Trapped holes on TiO[sub 2] colloids studied by electron paramagnetic resonance

Journal Article · Thu Jul 15 00:00:00 EDT 1993 · Journal of Physical Chemistry; (United States)

DOI:https://doi.org/10.1021/j100130a026· OSTI ID:5784618

Micic, O I; Zhang, Y; Cromack, K R; Trifunac, A D; Thurnauer, M C ^[1]

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1. Argonne National Lab., IL (United States)

An electron paramagnetic resonance (EPR) study of paramagnetic species formed on band gap irradiation of TiO[sub 2] colloids, aqueous suspensions of anatase (Degussa P-25), and rutile (Aldrich) powders is reported. The EPR signals (observed at 6-200 K) of the trapped hole in all of these systems exhibit similar properties. Holes produced by band gap irradiation of a TiO[sub 2] colloid move from the oxygen lattice to the surface and are trapped directly on oxygen atoms bound to surface Ti[sup IV] atoms. The results obtained with TiO[sub 2] colloids prepared with oxygen-17 enriched water support the identification of trapped holes as an oxygen surface anion radical covalently bound to titanium atoms, Ti[sup IV]-O-Ti[sup IV]-O[sup [center dot]]. The intensity of the EPR signal from the hole trap is very sensitive to hydration and the total surface area available for chemical reactions. The EPR signal disappears with the addition of hole scavengers that are strongly bound to the surface, such as polyvinyl alcohol and KI. The signal obtained for trapped holes at 6-240 K is not the same as that of surface bound or free OH* radicals, since no change in the EPR line width was observed when D[sub 2]O was used for preparation of colloids instead of H[sub 2]O. 80 refs., 8 figs., 2 tabs.

• OSTI ID: 5784618
• Journal Information: Journal of Physical Chemistry; (United States), Vol. 97:28; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
HOLES
TRAPPING
TITANIUM OXIDES
ELECTRON SPIN RESONANCE
COLLOIDS
EXPERIMENTAL DATA
HEAVY WATER
ORGANIC POLYMERS
POTASSIUM IODIDES
RADICALS
RUTILE
ALKALI METAL COMPOUNDS
CHALCOGENIDES
DATA
DISPERSIONS
HALIDES
HALOGEN COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC PHOSPHORS
IODIDES
IODINE COMPOUNDS
MAGNETIC RESONANCE
MATERIALS
MINERALS
NUMERICAL DATA
ORGANIC COMPOUNDS
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
PHOSPHORS
POLYMERS
POTASSIUM COMPOUNDS
RADIOACTIVE MATERIALS
RADIOACTIVE MINERALS
RESONANCE
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
WATER
400201* - Chemical & Physicochemical Properties
400102 - Chemical & Spectral Procedures