Bimetallic 2D Metal Organic Frameworks for High Selective Ethylene Glycol Electrooxidation

Upcycling polyethylene terephthalate (PET) into metal-organic framework (MOFs)-based electrocatalyst for ethylene glycol oxidation reaction (EGOR) represents a promising pathway to achieving plastic pollution remediation and overall sustainable chemicals utilization. However, electrocatalytic performance is limited by an insufficient understanding of the origins of intrinsic activities. Herein, an ultrathin PET-derived bimetallic 2D MOFs (2D-CoNi-PET) is synthesized to elucidate the decisive factors governing the EGOR activity and selectivity. Mechanistic investigations demonstrate that Ni incorporation induces the generation of high-valence Co species, enhancing the deprotonation capability and consequently reducing the onset potential for EGOR. The concomitant decrease in electron density at Co centers also strengthens the bonding with adsorbed oxygen species, improving adsorption kinetics of related reactants and facilitating the spontaneous reaction rate for high EGOR activity at elevated applied potentials. Moreover, comparative studies reveal that the reaction pathways from EG to formic acid (FA) differs between 2D and 3D MOFs due to their distinct adsorption capability for reactants/intermediates. Thus-obtained 2D-CoNi-PET nanosheets achieve a low potential of 1.41 V (vs RHE), high Faradaic efficiency, and favorable selectivity (91%) of FA at 100 mA cm^-2, far beyond that of 3D-CoNi-BDC (42%), demonstrating the advantageous of geometry design and the successive adsorption-reaction chain of the electrocatalysts.