absorption and Raman spectroscopic studies are, thus, in agreement with the X-ray diffraction studies indicating possible conversion of V2O5 to VO2 and co-existence of both the phases, as supported further by Energy dispersive X-ray (EDX) analysis. Thermochromic switching property of annealed samples is studied using FTIR spectroscopy which shows considerable switching in the optical transmission (Δ (%Transmission) ≈ 10–20%) when measured at room temperature and 90 °C.