Proceedings of the 1986 International Congress on Renewable Energy Sources. Kinetic study of the photocorrosion of n-type semiconductor electrodes. International Congress on Renewable Energy Sources [18-23 Mayo 1986, Madrid].

Consejo Superior de Investigaciones Científicas.
Benito, R.M. Nozik, A.J.

1987

CIENA
1113
v. 2

84-00-6674-X

A kinitic model describing the effects of light intensity on the photodecomposition of n-type semiconductor electrodes is developed. Various mechanisms have been deribed assuming that the semiconductor decomposition and the oxidation of the reducing agent reactions are both multistep. We have considered that every step of the decomposition reaction is carried out by reaction with a hole, while the oxidation reaction of the reducing agent can take place in two different ways. A) by reaction with a hole in every step, or B) by reaction with a hole in the first step, and in the rest by reaction with the intermediate formed in the first step. For both mechanisms three limit cases been studied, which correspondto reversible or irreversible first steps of the competing oxidation reactions. An expression for the stabilization fraction as a function of the light intensity has been derived in every case for the two mechanisms. It was found that the photostability of the semiconductor could either increase, decrease or been independent with increased light, depending on the kinetic characteristics of each case. Our results indicate that when the desired redox reaction of the reducing agent in the electrolyte was multistep, with the first step being reversible the photostability of the semiconductor electrode increases with light intensity. The effect on the photostability of other variables, such as the number of steps of the involved reactions, and the concentration of the reducing agent, has also been studied. ABSTRACT. INTRODUCTION. KINETIC STUDY. RESULTS AND DISCUSSIONS. REFERENCES.

Presenta diagrs. y gráfs.

GENERAL; ENERGIA SOLAR; CONVERSION DE LA ENERGIA; FOTOQUIMICA; CELDAS FOTOELECTROQUIMICAS; SEMICONDUCTORES; EXPERIMENTOS;