In Situ FT-IR Spectroscopic Study of CO(2) and CO Adsorption on Y(2)O(3), ZrO(2), and Yttria-Stabilized ZrO(2)

[Image: see text] In situ FT-IR spectroscopy was exploited to study the adsorption of CO(2) and CO on commercially available yttria-stabilized ZrO(2) (8 mol % Y, YSZ-8), Y(2)O(3), and ZrO(2). All three oxides were pretreated at high temperatures (1173 K) in air, which leads to effective dehydroxylation of pure ZrO(2). Both Y(2)O(3) and YSZ-8 show a much higher reactivity toward CO and CO(2) adsorption than ZrO(2) because of more facile rehydroxylation of Y-containing phases. Several different carbonate species have been observed following CO(2) adsorption on Y(2)O(3) and YSZ-8, which are much more strongly bound on the former, due to formation of higher-coordinated polydentate carbonate species upon annealing. As the crucial factor governing the formation of carbonates, the presence of reactive (basic) surface hydroxyl groups on Y-centers was identified. Therefore, chemisorption of CO(2) most likely includes insertion of the CO(2) molecule into a reactive surface hydroxyl group and the subsequent formation of a bicarbonate species. Formate formation following CO adsorption has been observed on all three oxides but is less pronounced on ZrO(2) due to effective dehydroxylation of the surface during high-temperature treatment. The latter generally causes suppression of the surface reactivity of ZrO(2) samples regarding reactions involving CO or CO(2) as reaction intermediates.