Synergistic Electroreduction of Carbon Dioxide to Carbon Monoxide on Bimetallic Layered Conjugated Metal-Organic Frameworks

The development of highly selective and active electrocatalysts promoting the CO2 reduction reaction (CO2RR) is highly desirable to address current environmental challenges and to produce value-added chemicals and carbon-based fuels. 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, named as PcCu-O8-Zn. The PcCu-O8-Zn exhibits high CO selectivity of 88%, a TOF of 1408 h1 and long-term durability (> 10 h), which surpasses thus by far the reported MOF-based electrocatalysts. The molar H2/CO ratio can be tuned by varying the metal centers and the applied potential rendering the 2D c-MOFs highly relevant for syngas industry applications. The contrast experiments combined with operando surface-enhanced IR-absorption spectroelectrochemistry and theoretical calculation unveil a synergistic catalytic mechanism; the ZnO4 complexes act as catalytic sites for the CO2 conversion while the CuN4 centers promote the protonation of adsorbed CO2 during the CO2RR. This work offers a strategy on developing bimetallic MOF electrocatalysts for synergistically catalyzing CO2RR toward syngas synthesis.