Distal Synergistic Effect in Bimetal–Organic Framework for Superior Catalytic Water Oxidation

Metal–organic frameworks (MOFs) are emerging as promising electro-catalysts for the oxygen evolution reaction (OER). The bimetallic design strategy was further adopted in MOFs to elevate the OER performance by a synergistic effect. The proximal metal–oxygen–metal bonding configuration with typical 3 d π –2 p π –3 d π interaction was apparently essential for an effective electronic coupling between the metal centers. Here, we report an example of distal synergy in a bimetal–organic framework exhibiting a better OER activity than the monometallic counterparts, as well as the conventional proximal synergy. To achieve a current density of 10 mA·cm –2, our electrodeposited bimetallic MOF, Co–Ni(TCNQ) 2 (H 2 O) 2 (TCNQ = 7,7,8,8-tetracyanoquinodimethane), on a glassy-carbon electrode required an overpotential value of 220 mV. X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations revealed distinctive electronic coupling between the Co(II)-3 d 7 and Ni(II)-3 d 8 centers, despite being 9 Å apart, leading to an overall charge delocalization in the structure via TCNQ.