Promoting Electrocatalytic CO 2 Reduction to CH 4 by Copper Porphyrin with Donor-Acceptor Structures.

Molecular catalysts have been receiving increasingly attention in the electrochemical CO reduction reaction (CO RR) with attractive features such as precise catalytic sites and tunable ligands. However, the insufficient activity and low selectivity of deep reduction products restrain the utilization of molecular catalysts in CO RR. Herein, a donor-acceptor modified Cu porphyrin (CuTAPP) is developed, in which amino groups are linked to donate electrons toward the central CuN site to enhance the CO RR activity. The CuTAPP catalyst exhibited an excellent CO -to-CH electroreduction performance, including a high CH partial current density of 290.5 mA cm and a corresponding Faradaic efficiency of 54.8% at -1.63 V versus reversible hydrogen electrode in flow cells. Density functional theory calculations indicated that CuTAPP presented a much lower energy gap in the pathway of producing *CHO than Cu porphyrin without amino group modification. This work suggests a useful strategy of introducing designed donor-acceptor structures into molecular catalysts for enhancing electrochemical CO conversion toward deep reduction products.