Synthesis of Nitrogen-Sulfur Co-Doped Ti3C2Tx MXene with Enhanced Electrochemical Properties

Through material innovation, nanoscale structural design and hybrid manufacturing methods, great efforts have been made in developing high-performance energy storage systems. These devices can be comprised of two-dimensional (2D) nanomaterials, such as MXene, and show promise for use in energy storage devices. In order to achieve better electrochemical properties of MXene, one crucial technique is to modify its structure by introducing defects or heteroatom dopants, which may expand the interlayer spacing and increase the ion transfer kinetics during the charge/discharge process. Here, a modified two-step multi-element strategy is explored utilizing ammonium citrate as intercalant and nitrogen source to enhance the level of heteroatom doping during annealing of MXene with sulfur. The resulting nitrogen/sulfur co-doped MXene displayed enhanced gravimetric capacitance (495 F g−1 at 1 A g−1), outstanding rate capability (180 F g−1 at 10 A g−1) and excellent cycle stability (98% retention after 6000 charge/discharge cycles). The synthesis of NS-MXene reveals a novel and facile multi-heteroatom pathway for functionalizing Ti3C2Tx MXene and demonstrates the potential variety of this family of modified MXenes that has yet to be explored, as well as unveils great promise for use in applications such as high performance supercapacitors.