fig2

Figure 2. (A) Schematic diagram of MXene species. Reproduced with permission from Ref.^[20]. Copyright 2014 Wiley-VCH. (B) SEM image of multi-layer MXene. Reproduced with permission from Ref.^[22]. Copyright 2021 Springer Nature. (C) TEM image of MXene with few or single layers. Reproduced with permission from Ref.^[23]. Copyright 2021 Springer Nature. (D) AFM image of single-layer MXene. Reproduced with permission from Ref.^[24]. Copyright 2019 Elsevier.