Influence of LiTaO3 (0001) and KTaO3 (001) Perovskites Structures on the Molecular Adsorption of Styrene and Styrene oxide: A Theoretical Insight by Periodic DFT Calculations

Abstract

In this research, the adsorption of styrene and styrene oxide, both biomass derivatives, on KTaO₃ (001) and LiTaO₃ (0001) perovskite-like structures was studied from a theoretical point of view. The study was carried out using density functional theory (DFT) calculations. The adsorption phenomenon was deeply studied by calculating the adsorption energies (E_ads ), adsorbate-surface distances (Å) and evaluating the differences of charge density and charge transfer (ΔCT). For complexes adsorbed on KTaO₃ (TaO₂ , KO and K(OH)₂ exposed layers), the highest E_ads was found for styrene oxide, attributed to the oxygen reactivity of the epoxy group describing a strong interaction with the surface. However, when evaluating a K(O)₂ model, a more favorable interaction of styrene with the surface is observed, resulting in a high E_ads of -9.9 eV and a ΔCT of 3.1e. For LiTaO₃ , more favorable interactions are found for both adsorbates compared to KTaO₃ , evidenced by the higher adsorption energies and charge density differences, particularly for the styrene complex adsorbed on TaO₂ exposed layer (E_ads : -10.2 eV). For the LiO termination, the surface exposed oxygens are fundamental for the adsorption of styrene and styrene oxide, leading to a considerable structural distortion. The obtained results thus provide understanding of the structural features, surface reactivity and adsorption sites of LiTaO₃ and KTaO₃ perovskite in the context of a heterogeneous catalytic process, such as the oxidation of styrene.

Keywords: adsorption; density functional calculations; styrene; styrene oxide; tantalates.