Localisation of electrochemical oxidation processes in nickel and cobalt hexacyanoferrates investigated by analysis of the multiplet patterns in X-ray photoelectron spectra

Nickel and cobalt hexacyanoferrate-modified gold electrodes were prepared b y electrochemical synthesis. These samples were investigated by X-ray photo electron spectroscopy (XPS) after removal of the modified electrodes from t he electrochemical cell at different potentials and transfer into the ultra high vacuum of the spectrometer. A careful analysis of the multiplet split ting of the 2p photoemission lines of the transition metal ions and compari son with suitable reference compounds and with calculations reveals that th e electrochemical oxidation occurs at the iron sites in K2Ni[Fe(CN)(6)] and at the cobalt sites in the related compound K2Co[Fe(CN)(6)].