Linker Defects in Metal–Organic Frameworks for the Construction of Interfacial Dual Metal Sites with High Oxygen Evolution Activity

Designing efficient electrocatalysts based on metal–organic framework (MOF) nanosheet arrays (MOFNAs) with controlled active heterointerface for the oxygen evolution reaction (OER) is greatly desired yet challenging. Herein, a facile strategy for the synthesis of MOF‐based nanosheet arrays (γ‐FeOOH/Ni‐MOFNA) is developed with abundant heterointerfaces between Ni‐MOF and γ‐FeOOH nanosheets by introducing linker defects to the former. The experimental and theoretical results show the key role of linker defects in inducing the growth of secondary γ‐FeOOH nanosheets onto the surface of Ni‐MOFNAs, which further leads to the formation of interfacial Ni/Fe dual sites with high oxygen evolution activity. Notably, the resulting γ‐FeOOH/Ni‐MOFNA exhibits excellent OER performance with low overpotentials of 193 and 222 mV at 10 and 100 mA cm−2, respectively. Furthermore, the study of the structure–performance relationship of MOF‐based heterostructures reveals that Ni sites at the interface of the γ‐FeOOH/Ni‐MOFNA have higher activity than those at the interface of NiFe layered double hydroxide and Ni‐MOFNA. This study provides a new prospect on heterostructured electrocatalysts with highly active sites for enhanced OER.