Amino acids adsorption onto the (111) surface of cubic zirconia: a density functional theory study

Abstract

The adsorption of six amino acids onto (111) surface of cubic ZrO2 was theoretically investigated using density functional theory (DFT). DFT calculations with D3 dispersion correction were carried out with the PBE exchange–correlation functional. Mechanism, molecular adsorption structures, and energies were calculated. The (111) surface of cubic ZrO2 was modeled using a slab with 9 atomic layers (81 atoms). The slab thickness was 7.3 A, and a vacuum separation of 12 A was used with periodic boundary conditions. The results showed that the order of the molecular adsorption energies is ASP > HYP > GLY > ALA > LYS > PRO. Furthermore, adsorption of amino acids on the zirconia surface showed complete hydrogen transfer from GLY, ALA, HYP, and ASP to the surface. For LYS and PRO, hydrogen transfer does not occur. Topological analysis of the electron localization function (ELF) was applied to study the nature of the molecule-surface interactions. It was found that the dissociation of molecules and strong chemical bonds of adsorbed atoms to surface oxygen atoms play an important role in the adsorption mechanism.