title: Combinatorial atmospheric pressure chemical vapor deposition of graded TiO₂-VO₂ mixed-phase composites and their dual functional property as self-cleaning and photochromic window coatings.
abstract: A combinatorial film with a phase gradient from V:TiO₂ (V: Ti ≥ 0.08), through a range of TiO₂-VO₂ composites, to a vanadium-rich composite (V: Ti = 1.81) was grown by combinatorial atmospheric pressure chemical vapor deposition (cAPCVD). The film was grown from the reaction of TiCl₄, VCl₄, ethyl acetate (EtAc), and H₂O at 550 °C on glass. The gradient in gas mixtures across the reactor induced compositional film growth, producing a single film with numerous phases and compositions at different positions. Seventeen unique positions distributed evenly along a central horizontal strip were investigated. The physical properties were characterized by wavelength dispersive X-ray (WDX) analysis, X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), and UV-visible spectroscopy. The functional properties examined included the degree of photoinduced hydrophilicity (PIH), UVC-photocatalysis, and thermochromism. Superhydrophilic contact angles could be achieved at all positions, even within a highly VO₂-rich composite (V: Ti = 1.81). A maximum level of UVC photocatalysis was observed at a position bordering the solubility limit of V:TiO₂ (V: Ti ≈ 0.21) and fragmentation into a mixed-phase composite. Within the mixed-phase TiO₂: VO₂ composition region (V: Ti = 1.09 to 1.81) a decrease in the semiconductor-to-metal transition temperature of VO₂ from 68 to 51 °C was observed.
authors.affiliation: Materials Chemistry Research Centre, Department of Chemistry, University College London, 20 Gordon Street, London, UK WC1H 0AJ.
authors.forename: Mia
authors.initials: M
authors.lastname: Wilkinson
authors.forename: Andreas
authors.initials: A
authors.lastname: Kafizas
authors.forename: Salem M
authors.initials: SM
authors.lastname: Bawaked
authors.forename: Abdullah Y
authors.initials: AY
authors.lastname: Obaid
authors.forename: Shaeel A
authors.initials: SA
authors.lastname: Al-Thabaiti
authors.forename: Sulaiman N
authors.initials: SN
authors.lastname: Basahel
authors.forename: Claire J
authors.initials: CJ
authors.lastname: Carmalt
authors.forename: Ivan P
authors.initials: IP
authors.lastname: Parkin
mesh_terms: D001274:Atmospheric Pressure; D002384:Catalysis; D020650:Combinatorial Chemistry Techniques / Q000295:instrumentation / Q000379:methods*; D004867:Equipment Design; D005898:Glass / Q000737:chemistry*; D057927:Hydrophobic and Hydrophilic Interactions; D008027:Light; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D044367:Phase Transition; D055668:Photochemical Processes; D013056:Spectrophotometry, Ultraviolet; D013059:Spectrum Analysis, Raman; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*; D017968:Vanadium Compounds / Q000737:chemistry*; D014835:Volatilization; D014961:X-Ray Diffraction
chemical_list: D010087:Oxides; D017968:Vanadium Compounds; C581824:vanadium dioxide; C009495:titanium dioxide; D014025:Titanium