Photoelectrochemical evolution of elemental fluorine at TiO/sub 2/ electrodes in anhydrous hydrogen fluoride solutions
Although elemental fluorine has been known for more than 100 years, it is still produced by Moissan's original method, electrolysis of anhydrous HF/alkali fluoride solutions. Only one convenient alternative route for preparing fluorine has been reported to date. Several oxide and oxyfluoride semiconductors have valence band edges that are positive of the F/sup -/, F/sub 2/ standard potential, and holes photogenerated in the valence band of these materials should, in principle, be capable of oxidizing F/sup -/ to F/sub 2/. In aqueous fluoride-containing solutions other processes such as water oxidation and photoanodic corrosion compete effectively with F/sup -/ oxidation, and no fluorine is formed. Even in nonaqueous solutions these wide bandgap semiconductors photocorrode, unless sufficient reductant is present to compete for photogenerated holes. In anhydrous solutions containing sufficient quantities of fluoride ion is reasonable to expect that fluorine might be generated photoelectrochemically at a semiconductor surface which is somehow stabilized against photocorrosion. They report here that elemental fluorine is evolved at n-type TiO/sub 2/ electrodes in anhydrous HF/NaF solutions. Using bandgap illumination (365 nm) gaseous F/sub 2/ is produced with a sizable photovoltage and high power conversion and current efficiencies. While electrode photocorrosion occurs to some extent in all these experiments, it may be minimized greatly by using fluorine-doped TiO/sub 2/ electrodes.
- Research Organization:
- Univ. of Texas, Austin, (USA)
- OSTI ID:
- 6974447
- Journal Information:
- J. Am. Chem. Soc.; (United States), Vol. 110:11
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
14 SOLAR ENERGY
FLUORINE
PRODUCTION
HYDROFLUORIC ACID
PHOTOCHEMICAL REACTIONS
TITANIUM OXIDES
CATALYTIC EFFECTS
ELECTROCHEMISTRY
EXPERIMENTAL DATA
PHOTOCHEMISTRY
CHALCOGENIDES
CHEMICAL REACTIONS
CHEMISTRY
DATA
ELEMENTS
HALOGENS
HYDROGEN COMPOUNDS
INFORMATION
INORGANIC ACIDS
NONMETALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
TITANIUM COMPOUNDS
TRANSITION ELEMENT COMPOUNDS
400500* - Photochemistry
140505 - Solar Energy Conversion- Photochemical
Photobiological
& Thermochemical Conversion- (1980-)
400400 - Electrochemistry