A benzimidazole-linked bimetallic phthalocyanine–porphyrin covalent organic framework synergistically promotes CO2 electroreduction

Abstract

Bimetallic catalysts have recently emerged as promising candidates for CO₂ reduction. However, it is still critical to strategically synthesize atomically precise bimetallic catalysts and clarify the interaction mechanism of bimetal sites. Herein, we connected the active metallic porphyrin and phthalocyanine moieties by the unique benzimidazole linkage to obtain a novel Ni,Co-based bimetallic covalent organic framework (denoted as NiPc-CoPor-imi-COF), for efficient electrocatalytic CO₂ conversion. Compared with its monometallic Ni and Co counterparts, NiPc-CoPor-imi-COF with a synergistic effect exhibited much higher activity and selectivity with a maximum CO faradaic efficiency (FE_CO) of 97.1%. Mechanistic studies revealed that the efficient charge transport along the COF backbone promoted electronic communication between the bimetallic active sites and enabled regulation of the intrinsic activity of each catalytic center, namely improving the activity of Ni sites by promoting *COOH generation and optimizing the selectivity of Co sites by depressing *H formation, thus ultimately achieving high CO₂ conversion efficiency. This work provides insights into synergistic catalysis with bimetallic sites for efficient CO₂ reduction.