(599d) Novel Approaches to Efficient Pourbaix Stability Analysis of Multicomponent Systems

Designing stable catalysts remains a challenge for several electrochemical reactions, often resulting in a trade-off between activity and stability. A prominent example is the oxygen evolution reaction (OER), which typically requires highly oxidizing potentials and corrosive environments. The search for active yet stable electrocatalysts has also led to increasingly complex systems, including mixed metal oxides [1]. In light of these advances in catalyst design, efficient theoretical stability predictions for multicomponent electrochemical systems are essential.

Pourbaix analysis is a useful approach to predict the thermodynamic stability of materials under varying electrochemical potentials and pH conditions. However, constructing Pourbaix diagrams for systems containing more than three non-OH elements often requires significant computational resources. Herein, we have implemented a pre-processing algorithm within the pymatgen code that constructs a compositional convex hull to identify relevant species for Pourbaix analysis. This algorithm reduces the computational cost of Pourbaix diagram construction by several orders of magnitude, which significantly expands the breadth of multicomponent systems that can be described [2]. To demonstrate the utility of this method, we apply the Pourbaix analysis to density functional theory (DFT)-predicted energetics of promising bimetallic Ru-based pyrochlore (A₂Ru₂O₇) catalysts for OER.

In addition to improving Pourbaix diagram construction efficiency, this pre-processing algorithm paves the way for automating stability screening for many multicomponent systems. To pursue this goal, we have developed a simple yet descriptive screening metric that can be applied to stability screening frameworks. Efficient Pourbaix diagram construction and stability screening introduces various opportunities to predict new stable species and modify existing materials to extend their regions of Pourbaix stability.

References:

[1] Song, F., et al. (2018). Journal of the American Chemical Society, 140(25), 7748-7759.

[2] Patel, A. M., et al. (2019). Physical Chemistry Chemical Physics, 21(45), 25323-25327.