Synergistic Catalytic Sites in High‐Entropy Metal Hydroxide Organic Framework for Oxygen Evolution Reaction

The integration of multiple elements in a high‐entropy state is crucial in the design of high‐performance, durable electrocatalysts. High‐entropy metal hydroxide organic frameworks (HE‐MHOFs) are synthesized under mild solvothermal conditions. This novel crystalline metal–organic framework (MOF) features a random, homogeneous distribution of cations within high‐entropy hydroxide layers. HE‐MHOF exhibits excellent electrocatalytic performance for the oxygen evolution reaction (OER), reaching a current density of 100 mA cm−2 at ≈1.64 VRHE, and demonstrates remarkable durability, maintaining a current density of 10 mA cm−2 for over 100 h. Notably, HE‐MHOF outperforms precious metal‐based electrocatalysts despite containing only ≈60% OER active metals. Ab initio calculations and operando X‐ray absorption spectroscopy (XAS) demonstrate that the high‐entropy catalyst contains active sites that facilitate a multifaceted OER mechanism. This study highlights the benefits of high‐entropy MOFs in developing noble metal‐free electrocatalysts, reducing reliance on precious metals, lowering metal loading (especially for Ni, Co, and Mn), and ultimately reducing costs for sustainable water electrolysis technologies. A high‐entropy metal hydroxide organic framework (HE‐MHOF) is synthesized, combining five transition metals in a single‐phase crystalline structure. The material exhibits superior electrocatalytic performance for the oxygen evolution reaction, rivaling precious metal‐based catalysts. Operando X‐ray absorption spectroscopy and ab initio calculations reveal synergistic catalytic sites and the underlying reaction mechanism, demonstrating the potential of high‐entropy materials for sustainable energy technologies.