fig18

Figure 18. (A) (i) Models of planar graphite layers with various interlayer distances of 3.6, 3.8 and 4.0 Å, (ii) models of single-layer graphene with different compression ratios of 0 %, 10 %, 30 % and 50 %, (iii) the most stable adsorption configuration for Na⁺ in planar graphite layers, (iv) the most stable adsorption configuration for Na⁺ in the in-plane and out-plane of single-layer curved-graphene, (v) the binding energy of Na⁺ in different interlayer distances (3.4 to 5.2 Å) and (vi) Na⁺ on graphene with different compression ratios (0 % to 50 %)^[28] (Copyright 2023 Elsevier B.V). (B) (i) Atomic structure of Na⁺ absorbed on pure graphene. (ii) graphene with mono-defect. (iii) bi-defect, (iv) tri-defect, (v) O doping, (vi) and O/mono-defect doping^[119] (Copyright 2019, Elsevier Ltd). (C) Theoretical simulations and related results. Na atom was absorbed on the (i) carbon structures with di-vacancy defects (type1, type2, type3) and single vacancy defects (type4). (ii and iii) Top view and side view of the difference in electron density of Na absorbed by different carbon structures. The yellow and blue regions represent the increased and decreased electron density, respectively. The brown and yellow balls represent the C and Na atoms, respectively^[120] (Copyright 2020, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim).