Fig. 3

a Flow chart of etching Ti₃AlC₂ powders to obtain exfoliated 2D Ti₃C₂T_x layers [27]. Copyright 2017, Elsevier. b Typical SEM image of Ti3AlC2 powders before HF etching [28]. c The SEM image obtained after the removal of ‘Al’ by HF etching [28]. Copyright 2019, American Chemical Society. d SEM and e TEM images of the exfoliated 2D Ti3C2Tx flakes after sonication [29]. Copyright 2020, American Chemical Society. f HRTEM image of bilayer Ti3C2Tx and its corresponding atomistic model [13]. Copyright 2011, Wiley–VCH. g HRTEM image showing the exfoliated 2D Ti3C2Tx after sonication, and the interlayer spacing is characterized to be 9.82 Å [31]. Copyright 2018, Wiley–VCH. h HRTEM image of Ti3C2Tx with an equiangular lattice spacing of ∼2.54 Å, which matches well with the result obtained by DFT calculation (Table 1) [32]. Copyright 2018, Wiley–VCH