Sequentially Bridged Ti₃C₂T_x MXene Sheets for High Performance Applications

Abstract

The outstanding electrical conductivity and high specific capacitance of 2D Ti3C2Tx MXene have made them promising materials for a wide range of applications including wearable electronics, energy storage, sensors, and electromagnetic interference shielding. However, the fabrication of MXene architectures, both pure and composite, often results in a trade‐off in properties. Here, it is reported that sequential bridging of MXene sheets significantly enhances the mechanical properties of its free‐standing films, with improvements in strength and toughness of up to ≈339 MPa and ≈12.0 MJ m−3, respectively, while simultaneously retaining both high conductivity (≈4850 S cm−1) and volumetric capacitance (≈1220 F cm−3). This sequential bridging strategy permits surface modification of MXene sheets while still yielding stable colloidal dispersions so that the subsequent MXene films comprise of aligned, evenly‐spaced, and interconnected sheets, which are critical for the development of robust energy storage devices and other high performance applications.

Inducing liquid crystallinity in dilute MXene dispersions for facile processing of multifunctional fibers

“…Single-layer MXene dispersions were prepared by selectively etching aluminum from the Ti 3 AlC 2 MAX phase through a minimally intensive layer delamination (MILD) method described in our previous studies. 14,18,43–47 Details of the MXene synthesis and full characterization data are provided in the ESI †. Briefly, scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD) data demonstrate successful etching of aluminum layers and exfoliation of MXene sheets (Fig.…”

“…6,7 These remarkable properties make MXenes excellent candidates for a wide array of applications including but not limited to energy storage, 8,9 sensors, 10,11 and electromagnetic interference shielding. 12,13 In order to realize these applications, MXenes are typically solution-processed into films, 14,15 fibers, 11,16,17 and foams. 18,19 However, controlling the degree of sheet ordering, which is critical to performance, using conventional fabrication methods remains a challenge.…”

“…18,19 However, controlling the degree of sheet ordering, which is critical to performance, using conventional fabrication methods remains a challenge. 14,15,20…”

“…16,28,29 These fibers possess significantly higher electrical conductivity (∼7800 to 12 500 S cm −1 ) than fibers based on other 2D nanomaterials such as graphene (∼384 S cm −1 ). 30 LC MXene has also enabled the blade coating of large films (1 m long) which, unlike their vacuum-filtered counterparts, 7,14,31 are composed of densely stacked and highly aligned MXene. 15 Such an ordered nanostructure resulted in films with record tensile strength (∼570 MPa) and high electrical conductivity (∼12 300 S cm −1 ), 25- and 2.3-fold higher than non-LC MXene films, respectively.…”

“…, Ti-complexes), 38 is well known to effectively enhance inter-MXene sheet connectivity. 14,38 Upon dispersion, the rigid and highly crystalline CNCs also possess the inherent tendency to self-associate and become LC. 39,40 Unlike other materials such as cellulose fibrils, 7,41 the addition of a rigid particle such as CNC to MXene dispersions improves anisotropic ordering, inducing liquid crystallinity in MXene at an effective lower critical transition concentration ( C T ) than previously reported.…”