(696a) Predicting Metal Dynamics, Surface, and Segregation Energies in High Entropy Alloys for Sintering and Catalyst Durability

In the realm of heterogeneous catalysis, the stability, and shapes of active metal catalyst sites during reactions are critical for catalytic activity. This study aims to enhance our understanding of catalytic systems by building on previous coordination-based approaches [1] that predicted general configurational energies of metal nanostructures. However, the generalized scheme does not explicitly define partial coordination to neighboring atoms, making it challenging to understand the stability of adatoms during non-equilibrium states of diffusion or migration. Therefore, we use density functional theory (DFT) to calculate activation energies for atomic diffusions/migrations over various FCC surfaces to evaluate the stability of metal atoms. From these results, we extract coordination-based parameters to fit to the energies of atoms at non-equilibrium distances. This extended model is used to gain a better understanding of surface restructuring and sintering in heterogeneous catalytic contexts, such as copper catalysts during electrochemical carbon dioxide reduction.

Moreover, the optimization of catalytic activity and selectivity in heterogeneous catalysis relies on various surface properties, particularly surface energies, and the distribution of site morphologies. Therefore, we also evaluate surface energies and predict the relative stabilities of various catalytic surfaces using the mentioned coordination schemes. We use periodic slabs and various metal nanoparticle (MNP) shapes to determine surface energies and extended this approach to multimetallic surfaces (alloys) to describe segregation behaviors in multimetallic alloys (MMAs) to predict the relative surface concentrations of the various constituent metals.

Overall, this physics-based approach allows for the effective screening of thermodynamic stabilities of alloy MNPs by integrating coordination schemes with structural and site information. The resulting models can be applied to calculate the energetics of any nanoparticle morphology and chemical composition, thus significantly accelerating the design of durable nanoalloys, potentially extending to high entropy alloys.

1. Roling, L.T., The Journal of Physical Chemistry C, 2017. 121(41): p. 23002-23010.