Uncoordinated amino groups of MIL-101 anchoring cobalt porphyrins for highly selective CO₂ electroreduction

Electrocatalytic carbon dioxide reduction reaction (CO₂RR) presents a sustainable route to address energy crisis and environmental issues, where the rational design of catalysts remains crucial. Metal-organic frameworks (MOFs) with high CO₂ capture capacities have immense potential as CO₂RR electrocatalysts but suffer from poor activity. Herein we report a redox-active cobalt protoporphyrin grafted MIL-101(Cr)-NH₂ for CO₂ electroreduction. Material characterizations reveal that porphyrin molecules are covalently attached to uncoordinated amino groups of the parent MOF without compromising its well-defined porous structure. Furthermore, in situ spectroscopic techniques suggest inherited CO₂ concentrate ability and more abundant adsorbed carbonate species on the modified MOF. As a result, a maximum CO Faradaic efficiency (FE_CO) up to 97.1% and a turnover frequency of 0.63 s^-1 are achieved, together with FE_CO above 90% within a wide potential window of 300 mV. This work sheds new light on the coupling of MOFs with molecular catalysts to enhance catalytic performances.