Impact of Applied Potential on the Facet Ratio and Size of Ir and Cu Catalysts

The surface energy of a catalyst material is important for understanding the fundamental behavior of nanoparticles and bulk crystals, particularly in terms of activity, selectivity, durability, and stability. Computational studies of electrocatalysts provide valuable insight into the stability of electrode surfaces under realistic environments, including solid/liquid interfaces. In this work, we model the electrode/solid surface using the density functional theory (DFT), and electrolyte/liquid using the implicit solvation model. Importantly, we examined the surface energies of low-index facets of Ir and Cu crystals in an aqueous electrolyte as a function of applied electrode potential. The results show that each surface facet of the neutral surface belongs to an initial potential which is called the potential of zero charge (PZC). Both Ir and Cu (111) facets have higher PZC values relative to other studied facets. Ir and Cu (111) facets exhibit the most stable surfaces with low surface energy profiles within the range of applied potential, while (110) facets show the lowest stability for electrocatalyst applications. This study shows that the surface energies are highly sensitive to the applied potential and leads to the change in particle size and facet ratio under the applied potentials.