Computational studies of actinide adsorption on two-dimensional materials
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Date
2019-11
Authors
Payal
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Abstract
The research area of 2-dimensional (2D) materials came into existence with the discovery of graphene [1] that was awarded the Nobel Prize in Physics in 2010. Afterward, a wide range of 2D materials has been predicted theoretically. 2D materials hold promise for applications in various fields including solar energy conversion, water filters, biomedical applications etc. To further exploit the properties of these 2D materials, two methodologies have been considered in literature – adsorption, and doping. In the present study, silicene, germanene, and borophene which are two-dimensional allotropes of silicon, germanium, and boron respectively have been chosen because of their strong interactions with complexes as compared to graphene. Also, to build our expertise in chemistry occurring between heavy-elements and 2D materials, actinide complexes have been considered. The methodology for studying the adsorption of Ac-complexes on the silicene/germanene/borophene surfaces have followed a metal-centered and material-centered approach. The principal questions which will be answered in the present study are the strengths of adsorption, periodic trends for materials and the effect on the electronic structure of the three above mentioned 2D materials. (Band Gap). The Ac-complexes such as MO2(OH)2, MO2(NO3)2 and MO2CO3 where M= U, Np, and Pu have been adsorbed on Silicene and Germanene flakes as well as on the periodic surface. For borophene, only a periodic surface has been considered. Different conformations of adsorbed Ac-complex have been analyzed and the most stable conformation includes both mono-oxygen ligands of Ac-complex bind to two Si/B atoms of silicene and borophene respectively thus, leading to the reduction of central actinide metal atom. Such bonding is absent in Germanene. Further, there is a charge transfer occurring between the complex and 2D material in the direction from 2D material to Ac-complex resulting in small bandgap opening in 2D-surface. The geometrical parameters such as bond length, bond angles and the buckling parameter of the 2D surface have undergone huge changes as a result of interactions occurring between Ac-complex and silicene/germanene/borophene.
[1] Geim AK, Novoselov KS. The rise of graphene. In Nanoscience and Technology: A Collection of Reviews from Nature Journals 2010 (pp. 11-19).
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Keywords
Computational chemistry, 2 dimensional materials, actinides