Ultrasound-Driven Fibrous MXene and Graphene Formation via Molecular Interactions for Asymmetric Supercapacitors with Enhanced Charge Storage

Abstract

Asymmetric supercapacitors (ASCs) based on 2D nanomaterials hold great promise for high-performance energy storage, yet challenges remain in ion transport and self-discharge. This work presents a facile and scalable ultrasound-driven strategy, utilizing ascorbic acid (AA), to fabricate fibrous architectures of Ti₃CNT_x MXene and reduced graphene oxide (rGO) for ASC electrodes. Molecular interactions, induced by AA and sonication, facilitate the self-assembly of nanosheets into interconnected fibrous networks with large pores, enhancing ion diffusion. Crucially, AA surface engineering reduces surface hydroxyl groups on MXene, increasing its potential of zero charge (PZC) and effectively suppressing self-discharge. The resulting Ti₃CNT_x-1.5AA-20//rGO-2.0AA-30 ASC exhibits significantly enhanced charge storage, achieving a high capacitance and excellent rate capability. Remarkably, it demonstrates a low self-discharge rate (15.53% voltage drop after 5000 s), attributed to the mitigated diffusion and Faradaic processes. This strategy proves versatile across various aqueous electrolytes (H₂SO₄, LiCl, KOH) and yields ASCs with excellent cycling stability and a high energy density of 19.7 mWh g^-1. This approach offers a promising route for next-generation supercapacitors with improved energy storage and charge retention.