DFT Study of 17O NMR Spectroscopy Applied to Zirconia Surfaces and Nanoparticles

Solid state 17O NMR is emerging as a new tool to characterize the nature of active sites on the surface of oxide materials. In particular, the identification and quantification of low-coordinated sites can provide useful information to assess the chemical properties and the chemical reactivity of oxide nanostructures. In this modeling study, we have considered regular and stepped surfaces of tetragonal ZrO2 as well as zirconia nanoparticles, either stoichiometric or oxygen-deficient. To this end, we have performed density functional theory calculations and determined the 17O chemical shift and the quadrupolar coupling constants of the various surface sites. The results show that the 17O chemical shift can clearly distinguish the O2C, O3C, and O4C sites on the surface, steps, or bulk regions of zirconia. Since oxide surfaces exposed to atmospheric ambient conditions react with water and carbon dioxide, we have also considered the adsorption properties of the t-ZrO2 (101) surface toward these molecular species, and the corresponding 17O and 13C chemical shifts.