ELECTROCATALYTIC REDUCTION OF CO2 AND O-2 WITH ELECTROPOLYMERIZED FILMS OF VINYL-TERPYRIDINE COMPLEXES OF FE, NI AND CO

We have prepared and characterized, by cyclic voltammetry in acetonitrile and DMF (under N-2 or CO2) for CO2 reduction, and in aqueous media for O-2 reduction, iron, nickel and cobalt complexes of a terpyridine (tpy) and vinyl-terpyridine (v-tpy). These materials exhibit electrocatalytic activity towards the reduction of CO2 and the magnitude of the catalytic effect is a function of the metal center. In the case of electropolymerizable metal complexes (those incorporating v-tpy) electrodeposited films exhibited higher electrocatalytic activity than the corresponding tpy complexes in solution. In the case of electropolymerized films of [Fe(v-tpy)(2)](2+), electrocatalysis for CO2 reduction was observed at potentials below -1.0 V which represents a very significant diminution (of about 1 V) in the overpotential. In the case of oxygen, the electrocatalytic activity of the electropolymerized films as well as the predominant product (peroxide or water) was dependent on the surface coverage.