Efficient and selective molecular catalyst for the CO 2 -to-CO electrochemical conversion in water

Abstract

Significance: CO 2 -to-CO electrochemical conversion is a key step in the production of liquid fuels through dihydrogen-reductive Fischer–Tropsch chemistry. Among molecular catalysts, iron porphyrins reduced electrochemically to the Fe(0) state are particularly efficient and led to a deeper understanding of mechanisms involving coupled bond-breaking proton–electron transfer processes. The replacement of nonaqueous solvents by water should make the CO 2 -to-CO half-cell reaction much more attractive for applications, particularly because it would allow association with a water-oxidation anode through a proton-exchange membrane. Here it is demonstrated that electrochemical CO production catalyzed by a water-soluble iron porphyrin can occur with high catalytic efficiency. Manipulation of pH and buffering then allows conversions from those involving complete CO selectivity to ones with prescribed CO–H 2 mixtures.