Electroreduction of carbon dioxide

The mechanism and kinetics of electroreduction of carbon dioxide in aqueous solutions on metals with high and moderate hydrogen overvoltages (Sn, Ie, Bi, Sb, Cd, Zn, Cu, Pb, Ga, Ag, Au, Ni, Fe, W, Mo, and glassy carbon) are studied. The class of metals on which CO2 electroreduction takes place is shown to be rather wide. The effects of different factors on partial currents of electroreduction are investigated. Those factors are: potential, stirring, CO2 partial pressure, pH of the solution, the type and concentration of buffer solutions, and electrode material. The influence of various conditions on the transformation of CO2− anion-radicals intermediately generated during CO2 electroreduction is studied. The optimal electrodes for electroreduction are those with moderate hydrogen overvoltages, i.e. those which exhibit CO2 electroreduction near the zero-charge potential in the range of maximum CO2 adsorption.