X-ray photoelectron spectroscopy study of CO2 reaction with polycrystalline uranium surface

The adsorption of CO2 on 'clean' depleted polycrystalline uranium metal surface has been studied by X-ray photoelectron spectroscopy (XPS) at 300 K. The 'clean' surface were prepared by Ar+ ion sputtering under ultra-high vacuum (UHV) condition with a base pressure 6.7 x 10-8 Pa. The result s shows that adsorption of CO2 on 'clean' uranium metal took place in total dissociation, and leads to the formation of uranium dioxide, uranium carbides and free carbon. The total dissociation of CO2 produced carbon, oxygen species, CO22- and CO32- species. The diffusion tendency of carbon was much stronger than that of oxygen, and led to form a carbide in oxide-metal interface while the oxygen remained on their surface as an oxide