Enlarging the π‐Conjugation of Cobalt Porphyrin for Highly Active and Selective CO2Electroreduction

Abstract Heterogeneous molecular catalysts have attracted considerable attention as carbon dioxide reduction reaction (CO 2 RR) electrocatalysts. The π‐electron system of conjugated ligands in molecular catalysts may play an important role in determining the activity. In this work, by enlarging π‐conjugation through appending more aromatic substituents on the porphyrin ligand, altered π‐electron system endows the as‐prepared 5,10,15,20‐tetrakis(4‐(pyren‐1‐yl)phenyl)porphyrin Co II with high Faradaic efficiency (ca. 95 %) for CO production, as well as high turnover frequency (2.1 s −1 at −0.6 V vs. RHE). Density functional theory calculation further suggests that the improved electrocatalytic performance mainly originates from the higher proportion of Co orbital and the CO 2 π* orbital in the HOMO of the (Co−porphyrin−CO 2 ) − intermediate with larger π‐conjugation, which facilitates the CO 2 activation. This work provides strong evidence that π‐conjugation perturbation is effective in boosting the CO 2 RR.