Synergistic advancements in MXene-ZnO interfacial engineering for triboelectric nanogenerators and pulsed-power supercapacitors

Abstract

The advent of self-powered supercapacitors signs a transformative increase in energy storage, seamlessly integrating triboelectric nanogenerators (TENGs) for self-governing energy harvesting. Two-dimensional MXenes, celebrated for their superior electrical conductivity and tunable surface chemistry, emerge as compelling candidates for supercapacitor electrodes and triboelectric layers. However, intrinsic restacking tendencies hinder ion diffusion and limit charge storage capabilities. To overcome this constraint, a sonication-assisted hybridization of MXene with morphologically distinct ZnO nanostructures (nanoparticles (ZNP), nanorods (ZNR), and nanoflowers (ZNF)) was meticulously engineered. Density of States (DOS) analysis elucidates a profound enhancement in electronic conductivity and active surface sites, corroborated by effective potential calculations that confirm improved charge transport dynamics. A PVDF_MXene_ZnO nanofiber-based TENG, incorporating 15 wt% ZNF, yielded an astounding peak voltage of 1010 V and a power density of 355.59 μW/cm² under a mechanical force of 40 N at 8 Hz. Electrochemical evaluations in 1 M K₂SO₄ electrolyte revealed that MXene_ZnO (5 wt% ZNF) electrodes achieved an exceptional capacitance of 340 F/g at 3 A/g, retaining 86.86 % stability over 10,000 cycles. A symmetric supercapacitor demonstrated an energy density of 4.79 Wh/kg and a power density of 972 W/kg, efficiently powering LEDs and real-time traffic signals. These findings solidify MXene-ZnO as a frontier material, advancing the scope of self-powered energy storage for next-generation sustainable electronics and intelligent power grids.