Synergistic electroreduction of carbon dioxide to carbon monoxide on bimetallic layered conjugated metal-organic frameworks

Abstract

Highly effective electrocatalysts promoting CO₂ reduction reaction (CO₂RR) is extremely desirable to produce value-added chemicals/fuels while addressing current environmental challenges. Herein, we develop a layer-stacked, bimetallic two-dimensional conjugated metal-organic framework (2D c-MOF) with copper-phthalocyanine as ligand (CuN₄) and zinc-bis(dihydroxy) complex (ZnO₄) as linkage (PcCu-O₈-Zn). The PcCu-O₈-Zn exhibits high CO selectivity of 88%, turnover frequency of 0.39 s^-1 and long-term durability (>10 h), surpassing thus by far reported MOF-based electrocatalysts. The molar H₂/CO ratio (1:7 to 4:1) can be tuned by varying metal centers and applied potential, making 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; ZnO₄ complexes act as CO₂RR catalytic sites while CuN₄ centers promote the protonation of adsorbed CO₂ during CO₂RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO₂RR toward syngas synthesis.