What makes a good TiO2 photocatalyst?
2009 (English)In: Ceramic Engineering and Science Proceedings, Wiley & Sons , 2009, 28, Vol. 29, no 8, 19-35 p.Chapter in book (Other academic)
Titanium dioxide pholocatalysis is an area which has witnessed an enormous progress during the past three decades. Applications of TiO2 photocatalysis include environmental remediation, self-cleaning coatings, and is also at the heart of TiO2 based energy production (H-2 and electricity). Despite an enormous literature a comprehensive understanding of the surface reaction steps on TiO2 is still lacking. This reflects both the complex nature of photocatalytic processes and the difficulties of studying nanoparticles. In this paper we present examples from combined in situ molecular spectroscopy studies that highlight the dependence of surface reaction of the structure of TiO2 nanoparticles. We show that for a broad class of organic molecules the reactivity is governed mainly by the bonding and reactivity of a few common intermediate species. The photocatalytic efficiency is correlated with the particle structure and elementary surface reactions steps. We show that p-formate is a common intermediate that control the overall photo-degradation rate of propane, ketones, and carboxylic acid on rutile TiO2 In contrast, on anatase TiO2 photo-oxidation of acetone is rate determining. This shows that the reactivity of TiO2 is sensitive to both surface modification and reactant molecule. Furthermore, the pholo-oxidation rate of formic acid depends on the detailed anatase surface properties. This is attributed to a balance of formate bonded to coordinately unsaturated surface (c.u.s.) Ti atoms and hydrogen bonded molecules due the different bonding strength of formate on c.u.s. sites present oil different crystal facets and defects. Ways to improve the surface reactivity of TiO2, nanoparticles are discussed.
Place, publisher, year, edition, pages
Wiley & Sons , 2009, 28. Vol. 29, no 8, 19-35 p.
METAL-OXIDE SURFACES; TITANIUM-DIOXIDE; HETEROGENEOUS PHOTOCATALYSIS; ROOM-TEMPERATURE; FORMIC-ACID; RUTILE TIO2; THIN-FILMS; ANATASE; TIO2(110); ADSORPTION
Engineering and Technology
IdentifiersURN: urn:nbn:se:uu:diva-139855ISI: 000264857300002OAI: oai:DiVA.org:uu-139855DiVA: diva2:382244