Operando Elucidation on the Working State of Immobilized Fluorinated Iron Porphyrin for Selective Aqueous Electroreduction of CO₂ to CO

Iron porphyrin-based molecular catalysts can electrocatalyze CO2 reduction to CO at nearly 100% selectivity in water. Nevertheless, the associated active sites and reaction mechanisms remain debatable, impeding establishment of design guidelines for effective catalysts. This study reports coupling operando experiments theoretical calculations immobilized 5,10,15,20-tetrakis(pentafluorophenyl) porphyrin Fe(III) chloride (FeF20TPP) electrocatalytic an aqueous phase. In UV–vis X-ray absorption near-edge structure spectra indicated persisting presence Fe(II) species during cathodic reaction, acting as catalytic that accommodate Fe(II)–CO adducts. Consistently, density functional pointed out ligand-reduced state with oxidized Fe, namely, [Fe(II)F20(TPP•)]−, prevails cycle prior rate-controlling step. work provides conclusive representation related working states Fe-based under conditions.