Fig. 1: Preparation and characterization of LB-Ti₃C₂T_x.

a Schematic of the preparation of LB-Ti₃C₂T_x. After Lewis-basic halides treatment, Ti₃C₂T_x is intercalated by desolvated Na⁺ and K⁺, inducing the increased interlayer spacing. Simultaneously, the surface -F termination is replaced by desolvated halogen anions. b The process of the nucleophilic substitution between desolvated Br^- and F atoms (red balls: titanium, black balls: carbon, yellow balls: fluorine, cyan balls: bromine, blue balls: sodium, silver ball: potassium). c, d SEM of multilayer Ti₃C₂T_x and LB-Ti₃C₂T_x. Scale bar 1 μm. e XRD patterns of multilayer Ti₃C₂T_x and LB-Ti₃C₂T_x. f Atomic-resolution high-angle annular dark-field (HAADF) TEM image and the corresponding atomic arrangement. Scale bar 1 nm. g Energy dispersive spectrum (EDS) elemental analysis (line scan) of LB-Ti₃C₂T_x. h High-resolution Br 3d XPS spectra of Ti₃C₂T_x and LB-Ti₃C₂T_x. After Lewis-basic halides treatment, the peaks of Ti-Br bonds appear and exhibit high intensity. Source data are provided as a Source Data file.