Accurately Modulating Binuclear Metal Nodes of Metal-Organic Frameworks for Oxygen Evolution.

The accurate manipulation of the species and locations of catalytic centers is crucial for regulating the catalytic activity of catalysts, which is essential for their efficient design and development. Metal-organic frameworks (MOFs) with coordinated metal sites are ideal materials for investigating the origin of catalytic activity. In this study, we present a Ni-MOF featuring novel Ni-based binuclear nodes with open metal sites (OMSs) and saturated metal sites (SMSs). The nickel was replaced by iron to obtain NiFe-MOF. In the electrocatalytic oxygen evolution reaction, NiFe-MOF exhibited an overpotential and Tafel slope of 370 mV@10 mA cm and 87.06 mV dec, respectively, which were higher than those of Ni-MOF (283 mV@10 mA cm and 39.59 mV dec, respectively), demonstrating the superior performance of NiFe-MOF. Furthermore, theoretical calculations revealed that iron as an SMS may effectively regulate the electronic structure of the nickel catalytic center to reduce the free energy barrier Δ of the rate-determining step.