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中国物理学会期刊

    氧原子在氟化石墨烯上扩散的第一性原理计算

    First-principles calculations of O-atom diffusion on fluorinated graphene

    CSTR: 32037.14.aps.72.20221630
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    • 石墨烯的氟化是改善石墨烯涂层腐蚀防护能力的有效方法之一. 本文使用NEB过渡态搜索方法研究了O原子在完全氟化石墨烯(CF)和部分氟化石墨烯(C 4F)上的扩散和穿透行为, 分析F原子对石墨烯薄膜抗腐蚀能力的影响. 计算结果显示, F原子的吸附能有效抑制O原子在石墨烯上的扩散, C 4F上O原子的表面扩散能垒显著提高, CF内O原子的水平扩散能垒更是高达2.69 eV. 而且F原子的增加使得C原子层对O原子穿透的阻隔能力减小, 在CF中, O原子的穿透主要受到F原子层的阻隔. 此外采用第一性原理计算方法计算了纯石墨烯、CF和C 4F薄膜与Cu(111)表面的界面粘附功以及电子结构. 计算表明, 相比于纯石墨烯, CF和C 4F能更好地与基底结合, 界面粘附功随着F原子的吸附浓度增大而提高. Cu/C 4F和Cu/CF界面的电荷转移均增加, 其中Cu/C 4F界面的电荷转移更多, C 4F与Cu(111)表面的部分Cu原子生成Cu—C键.

      Fluorination of graphene is one of the most effective methods to improve the corrosion protection of graphene coatings. In this work, the diffusion and penetration behaviors of O atoms on fully fluorinated graphene (CF) and partially fluorinated graphene (C 4F) are investigated by using the method of searching for NEB transition state . The effects of F atoms on the corrosion resistance of fluorinated graphene films are also analyzed r. The results show that the adsorption of F atoms can effectively inhibit the diffusion of O atoms on graphene. On C 4F, the F atoms are distributed in a para-top position, which greatly increases the surface diffusion energy barrier of O atoms. Moreover, it is difficult for the adsorbed O atoms to diffuse to different sp 2C rings through the obstruction of F atoms. The energy barrier of the horizontal diffusion of O atoms even reaches 2.69 eV in CF. And with the increase of F atoms, the stable structure of graphene is gradually destroyed, the ability of C-atom layer to bar the penetration behaviors of O atoms decreases greatly. Furthermore, the interfacial adhesion work of pure graphene, CF and C 4F films with Cu(111) surfaces are calculated, as well as the electronic structures of the composite interface are investigated by using first-principles calculations. The interfacial adhesion work of the Cu/G, Cu/C 4F and Cu/CF interfaces are 2.626 J/m 2, 3.529 J/m 2and 3.559 J/m 2, respectively. The calculations show that the bonding of C 4F and C 4F with Cu substrate are stronger than pure graphene with Cu substrate, and the interfacial adhesion work increases with the augment of F atom adsorption concentration. The calculation of the density of states also conforms that the interaction between Cu and C atoms of the Cu/C 4F interface is stronger than that at the Cu/CF interface. Bader charge analysis shows that the charge transfer at the Cu/C 4F interface and the Cu/CF interface increase comparing with that at the Cu/G interface, and Cu/C 4F interface has more charge transfer, in which Cu—C bonds are formed.

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