MXene/Biomass-derived activated carbon composite for supercapacitor applications

Abstract

Two-dimensional (2D) MXenes (e.g., Ti₃C₂Tₓ) have garnered significant interest in supercapacitor applications because of their outstanding conductivity, hydrophilicity, and charge storage capabilities. However, the inherent tendency of MXenes to restack and agglomerate severely limits electrolyte accessibility and reduces their electrochemical performance. To address this limitation, creating three-dimensional (3D) porous architectures by introducing interlayer spacers has emerged as an effective strategy. Conventionally, expensive spacers like graphene, carbon nanotubes, polypyrrole, reduced graphene oxide, etc., have been employed, which restricts scalability and cost-efficiency. Herein, we present a sustainable and cost-effective approach by synthesizing porous activated carbon (AC) derived from biomass waste (orange peels) and incorporating it as a spacer within Ti₃C₂Tₓ MXene layers. The resulting Ti₃C₂Tₓ/AC composite demonstrates enhanced structural stability through increased open spaces and expanded interlayer spacing (d = ∼1.1 nm), improved hydrophilicity (contact angle (CA): 13.46°), and superior electrolyte accessibility. Electrochemical evaluation in aqueous electrolyte shown a specific capacitance of 407 F g⁻¹ at 5 mV s⁻¹. Furthermore, the fabricated all solid-state supercapacitor (ASSC) showed the rate capability of up to 5000 cycles with an outstanding 96.36 % coulombic efficiency and 92.98 % capacitance retention, proving long-term stability in an aqueous environment. Our study underscores the dual advantage of valorizing biomass waste for creating porous carbon and achieving scalable, environmentally friendly MXene composites with optimized electrochemical properties for supercapacitor applications in aqueous electrolyte.