文摘
Whether PuO2 could be further oxidized is a very important topic in Pu chemistry. Experiments on its oxidation have not completely demonstrated the existence of higher oxides. Here, the reaction energies of PuO2 with a series of molecules and their radiation-induced radicals and products are systematically predicted using first-principles calculations. The results show that F2 can react with PuO2, indicating the existence of higher-valence Pu in PuO2-based materials. Moreover, the formations of PuO2.25, PuO2.25H0.25, and PuO2.5H0.5 by the reactions of PuO2 with O鈥?/sup> and OH鈥?/sup> radials are exothermic. However, from the reaction energies of the reactions between hyperstoichiometric Pu oxides and two radicals, PuO2+xHx, instead of PuO2+x, are deduced to be the experimentally observed products in the kinetically favorable environments. The widely discussed PuO2+x act only as the intermediate products. Electronic structures of these hyperstoichiometric Pu oxides also reveal that PuO2+xHx are more stable than PuO2+x.