ROLE OF OVERLAYER FORMATION IN THE CADMIUM CHALCOGENIDE/Fe (CN)//6**4** minus **/**3** minus PHOTOELECTROCHEMICAL CELL.

Irradiation of n-CdX (X equals S,Se) photoelectrodes in an electrolyte containing Fe (CN)//6**4** minus **/**3** minus causes formation of a left bracket Cd**I**I Fe**I**I**/**I**I**I(CN)//6 right bracket **2** minus **/**1** minus surface layer on the electrode which is detectable by diffuse reflectance FTIR analysis. This layer is shown to play an integral role in the inter-facial charge transfer process, and is responsible for the previously reported partial stabilization of n-CdS by a ferrocyanide electrolyte.