2025 AIChE Annual Meeting

Predicting Stability of Doped RuO2 for Water Electrolysis

Efficient water electrolysis is crucial for mitigating climate change. Water electrolysis, a carbon neutral process, could replace carbon-emitting processes for industrial hydrogen production. Additionally, green hydrogen can be used to easily store and transport energy generated from intermittent, renewable sources. State of the art catalysts typically have high overpotentials for the oxygen evolution reaction step of water electrolysis. Very active catalysts, like RuO2, are unstable, and there is often a tradeoff between activity and stability. Both activity and stability need to be well understood to design better catalysts for water electrolysis. This work attempts to understand the stability of OER catalysts by analyzing what dopant properties are important for stabilizing RuO2.

Cation vacancy formation energy is used as a metric for stability, as this is a well established mechanism for catalyst degradation in the literature. DFT at the PBE+U level of theory is used to calculate the energy of RuO2 with different surface terminations, dopants, and dopant placements. Dopant placement and surface termination are determined under realistic synthesis and experimental conditions, respectively. Vacancy formation energy is subsequently calculated with the appropriate dopant placement and surface termination.

Under both synthesis and experimental conditions, all Ru atoms in the CUS site were terminated with oxygens. It was energetically more favorable to terminate more oxophilic dopants. Less oxophilic dopants were more stabilizing to nearby Ru atoms, although long range stabilization was not observed. These results indicate that dopant oxophilicity is a good predictor of RuO2 stabilization; however, further computational and experimental research is needed to validate this conclusion.