Local Coordination Modulation of Competitive H2 /O2 Adsorption and Oxyg en-Coverage-Dependent H2 Adsorption on a Transition-Metal-Doped γ-U(100) Surface

摘要: Early corrosion of uranium materials in oxygen and hydrogen-containing environments depends on the competition between oxidation and hydrogenation processes; however, the mechanism by which TM alloying regulates the relative adsorption of H2 and O2 and their subsequent reactions remains unclear. This study combines density functional theory (DFT) with interpretable machine learning (DFT-ML) to investigate the effects of TM doping on the γ-U(100) surface regarding the adsorption of H2 and O2. By comparing the relative adsorption affinities of H2 and O2 across different TM systems, the study reveals how TM alloying modulates the early oxidation-hydrogenation competition processes on the surface. Six TM-doped systems were randomly selected for H2 and O2 adsorption calculations. The results show that TM doping generally weakens the adsorption of both H2 and O2; nevertheless, O2 consistently exhibits a stronger thermodynamic adsorption preference than H2. HydEnsemble and OxydEnsemble, constructed on the basis of adsorption sites, TM properties and local geometric descriptors, achieved R2 values of 0.977 and 0.975 respectively on the test set, and identified site type and local distortion as the primary controlling factors for H2 adsorption, whilst O2 adsorption was found to be more sensitive to angular coordination. Further screening was carried out to identify Ru-doped surfaces with weaker H2 affinity whilst retaining strong O2 adsorption. Further calculations indicate that oxygen coverage, by restructuring the coupling between the U-f/U-d, Ru-d and O-p states, makes H2 adsorption dependent on coverage and adsorption sites. This paper provides a theoretical basis for understanding the mechanisms of early oxidation-hydrogenation coupling in uranium materials and for the control of alloying.