Reaction of CO₂ with UO₃ Nanoclusters

Area of Science:

• Computational Chemistry
• Materials Science
• Nuclear Chemistry

Background:

• Uranium oxides are key materials in nuclear fuel cycles.
• Understanding their interaction with gases like carbon dioxide is crucial for safety and waste management.
• The surface chemistry of uranium oxide clusters is not fully characterized.

Purpose of the Study:

• To model the adsorption of carbon dioxide (CO2) onto uranium oxide (UO3) clusters.
• To investigate the thermodynamics and mechanisms of CO2 binding, including physisorption and chemisorption.
• To predict the favored structures of CO2-adsorbed uranium oxide clusters.

Main Methods:

• Density Functional Theory (DFT) calculations were employed to model adsorption.
• Coupled Cluster Theory (CCSD(T)) was used for high-accuracy energy predictions.
• Geometries and reaction energies for physisorption and chemisorption were computed.

Main Results:

• Both physisorption and chemisorption of CO2 onto (UO3)n clusters are thermodynamically favorable.
• Chemisorption, leading to carbonate formation, is more energetically favorable than physisorption.
• The most stable structures involve tridentate carbonates, consistent with known uranyl carbonate structures.

Conclusions:

• CO2 exposure is predicted to convert uranium oxide clusters into uranyl carbonates.
• The findings provide insights into the reactivity of uranium oxides with atmospheric CO2.
• This study advances the understanding of surface interactions relevant to nuclear materials.