Synthesis of restacking-free wrinkled Ti3C2T monolayers by sulfonic acid group grafting and N-doped carbon decoration for enhanced supercapacitor performance

Abstract Although Ti3C2Tx MXene is emerging as a new two-dimensional energy storage material with excellent physical and chemical properties, its surface termination and easy restacking have severely limited such a promising application. Herein, we reported a new modification strategy for Ti3C2Tx by grafting with sulfonic acid group and decoration with N-doped carbon (abbreviated as S–Ti3C2Tx@N–C), after which the interlayer spacing of the wrinkled Ti3C2Tx was effectively expanded with additive active sites, and the electrochemical performance was enhanced apparently. Based on a standard three-electrode system, the specific capacitance of S–Ti3C2Tx@N–C-700 °C (annealed at 700 °C) electrode was elevated to a high value as 260 F g−1 at a current density of 0.8 A g−1, about 3 times that of Ti3C2Tx, also higher than that of many other Ti3C2Tx-based materials in literature. Moreover, the S–Ti3C2Tx@N–C-700 °C electrode maintains 90% of the initial capacitance after 5000 cycles. This work provides a simple and efficient approach of the electrode modification suitable for further energy applications.