Zirconium oxide has gained interest as both a catalyst support and a catalyst of its own, mostly owing to its weak acid and basic sites and stability under oxidizing and reducing atmosphere. As a catalyst ZrO2 is interesting material for biomass-related reaction networks which typically involve carbon oxides and display rich chemistry with different surfaces sites1. In particular, the surface hydroxyl groups are important for the reactivity of carbon oxides and they can be manipulated experimentally e.g. by thermal treatment2. Using density functional theory calculations we have examined the stability of the most abundant zirconia surfaces under the reactive environment. Upon systematic increase of the amount of incorporated water, we predict structural motifs that water forms on the zirconia surfaces. We observe that the largest stabilization of the zirconia surfaces is achieved when 50- 75 % of the adsorbed water is dissociated. Moreover, we account systematically for the oxygen vacancies which are likely preset on zirconia and may contribute to the arrangement of the adsorbed water molecules. While the oxygen vacancies distort the zirconia surfaces, incorporation of water plays in an important role in regaining the stability of the surfaces. Finally, the adsorption of CO and CO2 and the formation of formate, carbonate and bicarbonate species on different surface models and hydroxyl-group concentrations are discussed. Calculations unravel that e.g., on ZrO2 (-111) CO prefers to adsorb as a formate but formate formation is a complex process with relative high activation energy. Carbon dioxide preferably forms a carbonate species and favors low coordinates sites for which it competes with OH species. 1 S. Kouva, K. Honkala, L. Lefferts and J. Kanervo Catal. Sci. & Tech.5, 3473 (2015) 2 S. Kouva, J. Andersin K. Honkala, J. Lehtonen, L. Lefferts and J. Kanervo PCCP 16, 20650 (2014)

Adsorption of water and carbon oxides on monoclinic zirconia from first principles calculations

251st National Meeting (2016)

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