Catalysts for Green Hydrogen

The efficiency of electrocatalytic water splitting is critically limited by the stability of oxygen evolution reaction (OER) catalysts. Iridium oxide (IrO₂) remains the state-of-the-art OER catalyst, but its performance strongly depends on nanoparticle morphology and surface termination, both of which evolve dynamically under acidic oxidizing conditions.

 

In this work, we used ab initio thermodynamic modeling to investigate the morphological stability of IrO₂ nanoparticles, while in situ experimental observations from our collaborators provided real-time insight into the structural evolution under reaction conditions. By incorporating often-overlooked high Miller index (HMI) facets and realistic surface terminations into our Wulff constructions, we predicted potential-dependent nanoparticles consistent with experimental data.

 

Notably, our simulations reveal previously unreported morphological transformations, including facet-specific dissolution pathways that drive evolution toward HMI-dominated nanoparticles. We also show that both defect formation energies and kinetics are highly facet dependent. These results underline the interplay between thermodynamic and kinetic processes at the catalytic interface.

 

This theory–experiment approach highlights the importance of modeling potential-dependent surface dynamics and defect energetics when designing next-generation OER catalysts. By advancing a more complete understanding of how morphology evolves under electrochemical conditions, this study lays the groundwork for predictive catalyst design for scalable green hydrogen technologies.