Modeling Exsolution of Pt from ATiO<sub>3</sub> Perovskites (A = Ca/Sr/Ba) Using First-Principles Methods
Abhinav S. Raman, Aleksandra Vojvodić
Abstract
Exsolution of transition metals from host perovskites has emerged as a unique synthesis method for designing catalysts for energy applications. Here, using accurate first-principles density functional theory, coupled with an ab initio steered molecular dynamics and umbrella sampling framework, we rationalize both the energetics as well as the dynamics of the exsolution process of a quintessential system: Pt-doped ATiO3 (A = Ca/Sr/Ba) perovskites and identify the major driving forces for Pt exsolution. From the developed ab initio thermodynamic framework, we find that Pt exsolution from ATiO3 (A = Ca/Sr/Ba) perovskites has a distinct host-perovskite facet dependence and likely proceeds through sub-surface vacancy formation followed by diffusion of the doped Pt to the surface of the host perovskite. The molecular dynamics simulations reveal that the exsolution process has a clear temperature and host-perovskite dependence, establishing that only specific dopant-host perovskite combinations at favorable thermophysical conditions result in the catalyst with the novel properties. This opens new paths for the predictive synthesis of intelligent catalysts.