The Effect of Illumination on the Anodic Dissolution of Cadmium Sulphide in the Presence of a Redox System

An electrochemical cell — Indium|CdS monocrystal|Electrolyte|Pt was used to study the transfer of electrons and ions through the interface CdS/electrolyte using the current‐voltage relationship in the dark and under illumination with 480 nm light. During illumination with light of wavelength less than 510 nm electron‐hole pairs will be generated. The electrons from the sulphide ion and/or electrolyte ions adsorbed on CdS, can recombine with the holes and the remaining electrons from this recombination enter the conduction band as free charge carriers. The presence of quinhydrone prevents the neutralization of sulphide ions in the surface and the anodic dissolution of CdS under illumination is reduced.