Nb2CTx MXene integrated DyMn2O5 composites: tailored particle size and enhanced capacitance for high performance pseudocapacitors

Abstract

Nb₂CT_x, 2D niobium carbide, belongs to the MXene family obtained from Nb₂AlCT_x through selective etching of the Al layer using a non-toxic aqueous KOH solution as an alternative to the hazardous HF etching process. MXene is an emerging material for supercapacitor electrodes due to its distinctive layered structure, large surface area, superior electrical conductivity, and exceptional chemical stability. Owing to the significant energy of the MXene layers, they have a tendency to restack, which limits the effective utilization of the interlayer space for energy storage. Consequently, expanding the interlayer spacing of MXene has become a key research focus to improve its electrochemical performance. Currently, the interlayer spacing of MXene is typically expanded by incorporating nanoparticles. Although numerous bi-metallic transition metal oxides have been explored for this application, only a limited number of rare earth-based bi-metallic oxides have been investigated. Nowadays, the interlayer spacing of MXene is enhanced through the incorporation of nanoparticles. Different bi-metallic transition oxides have been used for this purpose, but very few rare earth-based bi-metallic oxides have been investigated. So in this study, we have synthesized a bi-metallic DyMn₂O₅/Dy₂O₃/MXene nanocomposite using a hydrothermal method. X-ray diffraction (XRD) analysis was conducted to determine the crystalline structure and phase purity of the materials. In addition, Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) were performed to investigate the functional groups, chemical bonding and multiple oxidation states in the composites, respectively, providing further confirmation of successful synthesis. Scanning electron microscopy (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) was employed to analyze the surface morphology and confirm the cubic-shaped pellet-like nanoparticles on the MXene layers, as well as to verify the elemental composition and uniform distribution of constituent elements. The optimized electrode material demonstrates a marvelous specific capacity of 362.92 C g⁻¹ at a current density of 1 A g⁻¹, along with excellent cycling stability. An asymmetric supercapacitor is fabricated using the DyMn₂O₅/Dy₂O₃/MXene nanocomposite as the anode and activated carbon as the cathode. The assembled device achieves an energy density of 46.25 W h kg⁻¹ at a power density of 705 W kg⁻¹, retaining 70.56% of its initial capacitance after 10 000 charge discharge cycles at 2 A g⁻¹. This study introduces an efficient hydrothermal method for the synthesis of an innovative rare earth and MXene-based nanocomposite with controlled particle size for the electrode of supercapacitors.