Potential-dependent reactivity of adsorbed cyanide during the electrodeposition of silver from cyanocomplexes: a study based onin-situsurface-enhanced Raman spectroscopy

Abstract

This paper reports on the reactivity of cyanide ligands released from Ag(I) cyanocomplexes during electrodeposition at very negative potentials. The study is based on in-situ surface-enhanced Raman spectroscopy (SERS) measurements performed during Ag electrodeposition from H 2 O and D 2 O based-electrolytes in order to pinpoint isotopic shifts. The investigation is complemented by electrochemical measurements -electrochemical impedance spectrometry (EIS) and cyclic voltammetry (CV) -as well as by SEM micrography. Surface-enhanced Raman spectroscopy spectroscopy disclosed details of the cathodic reactivity of adsorbed cyanide yielding amine that are typical of very negative polarisations and had not been observed in previous studies. The formation of cathodic films resulting from cyanide reactivity and giving rise to cathodic passivation and the cathodic reactivation corresponding to the increase in H . formation rate at the most negative investigated potentials have also been followed by potential-dependent EIS. The dependence of Ag electrodeposit morphology on cathodic potential correlates straightforwardly with the secondary inhibition scenario identified by SERS, CV and EIS.