Construction of Monolayer Ti 3 C 2 T x MXene on Nickel Foam under High Electrostatic Fields for High-Performance Supercapacitors.

Ti 3 C 2 T x MXene, as a common two-dimensional material, has a wide range of applications in electrochemical energy storage. However, the surface forces of few-layer or monolayer Ti 3 C 2 T x MXene lead to easy agglomeration, which hinders the demonstration of its performance due to the characteristics of layered materials. Herein, we report a facile method for preparing monolayer Ti 3 C 2 T x MXene on nickel foam to achieve a self-supporting structure for supercapacitor electrodes under high electrostatic fields. Moreover, the specific capacitance varies with the deposition of different-concentration monolayer Ti 3 C 2 T x MXene on nickel foam. As a result, Ti 3 C 2 T x /NF has a high specific capacitance of 319 mF cm -2 at 2 mA cm -2 and an excellent long-term cycling stability of 94.4% after 7000 cycles. It was observed that the areal specific capacitance increases, whereas the mass specific capacitance decreases with the increasing loading mass. Attributable to the effect of the high electrostatic field, the self-supporting structure of the Ti 3 C 2 T x /NF becomes denser as the concentration of the monolayer Ti 3 C 2 T x MXene ink increases, ultimately affecting its electrochemical performance. This work provides a simple way to overcome the agglomeration problem of few-layer or monolayer MXene, then form a self-supporting electrode exhibiting excellent electrochemical performance.