Doubly Urea‐Bridged Face‐to‐Face Dinuclear Metalloporphyrins for Efficient Electrocatalytic CO₂ Reduction in Aqueous Solutions

Electrocatalytic CO2 reduction reaction (CO2RR) is involved in new energy conversion scheme. Although many electrocatalysts for CO2RR have been developed, improving the activity and selectivity of molecular catalysts in aqueous solutions remains a challenge. Herein, the synthesis and electrocatalytic CO2RR features of doubly urea-bridged face-to-face dinuclear metalloporphyrins 1-M (M = Co, Fe) are reported. By bridging two porphyrin units through two urea groups, 1-Co and 1-Fe with two porphyrin units arranged in a face-to-face manner are synthesized. Both complexes are active and selective for electrocatalytic CO2-to-CO conversion in CO2-saturated bicarbonate solutions, achieving >96.3% FECO for 1-Co and >93.8% FECO for 1-Fe. Importantly, 1-M is more active than mononuclear analogues 2-M and 3-M for electrocatalytic CO2RR. The partial current for the CO production with 1-M is four times larger than that with 2-M and five times larger than that with 3-M. The CO2RR overpotential with 1-M is smaller than that with 2-M and 3-M by more than 180 mV. These results suggest the collaboration between the two metalloporphyrin units for electrocatalytic CO2RR. This work therefore is significant to present 1-M as active and selective CO2RR electrocatalysts and to showcase the collaboration between two metalloporphyrin units in boosting CO2RR catalysis.