Commercialisation of Chemistry Visible light semiconductor photocatalysts

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Commercialisation of ChemistryVisible light
semiconductor photocatalysts a novel hygiene
solution

• Declan McCormack (DIT) and Robert Hickson
  (Vitra)

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Titania (TiO2)
Nafion
Precipitation of submicron high surface area
seconducting titania as a support for metal oxide
anodic catalysts, mainly for fuel cells.
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Ignatz Semmelweis (1818-1865)
1847- Childbed (Puerperal) Fever in Vienna
Hospital Obstetrical Clinic
cadaverous particles
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Hospital Superbugs

• 75 of the total 8,000 cases of hospital acquired
  infections (HAI) were due to the superbug MRSA
  (Methicillin Resistant Staphylococcus Aureus) in
  Ireland. Other more virulent strains such as KPC
  NDM-1
• Annual cleaning bills for Irish hospitals are 68
  million and the total economic burden of hospital
  acquired infection is over 150 million every
  year.
• The proportion of MRSA observed in Ireland is one
  of the highest in Europe

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A familiar photocatalyst product in the market
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How the titania coating in Pilkington glass works
as a superhydrophilic coating?
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Visible light active titania
Visible light active TiO2 EBG lt 3.2eV
Conventional TiO2 EBG 3.2eV
R. Asahi, T. Morikawa, T. Ohwaki, K. Aoki, Y.
Taga, Science. 2001, 293, 269.
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First N-doped Titania (TiO2)
Asahi (2001)

• TiO2-xNx prepared by sputtering with N2 and
  annealing in N2 atmosphere at 550 oC
• Mixture of anatase and rutile
• Yellow transparent films

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Doping with non-metal ions

• Fluorine (In collaboration with JM Kelly and I
  Gunko, TCD)
• Chem. Mater., 19 (18), 2007, 4474-4481.
• Nitrogen
• J. Phys. Chem. C, 111(4), 2007, 16051611.
• Sulphur
• J. Phys. Chem. C, 112 (20), 2008, 447652.
• Nitrogen and Sulphur
• J. Phys. Chem. C, 113,(8),2009, 3246-3253.  
• Nitrogen doped heterojunctions
• Chem. Mater., 22, 2010, 38433853

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Challenge Anatase to Rutile Transformation

• 600 to 700 C in pure titania

600- 700 C
Anatase (Edge shared)
Rutile (Corner shared)
Photocatalytic Phase
Non-Photocatalytic Phase
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How a delayed phase transition happens
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Effect of S- doping
J. Phys. Chem. C, 112 (20), 2008, 447652.
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Sunlight Driven Photocatalysis- 850OC calcined
samples
(a) Control sample 210 minutes
J. Phys. Chem. C, 112 (20), 2008, 447652.
(b) S-doped sample 35 minutes
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Mechanism of doping
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A Photocatalytic Tile?

• High temperature stable anatase phase (above
  1000OC)
• Visible light activity by doping
• A stable anatase phase up to the sintering
  temperature of the ceramic substrates is most
  desirable for applications on anti-bacterial
  ceramic materials (e.g. bathroom tile, sanitary
  ware etc.).

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Anti-bacterial Ceramic Tiles- Challenges

• High Sintering temperature (above 1000OC).
• Photocatalytic phase anatase change to rutile at
  600O to 700OC
• High temperature stability and visible light
  activity are requisite

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Examples of RADICALs anti-bacterials
Photocatalyst products
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Turkish Trials
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Anti-bacterial Tiles
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Anti-MRSA High Tc Tiles
Anti-MRSA test of titania samples (a) control (b)
CREST TiO2
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External Antimicrobial Testing against E. coli
Airmid healthgroup , using ISO 27447 2009
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Conclusions

• A novel industrial viable technology has been
  developed to prepare visible light active
  titania.
• A high temperature stable photo-active titania
  has been developed
• Anti-MRSA ceramic tiles have been produced
• Industrial pilot plant operation has been
  successfully carried out.

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Enterprise Ireland ARE programme

Dr Suresh Pillai Dr John Colreavy Dr Hugh
Hayden Mr Darragh Ryan Dr Pradeepan Periyat Dr
Michael Seery
12/26/2013