Defect-Engineered Nitride-based MXene/rGO Nanohybrids: A Unified Strategy for High-Performance Energy Storage and Corrosion-Resistant Electrodes

Abstract

Two-dimensional MXenes have emerged as transformative materials for high-performance energy storage and corrosion-resistant applications; however, challenges such as restacking, surface instability, and limited electroactive sites restrict their practical deployment. In this invited talk, a comprehensive study on Ti$_2$NT$_x$/rGO and V$_2$NT$_x$/rGO nanocomposites synthesized through controlled chemical etching and reduction routes is presented. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirm the formation of multilayered architectures, expanded interlayer spacing, and Ti$_2$NT$_x$/rGO quantum dots arising from quantum confinement. The integration of reduced graphene oxide (rGO) effectively modulates the optical band gaps (Ti$_2$NT$_x$: 5.59$\rightarrow$4.53~eV; V$_2$NT$_x$: 4.75--5.11~eV), suppresses oxidation, and enhances accessible surface area and porosity. Electrochemical measurements reveal markedly improved charge-storage behaviour, with Ti$_2$NT$_x$/rGO achieving a specific capacitance of up to 1203.86 F g$^{-1}$ (galvanostatic charge--discharge), while V$_2$NT$_x$/rGO delivers 622.97 F g$^{-1}$ along with outstanding cycling stability (88.3% retention after 10,000 cycles). The optimized composites further exhibit reduced charge-transfer resistance ($R_{\mathrm{CT}} = 7.23~\Omega$) and excellent corrosion resistance, with corrosion rates as low as $1.5\times10^{-8}$~mm~y$^{-1}$. These results underscore the synergistic role of rGO in enhancing electron transport and interfacial stability. Overall, the findings establish nitride-based MXene/rGO nanohybrids as versatile, defect-engineered, and scalable materials for next-generation supercapacitors and protective coatings, effectively bridging fundamental insights with technological relevance.