Reaction of CO2 with UO3 Nanoclusters

Adsorption of CO 2 o uranium oxide, (UO 3 ) n , clusters was modeled using density functional theory (DFT) and coupled cluster theory (CCSD(T)). Geometries and reaction energies were predicted for carbonate formation (chemisorption) and Lewis acid-base addition of CO 2 (physisorption) to these (UO 3 ) n clusters. Chemisorption of multiple CO 2 moieties was also modeled for dimer and trimer clusters. Physisorption and chemisorption were both predicted to be thermodynamically allowed for (UO 3 ) n clusters, with chemisorption being more thermodynamically favorable than physisorption. The most energetically favored (UO 3 ) 3 (CO 2 ) m clusters contain tridentate carbonates, which is consistent with solid-state and solution structures for uranyl carbonates. The calculations show that CO 2 exposure is likely to convert (UO 3 ) n o uranyl carbonates.