First-principles study of water adsorption and dissociation on the UO2 (1 1 1), (1 1 0) and (1 0 0) surfaces

Effects of Zr doping on the surface energy and surface structure of UO2: Atomistic simulations

“…The (1 0 0) surface of undoped UO 2 consistently exhibits the highest surface energies, followed by the (1 1 0) surface, and finally the (1 1 1) surface, which has the lowest values. These relative trends in surface energy of undoped UO 2 as a function of crystallographic orientation are in good agreement with those resulting from MD and density functional theory (DFT) calculations in the literature [19,[31][32][33]20,36], as well as with values predicted by the empirical potential method in our previous work [37]. Generally speaking, the most stable surface is the one with the lowest surface energy, i.e.…”

“…Surface energy values of undoped UO 2 obtained from our simulations are presented in Table 2. The others theoretical results [19,20,[31][32][33]36,37] available are also listed for comparison. It indicates that the surface energy depends on the crystallographic orientation.…”

“…widely used to study the point defects formation energies and the stability of defect clusters in UO 2 fuel [26][27][28][29]. Sometimes scholars also applied this method to investigate the surface energy of cubic UO 2 and the absorption of molecules on the surface of UO 2 and other oxide nuclear fuels [30][31][32][33][34]. Although this method is very successful for studying the point defect properties and the surface behavior of UO 2 fuel, it is very difficult to calculate the system which contains more than a few hundred atoms and predict the changes in surface energies and surface structures resulting from the doping with a little mount of foreign elements.…”

Comparison of the Stability of Functionalized GaN and GaP

“…This changes post-soaking as the ratios from S4 confirm a difference in oxide composition (sub-oxide to Ga 2 O 3 ), which is likely a result from the spontaneous dissociation of water onto the surface. [63,64] Deconvolution of the O1 s spectra (SI, S6) confirms the initial hydroxyl terminated oxide setup (represented in Scheme 1) in addition to the migration of sub-oxides to Ga 2 O 3 formations following soaking. This was supported by the shifting of the O1 s spectra from 533 eV (corresponding to -OH termination) to 531 eV (corresponding to -O-type bonding).…”

Transuranic Computational Chemistry

“…OurP BC and PEECM DFT agree on this, as does earlier PBC DFT work of Bo et al on UO 2 / water. [28] By contrast, we predict that the most stable adsorptions on the {110} and {100} surfaces are either mainly or fully dissociative, producing ah ydroxylated monolayer.W eh ave also calculated the temperature at which water would desorb from our three surfaces as af unction of pressure, [26] concluding that there would be no water on the {111}s urfaceo fP uO 2 in the storage cans, as the temperatures within the cans are high. Stakebake found (experimentally) two distinct temperature ranges for water desorbing from PuO 2 .…”