A Density Functional Theory Study of CO Catalytic Conversion on Defected Actinide Dioxide AnO₂ Surface

Actinide dioxides AnO₂ are the most common forms of nuclear fuels in commercial nuclear reactors. Understanding the surface chemistry of AnO₂ is crucial to the operational safety, efficiency, recycling, and storage of nuclear fuels. Studies have shown that actinide materials could serve as highly efficient catalysts for the activation of H₂, CH₄, NH₃, etc., mainly due to actinide valent 5<i>f</i> electrons characterized by strong electron correlations and various oxides states. However, experimental studies of actinide systems are limited by their elevated safety requirement associated with radioactivity. In this simulation study, we employed first principles atomistic calculations based on density functional theory (DFT) to reveal the catalytic behavior of AnO₂ surface with O vacancies. We observe that O vacancies significantly change the electronic structure of AnO₂ surfaces, and act as the active sites of small molecules adsorption. We will show an example of converting CO, a type of exhaust gases emitted by vehicles on roads that needs to be cleaned for the environmental purpose. We find that the excess electrons on defect sites of AnO₂ enhanced the catalytic activity of CO conversion compared to the pristine AnO₂ surface.