J. Photochem. Photobiof. A: Chem., 60 (1991) 129-130 129

Book Review

Solar Energy Conversion: A Photoelectrochemical Approach by Yuri V. Pleskov, published by Springer, Berlin, 1990,163 pp., price DM 178.00, hardback, ISBN 3-540-51474-o.

Yuri Pleskov is a senior member of the A. N. Frumkin Institute of Electrochemistry in Moscow, an electrochemist of great distinction and an authority on semiconductor electrochemistry, on which he has published extensively. His comprehensive and scholarly approach has appeared to excellent advantage in his specialist review articles and his 1986 book Semiconductor Photoelectrochemktq, co-authored with Yu. Ya. Gurevich. It is a little disappointing, although perhaps not surprising, that the concise treatment he essays in Solar Energy Conversion does not come so readily to him. Nor has he been well served by a translator and editor who have created or failed to temper many stilted English constructions, and have misused - for example - displace for display, dopes for dopants and the ubiquitous effect for affect.

This 150 page specialist monograph on the photoelectrochemical conversion of solar energy is the first by a single author. Its brevity and consistency come as a considerable relief in a field littered with less digestible multi-author multi-volume reports. However, too much of the theoretical treatment appears as though it has been cut down to size from larger works, and the description of state-of-the-art devices bears tell-tale signs of Pleskov’s involuntary isolation from the photoelectrochemical communities of the U.S. and Western Europe.

The book converges rapidly on its theme of semiconductor-based systems for the conversion of solar energy to electrical or chemical energy from a brief and quaint appraisal of the role of solar energy in national economies; Pleskov quotes GNP figures, showing Japan alongside Poland at just $500 per capita, that owe more to ancient history than to economics.

The following chapters set the scene by covering, a little patchily, the basics of semiconductor physics and photoelectrochemistry. Thermodynamic and quasi- thermodynamic aspects of semiconductor electrochemistry - the structure of the double’layer, the relative domains of band-edge pinning and Fermi level pinning and electrode stability - are well handled, although too much space is devoted to settling an old score with Reiss and Heller concerning the measurement of the Fermi level of the hydrogen electrode. However, the kinetic treatment of carrier generation, transport and recombination is rather perfunctory and the important concept of carrier collection efficiency is barely mentioned.

Successive chapters deal with cells for the production of hydrogen by the photoelectrolysis of water and other inorganic substances such as hydrogen sulphide, semiconductor suspensions and colloids, and regenerative cells for the production of electricity. The approach is rightly illustrative rather than exhaustive and these chapters contain some excellent cameos and are generally readable. However, Pleskov’s policy of passing lightly over book work has led him to submerge some important ideas and definitions as obiter dicta and footnotes where a more methodological approach would have been clearer, particularly in the treatment of conversion efficiencies. The later chapters are more successful: the difference in behaviour between macroscopic and

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microscopic electrodes is well drawn, and the complexities of heterostructure and combination electrodes neatly sketched.

There are some surprising omissions; the Texas Instruments Solar Energy Storage System is well covered but the most efficient photoelectrochemical storage cell yet devised, that of Stuart Licht and coworkers, is not mentioned. Discussion of the photodetoxification of aqueous effluent streams by the combination of heat and light in high-irradiance light, a subject of considerable commercial interest, is absent. Quantum effects in small particles and superlayer lattices appear too briefly. There is an unhelpful digression on optimization of solar cell-water electrolyser combinations, and the

unpromising process of photointercalation is dealt with at some length. A brief concluding chapter on protective coatings for semiconductor electrodes

makes interesting reading, although it seems an odd place in which to introduce some basic current-potential equations.

The book is aimed at students and researchers working in the fields of photoelectrochemistry and photocatalysis. Both will find it an informative and readable contribution, but somehow I doubt that an intelligent newcomer to the field, having read only this book, will have formed a wholly clear picture of why semiconductor photoelectrochemistry works, why bands bend and unbend and why light-driven processes occur at a thermodynamic underpotential. He may need to have recourse to other works in which the basic principles are more formally set out and the performance of the various types of device more critically compared.

Mary Archer Newnham College

Cambridge CL32 9ND, U.K.