Journal of Photochemistry and Photobiology A: Chemistry
Dawn of the evolution of photoelectrochemistry
Section snippets
Scope of photoelectrochemistry
A number of authors has provided definitions of photoelectrochmistry in their review papers. Kuwana [1] defined it as:
- (a)
Introduction of photo-excitation into the electrochemical system.
- (b)
Formation of the excited state through the electrochemical process.
In my early report [2], it was defined as:
- (a)
Reaction on the electrode in excited state:
- 1.
Excitation of the electrode (metal or semiconductor).
- 2.
Excitation of substances (adsorbed molecules, etc.) at the interface between the electrode and solution.
- 3.
- 1.
Becquerel effect
The French scientist Becquerel immersed two other metal electrodes such as platinum, gold, silver, brass, and silver coated with silver halogenide on the surface into acidic, neutral, and alkaline electrolytic solutions. Exposing one of the electrodes to sunlight, he found that electric current flows through the external circuit between two electrodes. The current was very small, with the pointer on the galvanometer only moving several degrees. Becquerel reported these results at Academy in
Appearance of TiO2
After the studies on Ge by Brattain and coworkers, every typical monocrystalline semiconductor that was easily available as a single crystal in the 1960s was investigated in photoelectrochemical research. The following shows such semiconductors in the chronological order in which they were studied.n-Ge 1955 n-Si 1958 n-CdS 1960 n-, p-GaAs 1965 n-ZnO 1966 p-NiO 1966 n-ZeSe 1967 n-, p-GaP 1968 n-SnO2 1968 n-KTaO3 1968
Semiconductor electrodes other than Ge and Si are oxide semiconductors, chalcogenide
Dye sensitization of photoelectrochemical process
Photoelectrochemical process always occurs after semiconductor electrodes absorb light with the wavelength of the intrinsic absorption band. Most semiconductors merely absorb part of the sunlight spectrum. In terms of effective use of sunlight, the working wavelength band of photoelectrode reaction should be expanded. In 1873, Vogel [10] already discovered dye sensitization by the use of silver halide photosensitive material. Since then, a massive amount of information on sensitizing dyes has
Concluding remarks
This report attempts to provide a historical outline of the progress of photoelectrochemistry. The information, however, may not be complete due to the limited knowledge of the author. In recent years, other than the use of solar energy, progress is centering around environmental improvement and the generation of hydrogen by the complete decomposition of water by semiconductor photocatalyst; many reports and literature on these themes are available.
References (28)
- et al.
Electrochim. Acta
(1961) - et al.
J. Electroanal. Chem.
(1967) - T. Kuwana, Electroanalytical Chemistry, vol. 1, Marcel Dekker Inc., New York, 1966, p....
J. Chem. Soc. Jpn. Ind. Chem. Sec.
(1969)Compt. Rend.
(1839)- et al.
Seisankenkyu
(1966) J. Chem. Phys.
(1940)- et al.
Bell System Tech. J.
(1955) - et al.
J. Chem. Soc. Jpn. Ind. Chem. Sec.
(1969) - et al.
Nature
(1972)