High-Capacity Ti 3 C 2 T x MXene Electrodes Achieved by Eliminating Intercalated Water Molecules Using a Co-solvent System.

Synthesizing layered transition-metal carbides, MXenes, with a mesoporous structure remains challenging but is highly useful because it converts the laminated two-dimensional structures into versatile porous materials. Hydrogen bonds between intercalated H 2 O molecules and oxygen terminal groups on the surface are formed in aqueous solution processes, and this is a determining factor of surface area. We developed an extraction method to remove intercalated water molecules based on a simple intermolecular force attraction strategy in a co-solvent system using a combination of polar-protic/-aprotic and non-polar solvents. As a result, self-aggregated mesoporous Ti 3 C 2 T x was realized without any additives. The dipole-dipole interaction between H 2 O and CHCl 3 molecules under non-polar solvent conditions assists the extraction of intercalated H 2 O from the MXene suspension, which can form a self-aggregated morphology (not re-stacked horizontally). The process yields Ti 3 C 2 T x with a layered structure of embedded mesopores and a specific surface area that is 13-fold higher than that of standard MXene. Electrodes made with the resulting MXene exhibited a larger specific capacitance of 224 F/g (1 A/g), with an improved cyclic retention of 96.4%@10,000 cycles. This intermolecular attraction-induced approach, involving the manipulation of morphology, is simple to mass-produce and can be used for MXene-based electrochemical applications.