Synthesis of doubly functional nanowhiskers from a colloid solution including a V–Ti complex precursor

Abstract

In this study, we synthesized vanadium (V) nanoparticles precursor (NH 4 ) 5 [(VO) 6 (CO 3 ) 4 (OH) 9 ]Á10H 2 O a two-phase system of toluene and water. Colloid solution including titanium(IV) isopropoxide and polyvinylpyrrolidone (PVP) was subsequently deposited onto the nanoparticles to form urchin-like structures in a toluene solution as the vanadium-titanium (V-Ti) complex precursor. Calcining the urchin-like precursor at 700°C generated nanowhiskers of the Ti/V oxide complex after annealing process. These nanowhiskers were characterized using transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron microscopy (XPS). Films of the Ti/V oxide nanowhisker structure exhibited good visible transparency and a large change in transmittance at near-infrared (NIR) wavelengths before and after the metal-insulator phase transition. For a 44-nm-thick single-layer nanowhisker thin film, the transmittances at 700 nm in the metallic (M) and semiconductive (S) states were 75 and 72.2 %, respectively; the NIR switching efficiency (DT 2000 ) increased from 17 to 21.3 % at 2000 nm under UV light irradiation. In addition, the nanowhisker thin film of the Ti/V oxide complex significantly enhanced the photodecomposition of methylene blue under UV irradiation, relative to that of the unmodified TiO 2 . The dual functions of this material-thermochromicity and photocatalytic behavior-suggest that it might have interesting applications in energy-saving smart windows.

Effect of W-Mo doping on the phase transition temperature of VO2 synthesized by hydrothermal microwave method

“…The O1s and V2p spectra of the two samples were shown in figures 6(c) and 7(c), respectively. The phase of vanadium oxide could typically be determined based on the location of the distinctive V2p3/2 peak, as this is the position most sensitive to the phase transition [41]. As indicated in figures 6(c) and 7(c), the V 2p nuclear peaks in both samples were well-matched to the V 4+ state, indicating that the chemical valence was well-controlled [42].…”

Heteroepitaxial TiO2@W-doped VO2 core/shell nanocrystal films: preparation, characterization, and application as bifunctional window coatings

“…In the eld of VO 2 -based thermochromic smart windows, TiO 2 is also an important composite layer because of its good compatibility and crystalline structure similar to that of VO 2 . 5 It has been reported that TiO 2 lms are effective underneath layers or cover layers for inducing the crystallization of VO 2 (M/R), 6 constructing heterostructures for photoemission, 7,8 enhancing the oxidation durability, 9,10 regulating the phase transition properties, 11 and improving the optical performance of VO 2 . 1,12 Moreover, VO 2 (M)/TiO 2 composites have their own advantages, not only for increasing visible transmittance but also for modifying the infrared modulation ability.…”