Qualitative XANES and XPS Analysis of Substrate Effects in VO₂ Thin Films: A Route to Improving Chemical Vapor Deposition Synthetic Methods?

Abstract

Vanadium(IV) oxide thin films were synthesised via Atmospheric Pressure Chemical Vapour Deposition by the reaction between vanadium(IV) chloride and ethyl acetate at 550 °C. The substrate was varied with films being deposited on glass, SnO2 and F-doped SnO2. The films were characterised by X-ray diffraction, X-ray photoelectron spectroscopy, UV/vis spectroscopy, scanning electron microscopy and X-ray absorption near-edge structure. The influence of the electronic contribution of the substrate on the deposited VO2 film was found to be key to the functional properties observed.Highly electron withdrawing substituents, such as fluorine, favoured the formation of V 5+ ions in the crystal lattice and so reduced the thermochromic properties. By considering both the structural and electronic contributions of the substrate, it is possible to establish the best substrate choices for the desired functional properties of the VO2 thin films synthesised.

One-step hydrothermal synthesis and thermochromic properties of chlorine-doped VO2(M) for smart window application

“…The presence of V 5þ species could be attributed to the oxidized vanadium at the surface of the sample exposed to air. 26,54,55 The similar profiles can be assigned for samples VO 2 (M)-Cl-10 and VO 2 (M)-Cl-15 shown in Figs. 4(e) and 4(f), respectively.…”

Tailoring Energy and Power Density through Controlling the Concentration of Oxygen Vacancies in V2O5/PEDOT Nanocable-Based Supercapacitors

“…The slight difference in the shape of the pre-edge feature and the precise edge position is a general behavior observed in nanoscale compounds . The reduced vanadium sites are described by V 4+ and V 3+ . − The XANES curves of V 2 O 5 -NF and V 5+ agree well in Figure S5c. A little shift in the edge position was observed in samples in 2 and 3 h in Figure d.…”

Room-temperature application of VO2 microstructures on rigid and flexible substrates based on synthesis of crystalline VO2 solution

“…The samples exhibit a V 2p 3/2 peak at B516.4 eV, which is associated with vanadium in the V 4+ oxidation state. [46][47][48][49][50][51][52][53] The O 1s peaks at B530 eV corresponds to V-O bonding, as indicated in the literature, 46,50,54 while 532 eV corresponds to oxygen atoms in the Si-O in the substrate. 55 These findings confirm that the grown crystals as well as the delaminated samples that have been drop-cast on glass substrates for analysis are indeed VO 2 .…”