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

ACS Comb Sci. 2013 Jun 10;15(6):309-19. doi: 10.1021/co400027p. Epub 2013 May 28.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Atmospheric Pressure
  • Catalysis
  • Combinatorial Chemistry Techniques / instrumentation
  • Combinatorial Chemistry Techniques / methods*
  • Equipment Design
  • Glass / chemistry*
  • Hydrophobic and Hydrophilic Interactions
  • Light*
  • Microscopy, Electron, Scanning
  • Nanostructures / chemistry*
  • Oxides / chemistry*
  • Phase Transition
  • Photochemical Processes
  • Spectrophotometry, Ultraviolet
  • Spectrum Analysis, Raman
  • Surface Properties
  • Titanium / chemistry*
  • Vanadium Compounds / chemistry*
  • Volatilization
  • X-Ray Diffraction

Substances

  • Oxides
  • Vanadium Compounds
  • vanadium dioxide
  • titanium dioxide
  • Titanium