Molecular catalysis of the electrochemical and photochemical reduction of CO2 with Fe and Co metal based complexes. Recent advances

Reduction of CO2 is a fruitful approach for storage of renewable electric energy as well as for the production of value added chemicals. Using variously substituted iron tetraphenylporphyrins and iron and cobalt macrocyclic pentadendate N5 complexes electrochemically or photochemically reduced to their active states, selective and efficient molecular catalysis of the CO2-to-CO and of the CO2-to-HCOOH conversion was achieved at low overpotential. From fruitful joint experimental and mechanistic studies rooted in the analysis of cyclic voltammograms, the mechanisms for catalysis were fully deciphered, allowing not only to give a complete picture of the catalytic processes but also to identify the main parameters for optimizing the catalyst structure. Efficient CO2 catalysis was performed not only in aprotic but also in aqueous conditions, opening the way to the design of electrochemical or photo-electrochemical cells, a key step for future applied devices.