1D graphene nanoribbons-mediated defect engineering in 2D MXene for high-performance supercapacitors

Carbon-based supercapacitors have been extensively explored by the virtue of their exceptional performance in terms of charge-storage capacity, electrical conductivity, and good stability. However, the rush to find potential approaches for increasing their specific capacitance and specific energy without adversely affecting the specific power is still exciting. Herein, we synthesized hierarchically structured carbon-based composites based on 2D MXene sheets with an interconnected conductive porous network of 1D graphene nanoribbons (GNRs). Synergistic effects arising due to the defect engineering of 2D MXene sheets with 1D GNRs led to high surface-area, effective ion-transport, and improved structural robustness of the composite electrodes, thereby enhancing the specific capacitance along with specific energy of device while preserving its specific power. The electrochemical studies revealed that the composites with 1 wt.% GNRs (GMX-B) outperformed when the composition of GNRs was varied from 0.5 to 1.5 wt. % in MXene (GMX-A, GMX-B, and GMX-C). In comparison to pristine MXene and pristine GNRs, GMX-B exhibited ∼2.54 and ∼2.74 folded higher capacitance of 238.96 F/g at 0.6 A/g current density, respectively, a higher capacitance retention of 72.16% for a scan rate from 10–140 mV/s as well as a good cyclic stability of 85.11% over 10 000 charge/discharge cycles. Furthermore, GMX-B electrode achieved a high specific energy of 4.066 Wh/Kg while maintaining a specific power of 210.640 W/Kg as compared to pristine MXene (1.597 Wh/Kg at 211.989 W/Kg) and pristine GNRs (1.482 Wh/Kg at 211.089 W/Kg). Thus, we anticipated that the use of hierarchically engineered 1D/2D carbon-based composites with considerable improvement in its interfacial properties holds great potential to achieve high-performing energy-storage devices.