A SERS Investigation of Cyanide Adsorption and Reactivity during the Electrodeposition of Gold, Silver and Copper from Aqueous Cyanocomplexes Solutions

摘要

In this paper we report on the reactivity of adsorbed cyanide deriving fromligand release during metal electrodeposition from cyanocomplex solutions ofAu(I), Au(III), Ag(I) and Cu(I) in H2O and D2O. When CN is adsorbed at cathodicpotentials in excess of the HER threshold, metal-dependent reactivity can bedetected by SERS. Finite surface coverages with adsorbed CN at such cathodicpotentials can be obtained only if CN is delivered directly to the cathodesurface as by decomplexing of the cyanocomplexes of the metals undergoingcathodic reduction. In Au(I) and Au(III) baths, Au-CN reacts with Au-H and ishydrogenated to adsorbed CH2=NH and CH3-NH2. In Ag(I) baths, Ag-CN reacts withAg-H giving rise to polycyanogens. No reactivity of Cu-CN was found, underotherwise identical conditions. Our conclusions are supported also by dedicatedDFT molecular computations.