Single-Atom Iridium Catalysts on Covalent Frameworks: Structural Tuning for Superior Oxygen Evolution

The rational design of active and stable electrodes is crucial for the development of efficient and durable water electrolyzers. However, theoretical studies exploring the structural factors that dictate catalytic activity and dissolution stability remain scarce. This study investigates several factors by examining the trends in activity, stability, and the oxidation state of Ir single atoms during the oxygen evolution reaction (OER). Using computational methods such as Density Functional Theory (DFT) and Molecular Dynamics (MD) simulations, the structure of Ir single-atom catalysts (SACs) is analyzed across a range of oxidation states, which is influenced by electrode potential and environmental pH. The findings indicate that applying potential to Ir SAC-supported covalent organic framework (COF) in the range of 0.5 ∼ < U ∼ < 1.1 can lead to the formation of an OIrOH structure, resulting in outstanding OER activity. Importantly, while applying the electrode potential is not necessary to overcome the potential-limiting step, it is crucial for the formation and stabilization of the highly active Ir SAC structure. This work offers valuable insights to guide experimental efforts in designing high-performance Ir SACs with enhanced OER activity.