Growth stages of nano-structured mixed-phase titania thin films and effect on photocatalytic activity

Aleksandra J. Gardecka, Matthew I. J. Polson, Susan P. Krumdieck, Yicun Huang, Catherine M. Bishop

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

The development of nano-structured mixed-phase titania thin films and the relationship to photocatalytic activity (PCA) is of interest for pollution reduction and antimicrobial applications. A set of films grown by pulsed pressure metallorganic chemical vapour deposition using titanium tetraisopropoxide precursor was studied. The growth method is single-stage, scalable and produces high-quality, adherent films. Film thicknesses were 101 nm to 4.0 μm. Three growth stages were identified. All films were a mixture of anatase and rutile. Early stage films had rounded morphologies, low surface roughness and low PCA. Transition stage films developed columnar [110] orientated anatase dendrites, contained amorphous carbon and had reduced UV transmittance. Late stage films had strong anatase (220) and rutile (200) textures, contained amorphous carbon and exhibited highly branched anatase dendrites with nanoscale secondary plates. PCA was determined from degradation of stearic acid and correlated with increasing surface roughness. The most active film had formal quantum efficiency of (6.62 ± 0.64) × 10−4 molecules/photon, 59 times higher than a commercially available control. The performance is attributed to the combination of phases yielding polymorphic phase boundaries and amorphous carbon enhancing the adsorption of organic molecules, the unusual (220) anatase texture yielding nanostructured anatase dendrites in combination with nanocrystalline rutile and hierarchical porosity.

Original languageEnglish
Pages (from-to)136-144
Number of pages9
JournalThin Solid Films
Volume685
Early online date14 Jun 2019
DOIs
Publication statusPublished - 1 Sep 2019

Keywords

  • Film development
  • Hierarchical porosity
  • Photocatalysis
  • Pulsed pressure metal-organic chemical vapour deposition
  • Surface roughness
  • Titania

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Surfaces and Interfaces
  • Surfaces, Coatings and Films
  • Metals and Alloys
  • Materials Chemistry

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