Engineering Bimetal Synergistic Electrocatalysts Based on Metal–Organic Frameworks for Efficient Oxygen Evolution

Benefiting from metal–organic frameworks (MOFs) unique structural characteristics, their versatility in composition and structure has been well explored in electrochemical oxygen evolution reaction (OER) processes. Here, a ligand/ionic exchange phenomenon of MOFs is reported in alkaline solution due to their poor stability, and the active species and reaction mechanism of MOFs are revealed in the OER process. A series of mixed Ni‐MOFs and Fe‐MOFs are synthesized by straightforward sonication and then directly used as catalyst candidates for OER in alkaline electrolyte. It can be confirmed via ex situ transmission electron microscopic images and X‐ray diffraction patterns analysis, that the bimetallic hydroxide (NiFe‐LDH) is generated in 1.0 m KOH in situ and acts as protagonist for oxygen evolution. The optimized catalyst (FN‐2) exhibits a lower overpotential (275 mV at a current density of 10 mA cm−2) and excellent long‐term stability (strong current density for 100 h without fading). The revelation of the real active species of MOF materials may contribute to better understanding of the reaction mechanism. A bimetal synergistic electrocatalyst (FN‐2) based on Fe‐MOFs@Ni‐MOFs is successfully synthesized via a simple method. The as‐prepared FN‐2 exhibits superior catalytic activity and stability in the oxygen evolution reaction. A ligand/ionic‐exchange phenomenon of Fe‐MOFs@Ni‐MOFs in alkaline solution is found and it is confirmed that the active species (NiFe‐LDH) is produced in alkali conditions.