Hierarchical NiFe-Layered Double Hydroxide Coupled with Bimetallic NiFe-MOF Electrocatalysts for the Oxygen Evolution Reaction

Abstract

It is crucial to utilize extremely efficient and economical catalysts for the energy-intensive and kinetically slow oxygen evolution process. Here, we fabricated a NiFeLDH coupled with the NiFe-MOF catalyst with a unique hierarchical structure using a facile and rapid electrodeposition and electrochemical activation strategy. With a low overpotential of about 187 mV at 10 mA cm^–2, the NiFeLDH/NiFe-MOF/NF demonstrates exceptional stability for more than 1000 h. Additionally, the produced NiFeLDH/NiFe-MOF/NF could provide high current densities of 500 and 1000 mA cm^–2 in 6 M KOH at relatively low overpotentials of 293 and 353 mV, respectively. The construction of heterojunctions provides abundant interfacial active sites and optimizes catalytic activity by adjusting the surface electronic structure and energy levels. This serves to enhance the intrinsic activity of the catalyst. Density functional theory (DFT) calculations further prove that the construction of NiFeLDH regulates the band structure of metal sites, enhances the catalytic performance for the oxygen evolution reaction (OER), and lowers the intermediate medium’s adsorption free energy.