Photoelectrochemistry in particulate systems. 9. Photosensitized reduction in a colloidal TiO sub 2 system using anthracene-9-carboxylic acid as the sensitizer

Journal Article · Thu Jan 26 04:00:00 EST 1989 · Journal of Physical Chemistry; (USA)

DOI:https://doi.org/10.1021/j100339a062· OSTI ID:5447046

Kamat, P V ^[1]

---

1. Univ. of Notre Dame, IN (USA)

Time-resolved laser flash photolysis and fluorescence quenching studies have been carried out to elucidate the processes of charge injection from the excited anthracene-9-carboxylic acid (9AC) into the conduction band of TiO{sub 2} semiconductor colloid and the reaction of sensitized TiO{sub 2} colloid with an electron acceptor. 9AC adsorbed strongly on colloidal TiO{sub 2} with an apparent association constant of 6450 M{sup {minus}1}, and its fluorescence emission was quenched by TiO{sub 2} colloid with an efficiency of 94%. Only the singlet excited state of 9AC was found to participate din the sensitization of TiO{sub 2} with a rate constant of 4.8 {times} 10{sup 8} s{sup {minus}1} for the process of charge injection into the conduction band of the semiconductor. Analysis of the transient absorption spectra confirmed the generation of cation radical (9AC{sup +{sm bullet}}), most of which decayed quickly by recombining with the injected charge. The rate constant for the back electron transfer was found to be 5.5 {times} 10{sup 7} s{sup {minus}1}. The small fraction of the injected charge ({approximately} 10%) that survived within the particle was used to reduce another substrate, N,N,N',N'-tetraethyloxonine. the quantum yield for such a sensitized reduction process was 0.015. The role of the sensitizer and the semiconductor in promoting the sensitized reduction process is described.

• OSTI ID: 5447046
• Journal Information: Journal of Physical Chemistry; (USA), Journal Name: Journal of Physical Chemistry; (USA) Vol. 93:2; ISSN 0022-3654; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400500* -- Photochemistry
ANTHRACENE
AROMATICS
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
COLLOIDS
CONDENSED AROMATICS
DATA
DECOMPOSITION
DISPERSIONS
ELECTRON TRANSFER
EXPERIMENTAL DATA
FLUORESCENCE
HYDROCARBONS
INFORMATION
LASERS
LUMINESCENCE
MATERIALS
NEODYMIUM LASERS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PARTICLES
PHOTOCHEMICAL REACTIONS
PHOTOLYSIS
REDUCTION
SEMICONDUCTOR MATERIALS
SOLID STATE LASERS
TITANIUM COMPOUNDS
TITANIUM OXIDES
TRANSITION ELEMENT COMPOUNDS