(569w) Theoretical Insights for Designing Stable Low-Iridium Oxygen Evolution Catalysts

The global push towards decarbonization has greatly incentivized the advancement of hydrogen production technologies. Coupled with renewable energy, proton exchange membrane (PEM) water electrolyzers are emerging as a promising technology on the path to green hydrogen, offering a minimal footprint. Yet, scaling the Oxygen Evolution Reaction (OER) with stable, cost-effective anodes remains a significant challenge. Iridium oxide (IrO₂), despite its catalytic prowess, is limited by scarcity, and promising alternative catalysts like Ruthenium Oxide (RuO₂) often fall short of the operational lifetimes required for industrial scalability. As might be expected, doping Ir into RuO₂ can enhance its durability, but the specifics regarding the origin of this enhancement and the extent to which iridium loading can be minimized remain unclear. Our research leveraged Density Functional Theory (DFT) and Monte Carlo (MC) simulations to investigate iridium's role in enhancing the stability of RuO₂. DFT was employed to design stability rules for Ru in coordination with Ir and to derive energetics for an MC algorithm that simulated the Ir dopant distribution, accounting for thermal fluctuations under nanoparticle synthesis conditions. Importantly, we found that the oxophilicity of iridium and the material morphology have significant implications for the amount of iridium needed to stabilize the RuO₂ lattice. This led to the development of a high-performance low-Ir RuO₂-based material that demonstrated remarkable endurance under commercially-relevant conditions. The synthesized catalyst maintained its stability for several thousand hours at a current density of 2 A/cm² in a PEM electrolyzer, offering a viable pathway towards sustainable and scalable green hydrogen production and highlighting potential design rules for doped low-iridium oxygen evolution materials.