Rational modulating electronegativity of substituents in amorphous metal-organic frameworks for water oxidation catalysis

Oxygen evolution reaction (OER) is a limiting factor for water splitting due to multi-step transfer of four electrons and sluggish reaction kinetics. At present, metal-organic frameworks (MOFs) as OER catalyst still has some shortcomings, such as poor conductivity and high-temperature synthesis, which seriously limits its application in electrocatalysis. Here, we synthesize amorphous metal-organic frameworks (aMOFs) by a simple chemical method at room temperature. The X-ray photoelectron spectroscopy (XPS) results indicated that the different electronegativity of substituents could dramatically influence the metal center in aMOFs. These aMOFs exhibit different OER performances in basic aqueous solutions, in which the A0.25B–NiFe showed the lowest overpotential of 237 mV at 10 mA cm−2 current density and Tafel slope of 60 mV dec−1. These heuristic results demonstrate that the electronegativity of substituents has a profound influence on the metal active sites of the catalysts. This will provide a new strategy for accelerating the application of MOFs in electrocatalysis and energy conversion.