COPPER DISSOLUTION IN BROMIDE MEDIUM IN THE ABSENCE AND PRESENCE OF HEXAMETHYLENETETRAMINE (HMTA)

The anodic electrochemical behavior of copper in bromide medium, in th e absence and presence of hexamethylenetetramine (HMTA), has been stud ied, using electrochemical and spectroelectrochemical techniques. The copper dissolution in the absence of HMTA was dependent on mass transp ort of bromide ions. A porous CuBr film was formed at positive overpot entials. The film growth mechanism followed the nucleation, growth and superposition (NGS) model, with instantaneous nucleation and a diffus ion controlled growth of a three dimensional film. In the presence of the inhibitor, a passivant Cu/HMTA/Br- film was observed. This film ha s slow growth kinetics, favored by mass transport. The inhibitory effe ct was observed for the potential range between 0 mV and + 800 mV (SCE ). A maximum inhibitory efficiency, near 100%, was observed for 15 mM HMTA. The nature of the passivant film was confirmed by in situ surfac e-enhanced Raman scattering (SERS) and SEM/EDX measurements. (C) 1998 Elsevier Science Ltd. All rights reserved.