Fe改性石墨烯对沙林分子的吸附性质研究

发布时间：2018-06-27 01:48

本文选题：石墨烯 + 沙林　；参考：《长春大学》2017年硕士论文

【摘要】：近年来,曾在战争及恐怖袭击中被广泛使用的化学毒剂对人类及国家安全造成了极大伤害,因此,如何有效消除这一化学毒剂成为科研工作者和国家安全面临的主要挑战。有效消除化学毒剂一个行之有效的办法就是选择合适的吸附材料。石墨烯具有超高的比表面积、良好的热学和化学稳定性、易于合成、成本低,而生产中形成的缺陷、杂质、化学官能团又可能会创造更多的吸附活性位置从而有效提高其吸附活性,因此,成为极具前景的吸附材料。众所周知,理想石墨烯对原子或分子的吸附为弱的物理吸附,要想实现石墨烯基纳米材料优异的吸附性能,必须对理想石墨烯进行改性,提高其吸附活性。同传统的贵金属相比,铁(Fe)原料丰富,成本低,环境友好,反应效率高。因而我们选择过渡金属Fe及其团簇对本征石墨烯进行修饰,进而将其作为中间媒介去吸附沙林分子。从理论上模拟Fe改性石墨烯对沙林气体的吸附作用,通过计算各种吸附情况下的相关性质,揭示其吸附机制。有利于明确和理解沙林分子的识别、清除、防护、从有毒向无毒转化等问题,并将为制备安全、有效的化学毒剂防护系统提供理论依据。本文通过基于密度泛函理论的第一性原理计算方法,系统研究了本征石墨烯吸附沙林分子、Fe及其二元团簇改性石墨烯吸附沙林分子以及石墨烯对三元及四元Fe团簇的吸附性质。计算了体系吸附能、电子态密度和密立根电荷密度等相关性质。通过对比分析我们的计算结果可知,本征石墨烯对沙林的吸附作用为弱的物理吸附;Fe原子的引入,明显增强了石墨烯基底对沙林的吸附作用,沙林分子与Fe改性石墨烯体系之间存在明显的电荷转移;同单个Fe原子改性石墨烯相比,二元Fe团簇改性石墨烯对沙林分子的吸附能明显增大,导致沙林分子态密度更加弥散,并且向低能方面移动,沙林分子与石墨烯基底之间的电荷转移增多;Fe原子团簇与本征石墨烯的相互作用强烈依赖于团簇的形状和尺寸,三元Fe团簇易于以三角形平面垂直于石墨烯表面进行吸附,而四元Fe团簇易于以四面体形状吸附在石墨烯表面。即:随着Fe原子个数增加,体系吸附能增大,Fe团簇与石墨烯基底之间的电荷转移增强,吸附作用增强。
[Abstract]:In recent years, chemical agents which have been widely used in war and terrorist attacks have caused great harm to human and national security. Therefore, how to effectively eliminate this chemical agent has become a major challenge for researchers and national security. One effective way to eliminate chemical agents is to select suitable adsorption materials. Graphene has a high specific surface area, good thermal and chemical stability, easy synthesis, low cost, while the production of defects, impurities, Chemical functional groups may also create more sites of adsorption activity to effectively improve their adsorption activity, therefore, become a very promising adsorption materials. It is well known that the adsorption of ideal graphene to atoms or molecules is weak physical adsorption. In order to achieve excellent adsorption performance of graphene based nanomaterials, it is necessary to modify ideal graphene to improve its adsorption activity. Compared with the traditional precious metals, iron (Fe) is rich in raw materials, low in cost, environmentally friendly and high in reaction efficiency. Therefore, the transition metal Fe and its clusters were chosen to modify the intrinsic graphene, which was then used as an intermediate to adsorb sarin molecules. The adsorption mechanism of Fe modified graphene on sarin gas was studied by calculating the related properties of various adsorption conditions. It is helpful to clear and understand the identification, removal, protection and conversion from toxic to non-toxic of sarin molecules, and will provide theoretical basis for the preparation of safe and effective chemical agent protection system. Based on the density functional theory (DFT), the adsorption properties of ternary and quaternary Fe clusters by graphene adsorbed on sarin and its binary cluster modified graphene are studied systematically in this paper. The adsorption energy, electron density of state and Millikan charge density were calculated. By comparing and analyzing our calculation results, it can be seen that the adsorption of sarin by intrinsic graphene is a weak physical adsorption of Fe atoms, which obviously enhances the adsorption of sarin on graphene substrate. Compared with the single Fe atom modified graphene, the adsorption energy of the binary Fe cluster modified graphene on the sarin molecule is obviously increased, which leads to the diffusion of the density of states of the sarin molecule. The charge transfer between the sarin molecule and the graphene substrate increases and the interaction between the Fe cluster and the intrinsic graphene is strongly dependent on the shape and size of the cluster. Ternary Fe clusters are easily adsorbed on graphene surface in triangular plane, while quaternary Fe clusters are easily adsorbed on graphene surface in the shape of tetrahedron. That is, with the increase of the number of Fe atoms, the adsorption energy of the system increases with the increase of the charge transfer between the Fe cluster and the graphene substrate, and the adsorption effect is enhanced.
【学位授予单位】：长春大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：O647.3

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