Photochemical energy storage: studies of inorganic photoassistance agents. Progress report, December 17, 1979-March 31, 1981
Research progress has been made in the study of p-type semiconductor (photocathode) electrode materials. A number of small band gap (E/sub g/ approximately equal to 1.1 to 1.4 eV) p-type semiconductors have been demonstrated to have poor H/sub 2/ evolution kinetics despite the fact that a reasonable output photovoltage (E/sub V/) compared to E/sub g/ could be expected. Special emphasis has been on p-type Si (E/sub g/ = 1.1 eV) and p-type InP (E/sub g/ = 1.35 eV). Both of these materials give poor kinetics for H/sub 2/ evolution from H/sub 2/O, while the kinetics for N,N'-dimethyl-4,4'-bipyridinium, MV/sup 2 +/, reduction to MV/sup +/ are good at a pH where E/sup 0/(H/sub 2/O/H/sub 2/) is the same as E/sup 0/(MV/sup 2+/+/). A surface derivatizing reagent from diquarternizing 4,4'-bipyridine with 1-bromo-3-trimethyloxysilylpropane can be used to functionalize p-type Si with polymeric quantities of redox reagent. The surface-confined bipyridinium reagent, (PQ/sup 2 +/)/sub surf./, can be photoreduced to (PQ/sup +/)/sub surf./ and this reduced species can be used to effect H/sub 2/ evolution if a Pt catalyst is incorporated into the polymer. Efficiency for conversion of monochromatic 632.8 nm light to H/sub 2/ exceeds 6%, compared to much less than 1% for the naked p-type Si without the surface catalyst system. Studies of n-type semiconductor (photoanode) electrode materials modified with biferrocene-based redox mediators for I/sup -/ ..-->.. I/sub 3//sup -/ oxidation have been undertaken for comparison to ferrocene-based reagents for the same reaction; a five- to ten-fold overall improvement in heterogeneous I/sup -/ ..-->.. I/sub 3//sup -/ rate can be achieved using the two-electron mediator compared to the one-electron transfer system.
- Research Organization:
- Massachusetts Inst. of Tech., Cambridge (USA)
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 6727863
- Report Number(s):
- DOE/ER/04178-4
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
140505* -- Solar Energy Conversion-- Photochemical
Photobiological
& Thermochemical Conversion-- (1980-)
AMINES
AMMONIUM COMPOUNDS
ANODES
AZINES
CATALYSIS
CATALYSTS
CATHODES
CHEMICAL REACTIONS
CHEMISTRY
COMPLEXES
DERIVATIZATION
DIENES
EFFICIENCY
ELECTROCATALYSTS
ELECTROCHEMICAL CELLS
ELECTRODES
ELECTRON TRANSFER
ELEMENTS
ENERGY GAP
ENERGY STORAGE
EQUIPMENT
FERROCENE
HALOGENS
HETEROCYCLIC COMPOUNDS
HYDROCARBONS
HYDROGEN
INDIUM COMPOUNDS
INDIUM PHOSPHIDES
IODINE
IRON COMPLEXES
MATERIALS
METALS
N-TYPE CONDUCTORS
NONMETALS
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
OXIDATION
P-TYPE CONDUCTORS
PH VALUE
PHOSPHIDES
PHOSPHORUS COMPOUNDS
PHOTOANODES
PHOTOCATHODES
PHOTOCHEMICAL ENERGY STORAGE
PHOTOCHEMISTRY
PHOTOELECTROCHEMICAL CELLS
PLATINUM
PLATINUM METALS
PNICTIDES
POLYENES
PYRIDINES
PYRIDINIUM COMPOUNDS
QUATERNARY COMPOUNDS
REDOX REACTIONS
REDUCTION
RESEARCH PROGRAMS
SEMICONDUCTOR MATERIALS
SEMIMETALS
SILICON
SOLAR EQUIPMENT
STORAGE
TRANSITION ELEMENT COMPLEXES
TRANSITION ELEMENTS
VOLTAMETRY