Facile synthesis of 2D Mo2TiC2@PDA/MnO2 composite-based electrode material for clean and efficient energy storage

Owing to their distinctive stacked layered structure, exceptional conductivity, large specific surface area, and abundance of redox active sites, two-dimensional transition carbon nitride, and metal carbides and nitrides efficiently store and transfer charges, thus becoming attractive electrode materials for supercapacitors. MXene-based supercapacitors are, however, seriously hindered by the low specific capacitance driven by severe self-discharge behavior and poor ambient stability due to oxidation. To overcome these limitations, herein, a Mo2TiC2@PDA/MnO2 composite was synthesized to functionalize a glassy carbon electrode (GCE) surface via a two-layer modification strategy, which enabled faster charge transfer and ion diffusion within the electrode material, thus boosting the capacitive performance of Mo2TiC2 MXene. The composite’s structure and morphology were confirmed by X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. Furthermore, the electrochemical behavior of the functionalized-electrodes was assessed by galvanostatic charge–discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS), which all revealed that Mo2TiC2@PDA/MnO2 can be a promising electrode material for supercapacitor. The Mo2TiC2@PDA/MnO2 modified electrode delivered a high specific capacitance of 573 Fg−1 at a current density of 1 Ag−1 and demonstrated superior cycling stability with 87.43% capacitance retention over 5000 cycles. This study shows that integrating Mo2TiC2, PDA, and MnO2 can significantly improve the capacitance, stability, and eco-friendly operation in supercapacitors. However, the current work does not evaluate the performance in portable or flexible devices, and future studies may address this limitation through full-cell assembly and real-world testing. Overall, the composite provides a strong foundation for next-generation energy storage applications.