An in situ spectroelectrochemical investigation into the electrodeposition of CU from acidic sulphate solutions in the presence of poly(ethylene glycol)

This research deals with the effects of PEG during Cu electrodeposition from an acidic sulphate solution. This investigation was carried out with electrochemical (cyclic voltammetry with a rotating-disk electrode, potentiostatic and galvanostatic electrodeposition), and spectroelectrochemical (in situ Surface Enhanced Raman Spectroscopy) techniques. Potentiostatically grown layers were examined by scanning electron microscopy. Adsorption of PEG on the growing Cu surface can be inferred from electrokinetic, SERS and morphological evidence, gathered with PEG-free and PEG-containing solutions: variations of the estimated exchange current density, qualitative and quantitative differences in the potentiostatic transients, effects on the three-dimensional crystallisation mode under both compact and dendritic growth conditions, appearance of surface-enhanced PEG-related Raman bands. Surface spectra also revealed cathodic reactivity of adsorbed PEG. Spectral features can be interpreted as relating to a vinyl ether group deriving from polymer fragmentation with ether bond cleavage, followed by an elimination reaction.