Carbon Dioxide Adsorption on Monoclinic Zirconia: DFT Calculations Support the Role of Polycoordinated Carbonates in IR Spectroscopy

Abstract Developing the conversion of CO 2 in heterogeneous catalysis requires accurate characterization of the species reacting on the surface of metal oxide catalysts or supports. In this field, zirconia is used for its ability to adsorb and activate CO 2 . Nevertheless, the first and crucial step of this process, the CO 2 adsorption over ZrO 2 surfaces, is not fully understood experimentally. In particular, the diversity of surface carbonate species makes the IR analysis very complicated. This work presents a computational study on the adsorption of CO 2 on all the sites of the four most stable monoclinic ZrO 2 surfaces, (001), (011), (111), and (−111). With this exhaustive sampling of real particle surfaces, our main purpose is to characterize the surface carbonates in terms of structures, adsorption energies and nature of surface ions, coupled with a vibrational study and a Bader atomic charge analysis. Our results show that the polycoordinated carbonates are key species in the CO 2 adsorption over monoclinic ZrO 2 . The CO 2 adsorption energies largely depend on the coordination numbers of the involved Zr 4+ cations. This study offers a revisited IR assignment of the carbonate adsorbed on zirconia, showing the specificity of metal oxides with highly charged metal cations.