Investigation of DC magnetron-sputtered TiO2 coatings: Effect of coating thickness, structure, and morphology on photocatalytic activity

Svava Daviðsdóttir, Rajashekhara Shabadi, Aurelian Catalin Galca, Inge Hald Andersen, Kai Dirscherl, Rajan Ambat

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Abstract

The photocatalytic performance of magnetron-sputtered titanium dioxide (TiO2) coatings of different thickness in anatase crystalline structure deposited on aluminium 1050 alloy substrates was investigated using a combination of photo-electrochemistry, methylene blue decomposition, and microscopic and spectroscopic methods, such as high resolution scanning and transmission electron microscopy, atomic force microscopy and ellipsometry. The reaction resistance was measured by AC impedance, while photocurrent measurements were carried out using the zero resistance ammetry (ZRA) method. The results showed that the TiO2 grains grow in dipyramidal columns having a linear increase in surface area with increased coating thickness. The refractive index values indicate also an evolutionary growth.
The refractive index values obtained for the thin coatings on aluminium substrate were well below the values reported for monocrystalline anatase. The photocatalytic performance increased with increased coating thickness, though more rapidly over a range of 100 - 500 nm thickness. The dielectric constant also increased linearly with coating thickness.
Original languageEnglish
JournalApplied Surface Science
Volume313
Pages (from-to)677–686
ISSN0169-4332
DOIs
Publication statusPublished - 2014

Keywords

  • Photocatalysis
  • TiO2
  • Coatings
  • Magnetron-sputtering
  • Electrochemical impedance spectroscopy

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