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

Journal Article · Thu Jul 15 04:00:00 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), Journal Name: Journal of Physical Chemistry; (United States) Vol. 97:28; ISSN JPCHAX; ISSN 0022-3654
• Country of Publication: United States
• Language: English

Related Subjects

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