Polyelectrolyte-stabilized metal oxide hydrosols as catalysts for the photooxidation of water by zinc porphyrins
Colloids of ruthenium dioxide and iridium oxide have been prepared and characterized. These colloids, which are inherently negatively charged in neutral water, have been stabilized with a surface layer of polyelectrolyte. Electrostatic binding occurs between the stabilized colloids and water-soluble zinc porphyrins of the opposite electronic charge. Such electrostatic forces affect the rate constant for interfacial electron transfer between the colloids and radical cations derived from the zinc porphyrins. The products of these reactions depend upon the relative charges of the reactants. For oppositely charged reactants, the rate of interaction was very high but O/sub 2/ generation was not observed. In some cases where the porphyrin and colloid possess the same charge, the system can be used to oxidize water to O/sub 2/ under photochemical conditions. The yield of O/sub 2/ depends upon the solution pH and the nature of both reactants. With negatively charged reactions in alkaline solution, the authors have reported quantum efficiencies for O/sub 2/ generation in the range of 50-60%. With positively charged reactants, oxygen formation could be observed in acidic solution, although the quantum efficiencies were less than 10%.
- Research Organization:
- National Bureau of Standards, Gaithersburg, MD (USA)
- OSTI ID:
- 6253952
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 92:15
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
IRIDIUM OXIDES
CATALYTIC EFFECTS
PORPHYRINS
PHOTOCHEMICAL REACTIONS
RUTHENIUM OXIDES
WATER
ZINC COMPOUNDS
CATALYSIS
ELECTROLYTES
EXPERIMENTAL DATA
OXIDATION
POLYMERS
SOLS
CARBOXYLIC ACIDS
CHALCOGENIDES
CHEMICAL REACTIONS
COLLOIDS
DATA
DISPERSIONS
HETEROCYCLIC ACIDS
HETEROCYCLIC COMPOUNDS
HYDROGEN COMPOUNDS
INFORMATION
IRIDIUM COMPOUNDS
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
REFRACTORY METAL COMPOUNDS
RUTHENIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
400500* - Photochemistry