Grover Payal, Ferch Laura S, Schreckenbach Georg
Department of Chemistry , University of Manitoba , Winnipeg , MB R3T 2N2 , Canada.
J Phys Chem A. 2020 Feb 27;124(8):1522-1534. doi: 10.1021/acs.jpca.9b10888. Epub 2020 Feb 17.
Adsorption of actinide (Ac = U, Np, Pu) complexes with environmentally relevant ligands on silicene and germanene surfaces has been investigated using density functional theory to determine the geometrical, energetic, and electronic properties. Three types of ligands for each central metal atom are considered: OH, NO, and CO with common oxo ligands in all cases. Among these, carbonate complexes show the strongest adsorption followed by hydroxide and nitrate. Two types of model, cluster and periodic models, have been considered to include the short- and long-range effects. The cluster and periodic models are complementary, although the former has not yet been widely used for studies of 2D materials. Two cluster sizes have been investigated to check size dependency. Calculations were performed in the gas phase and water solvent. On the basis of the adsorption energy, for the CO and OH ligands, the bond position between two Si atoms in the silicene sheet is the most strongly adsorbed site in the cluster model for silicene whereas in the periodic model these complexes exhibit strong binding on the Si atom of the silicene surface. The Ac complexes with the NO ligand show strong affinity at the hollow space at the center of a hexagonal ring of silicene in both models. The H site is most favorable for the binding of complexes on the germanene cluster whereas these sites vary in the periodic model. Electronic structure calculations have been performed that show a bandgap range from 0.130 to 0.300 eV for the adsorption of actinide complexes on silicene that can be traced to charge transfer. Density of states calculations show that the contribution of the nitrate complexes is small near the Fermi level, but it is larger for the carbonate complexes in the silicene case. Strong interactions between Ac complexes and silicene are due to the formation of strong Si-O bonds upon adsorption which results in reduction of the actinide atom. Such bonding is lacking in germanene.
利用密度泛函理论研究了锕系元素（Ac = U、Np、Pu）与环境相关配体形成的配合物在硅烯和锗烯表面的吸附情况，以确定其几何、能量和电子性质。针对每个中心金属原子考虑了三种类型的配体：OH、NO和CO，所有情况下均带有常见的氧代配体。其中，碳酸根配合物的吸附最强，其次是氢氧化物和硝酸盐。考虑了两种类型的模型，即簇模型和周期性模型，以纳入短程和长程效应。簇模型和周期性模型是互补的，尽管前者尚未广泛用于二维材料的研究。研究了两种簇尺寸以检查尺寸依赖性。计算在气相和水溶剂中进行。基于吸附能，对于CO和OH配体，在硅烯簇模型中，硅烯片中两个Si原子之间的键位置是吸附最强的位点，而在周期性模型中，这些配合物在硅烯表面的Si原子上表现出强结合。在两种模型中，带有NO配体的Ac配合物在硅烯六边形环中心的中空处表现出强亲和力。H位点最有利于配合物在锗烯簇上的结合，而在周期性模型中这些位点有所不同。进行的电子结构计算表明，锕系元素配合物吸附在硅烯上时，带隙范围为0.130至0.300 eV，这可归因于电荷转移。态密度计算表明，在费米能级附近，硝酸盐配合物的贡献较小，但在硅烯情况下，碳酸根配合物的贡献较大。Ac配合物与硅烯之间的强相互作用是由于吸附时形成了强Si - O键，这导致锕系原子被还原。锗烯中缺乏这种键合。
