CO Oxidation to CO₂ on Uranium Dioxide Molecules through Intermediate O₂U(η¹-CO)

Investigations on the reactions of uranium oxide molecules with CO offer new inspiration for the design of promising high-efficiency catalysts for CO activation using actinide materials. Herein, we contribute a combined matrix-isolation infrared spectroscopic and theoretical study of CO oxidation to CO₂ on uranium dioxide (UO₂) molecules in solid argon. The reaction intermediate O₂U(η¹-CO) is generated spontaneously at the bands of 1893.0, 870.6, and 801.3 cm^-1 during codeposition and annealing. Upon the following irradiation, CO₂ is substantially produced by the consumption of O₂U(η¹-CO), indicating the catalytic conversion of CO to CO₂ through the intermediate O₂U(η¹-CO). In C¹⁸O isotopic substitution experiments, the yields of ¹⁶OC¹⁸O convincingly confirm that one of the oxygen atoms in CO₂ derives from UO₂. The reaction pathways are discussed based on the theoretical and experimental results.