In-situ SERS experiments during the electrodeposition of gold in the presence of benzyldimethylphenylammonium chloride

Hydrogen incorporation is one of the main problems encountered in electroforming and electroplating processes and can result in serious material embrittlement. Use of organic additives has been shown to reduce hydrogen incorporation efficiently in electrodeposition of gold from neutral cyano–aurate baths. We report the results of: (i) in-situ surface enhanced Raman spectroscopy experiments; supported by (ii) electrochemical measurements (cyclic voltammetry, differential capacitance); and (iii) GC–MS analyses, relevant to electrodeposition of gold from a KAu(CN)2 aqueous solution, containing benzyldimethylphenylammonium chloride (BDMPAC). The cathodic coadsorption of cyanide and the quaternary ammonium salt causes a remarkable depolarisation of the metal deposition. The results obtained match well with the hypothesis of two surface reactions, taking place at potentials more negative than −1300 mV versus Ag ∣ AgCl, which involve the additive and bring about the consumption of both hydrogen and cyanide adsorbed on the electrode. Depolarising effects and reduced hydrogen incorporation accomplished with the use of BDMPAC can thus be related to its hydrogen and cyanide scavenging action.