Correlation between CdS photoanodic behaviour and electrode chemical modifications: An X‐ray photoelectron spectroscopic study

The photosensitivity increase of CdS films as a function of the illumination time, is correlated to chemical changes of the electrode surface, analysed by XPS. It is shown that the formation of Cd(OH) 2 or CdO is responsible for the photosensitivity change of the illuminated electrode in contact with H 2 O/NaOH alone. When thiocresol or p ‐mercaptobenzoic acid is added as reductant, a layer of organic compounds is formed on the electrode during the photoelectrochemical process. However, the XPS and photocurrent spectra indicate that this layer does not prevent the occurrence of Cd(OH) 2 or CdO responsible for the photosensitivity changes of the CdS film.