Preparation of TiO2–based hollow microspheres by spray drying and their use as novel active pigments for photocatalytic coatings

Amado Velázquez-Palenzuela, Huan Wang, Nailiang Yang, Kim Dam-Johansen, Jakob Munkholt Christensen*

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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The use of TiO2 nanoparticles in organic-based photocatalytic coatings imposes several challenges: poor activity under visible light, binder photo-degradation, need for UV activation and toxicity concerns. Here we present a scalable two-step synthesis route to prepare TiO2-based hollow microspheres (HoS) as alternative photocatalyst to commercial TiO2 nanoparticles. The hollow microspheres of TiO2 or WO3-doped TiO2 (3 mol% WO3) are synthesized via template-assisted spray-drying followed by calcination. The structure and composition of the powders are characterized and their photocatalytic performance is assessed using methylene blue photo-degradation under UV irradiation as model reaction. XRD analysis reveals the presence of anatase and TiO2(B) phases, indicating the heterostructured nature of the samples. The results of the dye photo-degradation tests confirm the photocatalytic functionality of the TiO2-based HoS. Moreover, the introduction of WO3 (TiO2/WO3 HoS) leads to an enhancement of the performance, approaching that of commercial (Aeroxide P25, ~21 nm) nanoparticles. The most active TiO2/WO3 HoS are incorporated into an acrylic formulation and the resulting coatings tested towards pollutant abatement under UV light. A coating containing P25 nanoparticles undergoes an activation process where binder degradation leads to increased TiO2 exposure and a rise in catalytic activity but possibly at the expense of coating stability. By contrast TiO2/WO3 HoS-acrylic coatings exhibit catalytic activity similar to the initial activity of P25 containing coatings, but does not cause the same partial binder photo-degradation.

Original languageEnglish
Article number106518
JournalProgress in Organic Coatings
Number of pages11
Publication statusPublished - 2021


  • Acrylic coatings
  • Photocatalytic coatings
  • Pollution control
  • Spray-drying
  • TiO hollow microspheres


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