Photoelectrochemistry of Oxidation Layers: A Novel Approach to Analyze Photocurrent Energy Spectra

Abstract

In the course of the last 30 years, photoelectrochemical techniques have been shown to be useful tools to characterize oxidation layers. Analyzing photocurrent versus applied potential plots, or, more often, photocurrent versus photon energy spectra, has actually allowed to identify the presence in the oxidation layers of one or several semiconducting components. However, up to now, when applied to photocurrent energy spectra of complex oxide scales, the usual analysis of these spectra provided only more or less qualitative information on the nature (through bandgap energies) and, in favourable cases, on the semiconducting type, of the oxides present in the scale. The novel approach discussed here to the description of the photocurrent resulting from several contributions under modulated light conditions, allowed for robust fitting of experimental photocurrent energy spectra, and to extract from the latter more quantitative information.