Carbon dioxide conversion to hydrocarbons at silver electrode surfaces: Raman Spectroscpic evidence for surface carbon intermediates

Abstract

Intense Raman spectra from silver electrode surfaces at −0.2 V (SCE) in 0.1 M KF (and other electrolyte) solutions are interpreted in terms of graphitic carbon surface layers. Similar spectra have been recorded from dry silver surfaces polished in an atmosphere of air or CO 2. The source of carbon in the electrochemical studies appears to be atmospheric CO 2 which generates the electroactive species: aquated CO 2 (at pH 5.5) and CO 3 2−(at pH 11). It appears probable that CO 2 in its solution form is electroreduced to an unstable silver surface-formate complex which in turn spontaneously decomposes to carbon.