Chlorine is a crucial radionuclide that must be removed in irradiated nuclear graphite. Understanding the interaction between chlorine and graphene-based materials is essential for studying the removal process of 36Cl from irradiated nuclear graphite. In this study, first-principle density functional theory (DFT) was utilized to investigate the adsorption characteristic of chlorine on the original and reconstructed edges of graphene-based materials. Based on the calculation of adsorption energy of the structures after each step of adsorption, the most energetically favorable adsorption routes at four types of edge were determined: Along the armchair edge and reconstructed zigzag edge, the following adatoms would be adsorbed to compensate the distortion induced by the previously adsorbed atom. Meanwhile at the original zigzag edge, chlorine atoms would be adsorbed alternatively along the edge to minimize the repulsion between two adjacent chlorine atoms. The chemical nature of the bonds formed as a result of adsorption was elucidated through an examination of the density of states (DOS) for the two adsorbed chlorine atoms and the carbon atoms attached. Furthermore, to assess the relative stability of the adsorption structures, formation energy of all energetically favorable structures following adsorption was computed. Consequently, the predominant adsorption structure was identified as the reconstructed armchair edge with two chlorine atoms adsorbed. The desorption process of 36Cl2 from the predominant structure following adsorption was simulated, revealing an energy barrier of 1.14 V for desorption. Comparison with experimental results suggests that the chlorine removed from reconstructed armchair edges significantly contributes to the low-temperature removal stage of 36Cl from irradiated nuclear graphite.

The interaction between chlorine and the edge of graphene-based material: a first-principles study
    Abstract
    1 Introduction
    2 Methods
    3 Results and discussion
        3.1 Adsorption of chlorine at different edges
        3.2 Bonding nature between chlorine and edge
        3.3 Relative stability of the structures after adsorption.
        3.4 Desorption of chlorine from edge of graphene-based materials
    4 Conclusion
    Acknowledgements 
    References

• Ke Deng(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China) Corresponding author
• Qin Zhang(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China)
• Lixiao Zhu(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China)
• Youshi Zeng(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China)
• Wei Liu(Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, China)