An Electrochemical and Spectroelectrochemical Study of the Electrodeposition of Au from KAU(CN)2 Solutions containing 4-Cyanopyridine and Cetylpyridinium Chloride

Abstract

SUMMARYIn this paper we report an electrochemical and in-situ FT-IRRAS study of the cathodic md anodic behaviour of Au in neutral KAu(CN)2 solutions in the presence of organic substances which are of interest as hydrogen scavengers and cathodic depolarisers for Au and Au-alloy electrodeposition baths not containing free cyanide: 4-cyanopyridine and cetylpyridinium chloride. The electrochemical behaviour is studied by cyclic voltammetry, differential capacitance and electrochemical impedance spectroscopy. Some relationships between the nature of the organic additives and the electrodic behaviour of Au(CN)2− during the electrodeposition of Au are highlighted. Details of the surface species forming under cathodic and anodic polarisation in the presence of the additives are given. The formation of different kinds of Au-CN− films at the electrode has been recognised and the effects of the additives on their stability has been assessed.