Enhancing electrochemical CO2 reduction with monoamino-functionalized cobalt tetraphenylporphyrin catalysts

• Monoaminated Co-TPP aids CO 2 adsorption and activation, raising CO current density. • Amino group in Co-TPP enhances stability, >90 % FE CO over 24 h CO 2 ER. • Monoamino Co-TPP is better for CO 2 ER and soluble for processing. Metal porphyrins have gathered significant attention in electrochemical reduction of CO 2 due to their well-defined active sites and stable macrocyclic framework. However, their catalytic efficiency, and stability still require further improvement. Building upon this foundation, further optimization of the catalyst is both feasible and necessary. In this work, a cobalt porphyrin functionalized with a single amino group (Co-TPPNH 2 ) was prepared, which was highly dispersed in conductive carbon Ketjen Black (KCB) using a simple impregnation method. The resulting amino-functionalized cobalt porphyrin/KCB composite (Co-TPPNH 2 /KCB) achieved a CO Faradaic efficiency of 95 % ( η = 586 mV), comparable to that of the unmodified cobalt porphyrin sample, owing to the preserved CoN 4 active site. Notably, the CO current density over Co-TPPNH 2 /KCB was higher than that over its unmodified counterpart across the potential range of −1.2 V to −0.7 V ( vs. RHE), reaching a maximum of 42.6 mA/cm 2 –17 mA/cm 2 higher than the unmodified sample. Furthermore, the incorporation of an amino group significantly enhances the catalyst’s electrochemical stability. Density Functional Theory (DFT) calculations demonstrated that the amino group could facilitate CO 2 adsorption and activation. Crystal Orbital Hamilton Population (COHP) analysis confirmed that the amino group strengthened the overall chemical bonding within the cobalt-porphyrin molecule, thereby increasing molecule’s resistance to electrochemical degradation and suppressing structural decomposition during catalysis.