Publication 774

Proc. Natl. Acad. Sci. U.S.A, 112 (22), 4911-4924, 2015 DOI:10.1073/pnas.1507063112
Efficient and selective molecular catalyst for the CO2-to-CO electrochemical conversion in water

Université Paris Diderot, Sorbonne Paris Cité, Laboratoire d’Electrochimie Moléculaire, Unité Mixte de Recherche Université - CNRS N° 7591, Bâtiment Lavoisier, 15 rue Jean de Baïf, 75205 Paris Cedex 13, France

Substitution of the four paraphenyl hydrogens of iron tetraphenylporphyrin by trimethylammonio groups provides a water-soluble molecule able to catalyze the electrochemical conversion of carbon dioxide into carbon monoxide. The reaction, performed in pH-neutral water, forms quasi-exclusively carbon monoxide with very little production of hydrogen, despite partial equilibration of CO₂ with carbonic acid—a low pK_a acid. This selective molecular catalyst is endowed with a good stability and a high turnover frequency. On this basis, prescribed composition of CO–H₂ mixtures can be obtained by adjusting the pH of the solution, optionally adding an electroinactive buffer. The development of these strategies will be greatly facilitated by the fact that one operates in water. The same applies for the association of the cathode compartment with a proton-producing anode by means of a suitable separator