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

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 (angstrom) and evaluating the differences of charge density and charge transfer (Delta CT). 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 Delta CT 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.