Reprogramming the Microenvironment of Cobalt Phthalocyanine by a Targeted Multifunctional π-Conjugated Modulator Enables Concerted CO2 Electroreduction

Architecting the interfacial microenvironment is highly desirable for achieving enhanced electrochemical CO2 reduction reaction (CO2RR), but it is still a challenge. Herein, a π-conjugated matrix of graphitic carbon nitride/graphene (C3N4/G) is built to tailor cobalt phthalocyanine (CoPc) into an efficient CO2 electrocatalyst. The enhanced mechanism of microenvironment-mediated CO2RR on CoPc/C3N4/G is fully distinguished by integrating the experimental and theoretical results. C3N4/G is energetic for CO2 enrichment and H2O dissociation to produce activated H* species, which enables a ceaseless yet fast power injection into the kinetic process of the CO2RR. Meanwhile, the electron structure of Co active sites modulated by C3N4/G also thermodynamically favors the conversion of CO2 and intermediates. Consequently, in a flow cell, CoPc/C3N4/G delivers a high turnover frequency value (50.5 s–1), gratifying CO selectivity (∼100%) as well as current density (67.8 mA cm–2) at −1.1 V vs RHE, and maintains a Faradaic efficiency for CO above 98% in an ultrawide potential window of over 500 mV, ranking among the state-of-the-art macrocyclic complex-based catalysts currently reported for CO2 reduction to CO. This work underlines the significance of well-tailored microenvironment design in the electrocatalytic system.