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

Electrocatalytic carbon dioxide reduction reaction (CORR) 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 CO capture capacities have immense potential as CORR electrocatalysts but suffer from poor activity. Herein we report a redox-active cobalt protoporphyrin grafted MIL-101(Cr)-NH for CO 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 CO concentrate ability and more abundant adsorbed carbonate species on the modified MOF. As a result, a maximum CO Faradaic efficiency (FE) up to 97.1% and a turnover frequency of 0.63 s are achieved, together with FE 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.