Three-Dimensional Phthalocyanine Metal-Catecholates for High Electrochemical Carbon Dioxide Reduction

The synthesis of a new anionic 3D metal-catecholate framework, termed MOF-1992, is achieved by linking tetratopic cobalt phthalocyanin-2,3,9,10,16,17,23,24-octaol linkers with Fe₃(-C₂O₂-)₆(OH₂)₂ trimers into an extended framework of roc topology. MOF-1992 exhibits sterically accessible Co active sites together with charge transfer properties. Cathodes based on MOF-1992 and carbon black (CB) display a high coverage of electroactive sites (270 nmol cm^-2) and a high current density (-16.5 mA cm^-2; overpotential, -0.52 V) for the CO₂ to CO reduction reaction in water (faradaic efficiency, 80%). Over the 6 h experiment, MOF-1992/CB cathodes reach turnover numbers of 5800 with turnover frequencies of 0.20 s^-1 per active site.