Unveiling the dual tunability of dimension and pore structure in MAX-derived carbon via molten salt electrolysis

3D construction or pore-forming of carbon nanosheets brings the materials exceptional energy storage performance. However, these strategies involve complicated procedures and challenging conditions. Herein, based on the structural regulation of a MAX phase, a facile method was proposed to prepare MAX-derived carbon (MDC) with dual tunability of dimension and pore structure via molten salt electrochemical etching-gaseous sulfur delamination coupling. Polyhedral structure Ti 2 SC and highly oriented structure Ti 2 SC were transformed into 3D Mesopore carbon nanoshells (3D Meso-CNSL) and 2D Mesopore carbon nanosheets (2D Meso-CNST) in one step. By matching the decomposition voltage of TiCl x with that of PS-Ti 2 SC, Cl 2 gas generated in situ was employed to enhance the porosity of the 3D Meso-CNSL, resulting in the formation of 3D meso/macro-porous carbon nanoshells (3D Meso/Macro-CNSL) with doubled pore volume (1.45 cm 3  g −1 ) and specific surface area (649.97 m 2  g −1 ). The 3D Meso/Macro-CNSL exhibits excellent capacity performance and cycle stability under high current density. The capacities are 674.8 mAh g −1 and 501.5 mAh g −1 after 1000 cycles at 5 A g −1 and 10 A g −1 , respectively. It is the first report on the direct delamination of MAX phases into 3D nanomaterials, presenting a new pathway for the precise regulation of the nanostructure of the MDCs.