First principles studies of oxygen adsorption on the γ-U (1 1 0) surface and influences of Mo doping
First principles studies of oxygen adsorption on the γ-U (1 1 0) surface and influences of Mo doping
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DOI：
10.1016/j.commatsci.2020.109633
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发表时间：
2020-06
影响因子：
3.3
通讯作者：
X. Tian;Yu Wang;Lingshan Li;Mingde Wu;You Yu
中科院分区：
文献类型：
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作者：
X. Tian;Yu Wang;Lingshan Li;Mingde Wu;You Yu
采用从头算分子动力学（AIMD）和密度泛函理论（DFT）方法，研究了氧在清洁和Mo掺杂的γ-U（110）表面上的吸附动力学和能量学. AIMD模拟表明，O2将解离成单独的O原子，最终吸附在表面上。Mo的掺杂改变了O原子的最终吸附位置。另外，温度可以加速O 2在γ-U（110）表面的解离，吸附能的计算表明O原子在γ-U（110）表面的最佳吸附位置是短桥位，其次是三重空洞位. Mo的掺杂降低了所有吸附位的吸附能。Mo掺杂时，O原子的最佳位置仍然是短桥。但是，第二优选吸附位点变成长桥。对于清洁和Mo掺杂的表面，顶部是原子氧的最不优选的吸附位点。通过对扩散路径的计算，发现Mo掺杂提高了O原子在表面扩散的能垒。由计算的偏聚能发现，Mo原子更倾向于位于γ-U的“体”中而不是表面的顶层。
By ab initio molecular dynamics (AIMD) simulations and density-functional theory (DFT) calculations, we studied the kinetics and energetics of oxygen absorption on clean and Mo-doped γ-U (1 1 0) surface. The AIMD simulations shows that O2will dissociates into separate O atoms, which are finally adsorbed on the surface. The doping Mo can change the final adsorption sites of O atoms. In addition, we found that temperature can accelerate O2dissociation on γ-U (1 1 0) surface.The calculation of adsorption energies shows that the most preferred site for O atoms on the γ-U (1 1 0) surface is the short bridge site, followed by the 3-fold hollow. The doping Mo will decrease the adsorption energies of all the adsorption sites. With Mo-doping, the most preferred site for O atom is still short bridge. But, the second preferred adsorption site become long bridge. For clean and Mo-doped surfaces, the on-top is the least preferred adsorption site for atomic oxygen. Through calculations of diffusion pathways, we found Mo-doping raise the energy barrier for O atom diffusion on the surface. By the calculated segregation energies, it is found that the Mo atom prefers to locate in γ-U “bulk” rather than the top layer of the surface.