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Nanostructured TiO2 anatase-rutile-carbon solid coating with visible light antimicrobial activity

Authors
  • Krumdieck, Susan P.1
  • Boichot, Raphaël2
  • Gorthy, Rukmini1
  • Land, Johann G.1
  • Lay, Sabine2
  • Gardecka, Aleksandra J.1
  • Polson, Matthew I. J.3
  • Wasa, Alibe4
  • Aitken, Jack E.4
  • Heinemann, Jack A.4
  • Renou, Gilles2
  • Berthomé, Grégory2
  • Charlot, Frédéric2
  • Encinas, Thierry2
  • Braccini, Muriel2
  • Bishop, Catherine M.1
  • 1 University of Canterbury, Advanced Energy and Material Systems Laboratory, Department of Mechanical Engineering, Christchurch, 8041, New Zealand , Christchurch (New Zealand)
  • 2 Univ. Grenoble Alpes, CNRS, Grenoble INP (Institute of Engineering), SIMAP, Grenoble, F-38000, France , Grenoble (France)
  • 3 University of Canterbury, Department of Chemistry, Christchurch, 8041, New Zealand , Christchurch (New Zealand)
  • 4 University of Canterbury, School of Biological Sciences, Christchurch, 8041, New Zealand , Christchurch (New Zealand)
Type
Published Article
Journal
Scientific Reports
Publisher
Springer Nature
Publication Date
Feb 13, 2019
Volume
9
Issue
1
Identifiers
DOI: 10.1038/s41598-018-38291-y
Source
Springer Nature
License
Green

Abstract

TiO2 photocatalyst is of interest for antimicrobial coatings on hospital touch-surfaces. Recent research has focused on visible spectrum enhancement of photocatalytic activity. Here, we report TiO2 with a high degree of nanostructure, deposited on stainless steel as a solid layer more than 10 μm thick by pulsed-pressure-MOCVD. The TiO2 coating exhibits a rarely-reported microstructure comprising anatase and rutile in a composite with amorphous carbon. Columnar anatase single crystals are segmented into 15–20 nm thick plates, resulting in a mille-feuilles nanostructure. Polycrystalline rutile columns exhibit dendrite generation resembling pine tree strobili. We propose that high growth rate and co-deposition of carbon contribute to formation of the unique nanostructures. High vapor flux produces step-edge instabilities in the TiO2, and solid carbon preferentially co-deposits on certain high energy facets. The equivalent effective surface area of the nanostructured coating is estimated to be 100 times higher than standard TiO2 coatings and powders. The coatings prepared on stainless steel showed greater than 3-log reduction in viable E coli after 4 hours visible light exposure. The pp-MOCVD approach could represent an up-scalable manufacturing route for supported catalysts of functional nanostructured materials without having to make nanoparticles.

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