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Title: Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions

Abstract

Artificial photosynthetic devices are potential fuel sources. The basic idea in the design of such devices is a photosensitized electron-transfer that yields chemical species capable of reducing and oxidizing water to hydrogen and oxygen. A fundamental difficulty in effecting this transfer is the thermodynamically favored back reactions of the intermediary redox species. An interfacial model composed of a water-in-oil microemulsion is suggested to provide the separation of these redox species, thereby preventing back-reactions. This model is designed to accomplish the photodecomposition of water in two separate water-in-oil microemulsions coupled by a redox reaction. Phase-transfer of one of the redox products from the water-in-oil interface to the continuous organic phase is the principle by which separation is achieved. The oxidation and reduction sites of the general model have been constructed. One system includes the photosensitized oxidation of a donor, EDTA, solubilized in the water pool, benzylnicotinamide acts as a primary acceptor that mediates by the phase transfer principle the reduction of a secondary acceptor, dimethylamino-azobenzene, solubilized in the continuous organic phase. In system two, involving the photosensitized reduction of methyl viologen, by tris(2,2'bipyridine)Ru(2+), thioophenol is used as the donor and its oxidation product is phase transferred to the continuous organic phase.more » The photoinduced processes accomplished in the two systems proceed along an uphill gradient of free energy. Two water soluble zinc-porphyrins can substitute for the Ru(2+) complex in the second system. As the two Zn-porphyrins are oppositely charged, the effect of electrostatic interactions on the quantum yields of viologen reduction could be evaluated. The results suggest that the surface charge of the wateroil interface strongly influences the efficiency of electron-transfer.« less

Authors:
; ;
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
OSTI Identifier:
5140968
Report Number(s):
LBL-11232; CONF-8006111-1
DOE Contract Number:  
W-7405-ENG-48
Resource Type:
Conference
Resource Relation:
Conference: 10. North Eastern regional meeting of the American Chemical Society, Potsdam, NY, USA, 29 Jun 1980
Country of Publication:
United States
Language:
English
Subject:
14 SOLAR ENERGY; 08 HYDROGEN; HYDROGEN PRODUCTION; BIOMIMETIC PROCESSES; MICROEMULSIONS; PHOTOCHEMICAL REACTIONS; PHOTOSYNTHESIS; SOLAR ENERGY CONVERSION; BIPYRIDINES; EFFICIENCY; ELECTRON TRANSFER; HYDROGEN; INTERFACES; OILS; OXIDATION; OXYGEN; PORPHYRINS; REDOX REACTIONS; REDUCTION; RUTHENIUM COMPLEXES; SENSITIZERS; WATER; ZINC COMPLEXES; AZINES; CARBOXYLIC ACIDS; CHEMICAL REACTIONS; COLLOIDS; COMPLEXES; CONVERSION; CRYOGENIC FLUIDS; DISPERSIONS; ELEMENTS; EMULSIONS; ENERGY CONVERSION; FLUIDS; HETEROCYCLIC ACIDS; HETEROCYCLIC COMPOUNDS; HYDROGEN COMPOUNDS; NONMETALS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; OTHER ORGANIC COMPOUNDS; OXYGEN COMPOUNDS; PYRIDINES; REAGENTS; SYNTHESIS; TRANSITION ELEMENT COMPLEXES; 140505* - Solar Energy Conversion- Photochemical, Photobiological, & Thermochemical Conversion- (1980-); 080106 - Hydrogen- Production- Biosynthesis & Photochemical Processes

Citation Formats

Willner, I, Otvos, J W, and Calvin, M. Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions. United States: N. p., 1980. Web.
Willner, I, Otvos, J W, & Calvin, M. Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions. United States.
Willner, I, Otvos, J W, and Calvin, M. 1980. "Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions". United States. https://www.osti.gov/servlets/purl/5140968.
@article{osti_5140968,
title = {Vectorially photoinduced electron-transfer processes across water-in-oil interfaces of microemulsions},
author = {Willner, I and Otvos, J W and Calvin, M},
abstractNote = {Artificial photosynthetic devices are potential fuel sources. The basic idea in the design of such devices is a photosensitized electron-transfer that yields chemical species capable of reducing and oxidizing water to hydrogen and oxygen. A fundamental difficulty in effecting this transfer is the thermodynamically favored back reactions of the intermediary redox species. An interfacial model composed of a water-in-oil microemulsion is suggested to provide the separation of these redox species, thereby preventing back-reactions. This model is designed to accomplish the photodecomposition of water in two separate water-in-oil microemulsions coupled by a redox reaction. Phase-transfer of one of the redox products from the water-in-oil interface to the continuous organic phase is the principle by which separation is achieved. The oxidation and reduction sites of the general model have been constructed. One system includes the photosensitized oxidation of a donor, EDTA, solubilized in the water pool, benzylnicotinamide acts as a primary acceptor that mediates by the phase transfer principle the reduction of a secondary acceptor, dimethylamino-azobenzene, solubilized in the continuous organic phase. In system two, involving the photosensitized reduction of methyl viologen, by tris(2,2'bipyridine)Ru(2+), thioophenol is used as the donor and its oxidation product is phase transferred to the continuous organic phase. The photoinduced processes accomplished in the two systems proceed along an uphill gradient of free energy. Two water soluble zinc-porphyrins can substitute for the Ru(2+) complex in the second system. As the two Zn-porphyrins are oppositely charged, the effect of electrostatic interactions on the quantum yields of viologen reduction could be evaluated. The results suggest that the surface charge of the wateroil interface strongly influences the efficiency of electron-transfer.},
doi = {},
url = {https://www.osti.gov/biblio/5140968}, journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Jul 01 00:00:00 EDT 1980},
month = {Tue Jul 01 00:00:00 EDT 1980}
}

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