Seminars Archive

Electrochemical In situ Sum Frequency Generation Spectroscopy for Electrodeposition and Corrosion Applications

Abstract
This seminar will focus on in situ electrochemical Sum-Frequency Generation (SFG) and Difference-Frequency Generation (DFG) spectroscopies, applied to metal electrodeposition and corrosion. In particular, the understanding of the potential-dependent spectroelectrochemical behaviour of adsorbed CN¯ during metal plating and corrosion provides useful information for the rationalisation of technological processes. Results on the following systems will be presented. (i) Potential-dependent electrochemical behaviour of Au(111), (100), (110) and (210) electrodes in contact with neutral aqueous solutions of KCN. SFG and DFG spectra were analysed quantitatively with a model for the second order non linear susceptibility, accounting for vibrational and electronic effects; the contribution of both free and bound electrons has been considered. Details of adsorption energetics and kinetics were obtained. (ii) CN¯ adsorption on polycrystalline gold during potentiostatic electrodeposition from KAu(CN)2 and KAu(CN)4 solutions. Analysis of SFG spectra with a single-resonance model allowed to single out the electrokinetic effects of the two reduction processes in terms of vibrational properties of adsorbed CN¯. Parameters related to the electronic structure of the interface have been derived from the non-resonant part of the SFG spectra. (iii) The behaviour of polycrystalline Au, Au-Cu (Cu 25 %) and Au-Ag-Cu (Ag 10%, Cu 15%) electrodes in contact with neutral aqueous solutions of KCN was studied as a function of potential in the double-layer charging and anodic ranges. Information, relevant to the electroplating of Au-alloys and to the performance of soluble-anode systems, was derived in terms of the impact of adsorption on the electronic structure of the electrode, as a function of electrode alloy composition and applied potential.