Photochemical conversion of solar energy. Annual report, January 1, 1975--December 31, 1975. [Iron--thiazine and iron--thionine]
Totally illuminated-multi thin layer (TL-MTL) iron-thiazine photogalvanic cells with SnO/sub 2/ anodes and InSnO/sub 2/ cathodes were constructed. A 0.07 percent sunlight engineering efficiency for power conversion was obtained with a 4-element TI-MTL iron-thionine cell with 80 ..mu..m electrode spacing. Output from the elements of a 2-layer cell with iron-thionine in one element and iron-methylene blue in the other was additive. The quantum yield for current conversion of TI-TL SnO/sub 2//Pt iron-thionine cells was more than doubled when electrode spacing was reduced from 80 ..mu..m to 25 ..mu..m. Thiazine dyes gave the best outputs of all electroactive dyes tested during 1975. Fe(H/sub 2/O)/sub 6//sup 2 +//Fe(H/sub 2/O)/sub 6//sup 3 +/ was the most effective inorganic redox couple. Output of iron-thionine TI-TL SnO/sub 2//Pt cells is not limited by electron transfer at electrode-solution interfaces. Ohmic resistance in the SnO/sub 2/ electrode and bulk back reaction in solution may both limit output. Leaching of tin is associated with irreversible degradation of SnO/sub 2/ electrodes by iron-thionine cell solution. Thionine and methylene blue are stable in cell solutions in 50 v/v percent aq. CH/sub 3/CN in the dark in the absence of air but degrade in sunlight. Solutions in water are stable under the latter conditions. Rate constants for unimolecular decay of triplet thionine and methylene blue for their reaction with Fe(II), for their quenching by ground state dyes or Fe(III) and for the bulk back reactions of leucothionine, leucomethylene blue and semithionine with Fe(III) were measured under a variety of conditions. Composition and kinetics of relaxation of the photochemical steady state were measured under various cell conditions and correlated with the above rate measurements and with cell output. The quantum yield for photodecomposition of FeBr/sub 3/ in acidic aqueous solution was found to be constant from 366 to 578 nm.
- Research Organization:
- Boston Univ., Mass. (USA). Dept. of Chemistry
- OSTI ID:
- 5358517
- Report Number(s):
- NSF/RANN/SE/AER-72-03579/A03/75/4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
PHOTOGALVANIC CELLS
PERFORMANCE TESTING
RESEARCH PROGRAMS
AQUEOUS SOLUTIONS
AZINES
CHEMICAL REACTION KINETICS
DECOMPOSITION
DYES
EFFICIENCY
ELECTROCHEMISTRY
ELECTRODES
INDIUM OXIDES
IRON
IRON BROMIDES
METHYLENE BLUE
PHOTOCHEMISTRY
REDOX REACTIONS
SENSITIZERS
SOLVENTS
THIONINE
TIN OXIDES
AMINES
BROMIDES
BROMINE COMPOUNDS
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
CHLORIDES
CHLORINE COMPOUNDS
DISPERSIONS
DRUGS
ELECTROCHEMICAL CELLS
ELEMENTS
HALIDES
HALOGEN COMPOUNDS
HETEROCYCLIC COMPOUNDS
INDIUM COMPOUNDS
IRON COMPOUNDS
KINETICS
METALS
MIXTURES
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
ORGANIC SULFUR COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
PHENOTHIAZINES
REACTION KINETICS
REAGENTS
SOLUTIONS
TESTING
TIN COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
140505* - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)