Studies on the n‐GaAs Photoanode in Aqueous Electrolytes. 1. Behaviour of the Photocurrent in the Presence of a Stabilizing Agent

The competition, at the n‐GaAs/Fe2+ photoanode, between the anodic decomposition of the semiconductor, the anodic oxidation of Fe2+ ions and surface recombination was studied as a function of the light intensity, the electrode potential, and the Fe2+ concentration by means of the rotating‐ring‐disc electrode technique. The results are interpreted on the basis of a reaction scheme, in which the competing processes are linked through the intermediates of the decomposition reaction. Numerical calculations, based upon this reaction scheme, of the relationship between the stabilization ratio and the photocurrent density, between the stabilization ratio and the electrode potential, and between the photocurrent density and the electrode potential are in good agreement with the experimental data.