Boosting redox kinetics in CoS/Ti₃C₂ heterostructure via interfacial charge redistribution for high-energy-density supercapacitors

Supercapacitors are indispensable for next-generation energy storage, achieving high energy density and long-term durability remains a formidable challenge. Conventional CoS suffers from poor conductivity, while Ti₃C₂ faces severe restacking. Herein, we report a novel synthesis strategy that integrates metal-organic framework (MOF) growth with electrostatic self-assembly to construct heterojunction of CoS nanotubes coated with ultrathin Ti₃C₂ nanofilms. Material characterization via SEM, TEM, XRD, and XPS systematically confirms the heterostructure formation, and chemical composition. This rational design synergistically leverages CoS high pseudocapacitance and Ti₃C₂ metallic conductivity while the heterostructure mitigates restacking, enhances charge transfer, and stabilizes interfacial interactions. Density functional theory (DFT) calculations reveal strengthened OH^- adsorption at the Co-Ti interface (E_ad = 1.106 eV). Consequently, the CoS/Ti₃C₂@CC delivers a remarkable specific capacitance of 1034.21 F g^-1 at 1 A g^-1. Assembled into a supercapacitor, CoS/Ti₃C₂@CC//AC achieves a high energy density of 74.22 Wh kg^-1 at 800 W kg^-1, maintaining 89.13% initial capacitance after 10,000 cycles. Significantly, it exhibits a remarkably low leakage current (0.23 μA) and ultra-prolonged voltage retention (47.14% after 120 h), underscoring exceptional durability. This work pioneers a rational heterostructure engineering strategy by integrating MOF-derived architectures with conductive MXene nanofilms, offering critical insights for the development of ultradurable supercapacitor.