MECHANISTIC STUDIES OF CO2 REDUCTION ON A MEDIATED ELECTRODE WITH CONDUCTING POLYMER AND INORGANIC CONDUCTOR FILMS

Electrocatalytic reduction of CO2 on a metal complex-immobilized polya niline (PAn)/Prussian blue (PB)-laminated electrode has been investiga ted by means of long-term electrolysis, liquid chromatography/mass spe ctroscopy (LC/MS) and in situ Fourier transform infrared (FTIR) reflec tion absorption spectroscopy. The major products were lactic, acetic, and formic acids, methanol, and ethanol. The roles of PAn and the meta l complex 8-dihydroxynaphthalene-3,6-disulfonatoferrate(II)] are to re nder CO2 chemically active by combining the electrophilic carbon atom with the amino group of PAn and the basic oxygen atom with the central metal of the complex, and that of PB is to provide catalytically H-ad s atoms on its zeolitic lattice. The activated CO2 is hydrogenated and converted to organic acids and alcohols by the reaction with H-ads at oms. It is suggested that formaldehyde is a precursor for the organic acids (except formic acid) and alcohols and the insertion reactions of CO2 into intermediates are essential to the formation of C-2 and C-3 compounds.