Electrocatalytic CO 2 Reduction at Lower Overpotentials Using Iron(III) Tetra( meso -thienyl)porphyrins

The optical and electrochemical properties, as well as the CO2 reduction capability, of two different iron(III) thienyl-porphyrins, namely, iron(III) tetra(meso-thien-2-yl)porphyrin (FeTThP) and iron(III) tetra(meso-5-methylthien-2-yl)porphyrin (FeTThMeP), are directly compared to those of iron(III) tetra(meso-phenyl)porphyrin (FeTPP). Through exploitation of mesomeric stabilization effects, FeTThP and FeTThMeP were able to catalytically reduce CO2 to CO with comparable Faradaic efficiencies and TONCO relative to FeTPP, all while using an overpotential 150 mV lower than the benchmark catalyst.