Ti3C2Tx/CDs@MnO2 Composite as Electrode Materials for Supercapacitors: Synthesis and Electrochemical Performance

Abstract MXenes are a kind of novel and interesting new materials, and carbon dots (CDs) are also concerned because of their processability, versatility, environmental protection and low cost. Both MXenes and CDs are chemically stable and have a large surface area and high electrical conductivity, which are promising alternative electrode materials for supercapacitors. Moreover, MnO₂ can also improve the energy density of the electrode materials. In this paper, Ti₃C₂Tx/CDs and Ti₃C₂Tx/CDs@MnO₂ composites were prepared by a hydrothermal method and their supercapacitor performance were also investigated by a series of electrochemical methods. From the CV profile in a three-electrode system, Ti₃C₂Tx/CDs@MnO₂ electrode exhibited a high specific capacitance of 281.3 F g⁻ ¹ at a scan rate of 5 mV s⁻ ¹, which was higher than that of Ti₃C₂Tx/CDs (160.3 F g⁻ ¹). The Ti₃C₂Tx/CDs showed a good cycling stability with a capacitance retention of 82.38% after 10,000 cycles. Meanwhile, a symmetric supercapacitor was successfully assembled using Ti₃C₂Tx/CDs@MnO₂ as electrodes, with an energy density of 5.77 Wh kg⁻ ¹ at a corresponding power density of 120 W kg⁻ ¹. This work offers a theoretical foundation and a technological path for synthesizing highly effective ternary composite of MXene-based as energy storage materials.