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Photosensitization of Crystalline and Amorphous Titanium Dioxide by Platinum( IV ) Chloride Surface Complexes
Author(s) -
Macyk Wojciech,
Kisch Horst
Publication year - 2001
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/1521-3765(20010504)7:9<1862::aid-chem1862>3.0.co;2-g
Subject(s) - anatase , platinum , chemistry , rutile , radical , photocatalysis , photochemistry , inorganic chemistry , amorphous solid , chloride , titanium dioxide , catalysis , materials science , organic chemistry , metallurgy
Anatase, rutile, and amorphous titania powders were surface‐modified by grinding with PtCl 4 and H 2 [PtCl 6 ]. Only the anatase modification afforded hybrid photocatalysts capable of degradation of 4‐chlorophenol (4‐CP) with visible light, with sufficient stability towards decomplexation. Grinding with K 2 [PtCl 4 ] produced materials of only low photocatalytic activity. Most efficient photocatalysts contained up to 2 wt % of Pt IV . At higher surface loading the excess fraction of the complex is desorbed into the aqueous solution. Scavenging experiments with benzoic acid and tetranitromethane revealed that hydroxyl radicals are produced by the primary reduction of oxygen by conduction band electrons generated through electron injection from a postulated surface platinum( III ) complex. It is proposed that the latter is formed from a charge‐transfer ligand‐to‐metal (CTLM) excited state through homolysis of the Pt−Cl bond. Accordingly, the primary oxidation of 4‐CP may occur by adsorbed chlorine atoms, the intermediary existence of which was demonstrated by scavenging experiments with phenol.