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In this paper we report on the reactivity of adsorbed cyanide deriving from ligand release during metal electrodeposition from cyanocomplex solutions of Au(I), Au(III), Ag(I) and Cu(I) in H 2 O and D 2 O. When CN¯ is adsorbed at cathodic potentials in excess of the HER threshold, metal-dependent reactivity can be detected by SERS. Finite surface coverages with adsorbed CN¯ at such cathodic potentials can be obtained only if CN¯ is delivered directly to the cathode surface as by decomplexing of the cyanocomplexes of the metals undergoing cathodic reduction. In Au(I) and Au(III) baths, Au-CN¯ reacts with Au-H• and is hydrogenated to adsorbed CH 2 =NH and CH 3 -NH 2 .In Ag(I) baths, Ag-CN¯ reacts with Ag-H • giving rise to polycyanogens. No reactivity of Cu-CN¯ was found, under otherwise identical conditions. Our conclusions are supported also by dedicated DFT molecular computations.

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This paper reports an in situ Raman study of Cu electrodeposition from an acidic sulfate solution in the presence of bis-͑3-sulfopropyl͒-disulfide Na salt ͑SPS͒. In the absence of chloride, in situ surface-enhanced Raman spectra scarcely show few labile features in a narrow range of cathodic potential. When Cl − ions are added to the deposition bath, several features are clearly visible in the spectra, showing that SPS is adsorbed on the copper surface in a wide potential window during Cu electroplating.