Spectro-electrochemical study of the influence of ligand adsorption on the reaction rate of the electrodeposition of silver complexes

Chronoamperometry and surface enhanced Raman spectroscopy (SERS) in combination with electrochemical impedance spectroscopy (EIS) were used to investigate the steady state reduction of silver thiosulphate, silver thiocyanate and silver 1,8-dihydroxy-3,6-dithiaoctane (DTO) complexes, together with the adsorption phenomena in those systems. The electrochemical parameters were obtained from a numerical computational method, solving the basic mass transport equations in accordance to the proposed generalised model for the reduction of the three complexes. The influence of the bulk ligand concentration on the kinetic parameters was explained by the occurrence of adsorbed species. The adsorption of AgS2O3-, AgSCN and AgDTO+ was evidenced and quantified through the determination of their surface coverage as a function of the electrode potential.