Controlled oxidative polymerization of thiophene on oxidation-sensitive Ti3C2Tx MXene for enhanced supercapacitor performance

Integrating conducting polymers with Ti 3 C 2 T x MXene offers an attractive strategy for enhancing supercapacitor performance, yet direct oxidative polymerization remains challenging because the oxidants required for polymer formation simultaneously promote rapid MXene degradation. Herein, we demonstrate that successful aqueous in-situ polymerization depends on controlling the kinetic competition between polythiophene growth and oxidative degradation of MXene. Prolonged exposure to ammonium persulfate resulted in extensive oxidation of Ti 3 C 2 T x into anatase TiO 2 , whereas limiting the reaction time to ≤1.5 h preserved the layered MXene framework while enabling conformal polythiophene growth. Structural and spectroscopic characterization by XRD, TEM, FTIR, UV–Vis, Raman, and XPS confirmed preservation of the MXene architecture, successful polythiophene growth, and the formation of an electronically coupled MXene–polythiophene interface. Electrochemical measurements further revealed that the optimized nanocomposite balanced electric double-layer and pseudocapacitive charge storage while delivering the highest specific capacitance and best cycling stability among all investigated materials, outperforming both pristine MXene and polythiophene. A symmetric supercapacitor assembled from the nanocomposite delivered a specific capacitance of 30.48 F/g at 1 mV/s and 27.63 F/g at 5 A/g, retained 84.2% of its initial capacitance after 10,000 cycles, and achieved an energy density of 0.61 Wh/kg at a power density of 1000 W/kg. These findings present controlled oxidative polymerization as an effective strategy for integrating conducting polymers with oxidation-sensitive MXenes while preserving their structural integrity and enabling interfacial electronic coupling for improved electrochemical performance.