Time-dependent in situ SERS study of CN− adsorbed on gold

In this paper, we report an in situ SERS study of CN− adsorbed on gold from a KAu(CN)2 bath during the application of a sequence of galvanostatic square waves. The understanding of the time-dependent spectroelectrochemical behaviour can provide useful information for the rationalisation of technological processes, such as pulse plating. Both electrode potential and SERS spectra have been recorded during the application of the square wave current program. A quantitative analysis of the potential transients, corresponding to the current square waves and of the SERS spectra, has been carried out. The peak position, the full width at half maximum (FWHM) and the peak area have been estimated for each spectrum and the dynamic Stark tuning has been evaluated. Quantitative analysis of our data results in a dynamic description of the mechanisms of adsorption and electroreduction prevailing in different cathodic overvoltage ranges.