# Linear Actuation of Dielectrophoretic Formed Multi-Walled Carbon Nanotube Fiber with Carbide-Derived Carbon in Polar Aprotic and Polar Protic Solvents

## TL;DR

This study shows that adding carbide-derived carbon to carbon nanotube fibers improves their actuation and energy storage performance in different solvents.

## Contribution

The novel contribution is the enhanced linear actuation and energy storage in CNT fibers with CDC in polar solvents.

## Key findings

- CNTCDC fibers showed better expansion and stress in polar aprotic and protic solvents compared to pristine CNT fibers.
- CNTCDC fibers achieved a high specific capacitance of 223 ± 17 F g−1 in aqueous media with good capacity retention.
- SEM, EDX, and Raman confirmed the structural and compositional properties of the CNTCDC fibers.

## Abstract

Carbon nanotube (CNT) fiber research focuses on developing functional fabrics with dual or multifunctional capabilities. This study investigates CNT fibers fabricated via dielectrophoresis (DEP) with the incorporation of 10 wt.% carbide-derived carbon (CDC), referred to as CNTCDC fibers. The linear actuation behavior of the CNT and the CNTCDC fibers is compared using identical electrolyte concentrations in both a polar aprotic solvent (propylene carbonate, PC) and a polar protic solvent (aqueous solution, aq). Electromechanical deformation (EMD) is studied through cyclic voltammetry and chronoamperometry. The CNTCDC fiber outperformed the pristine CNT fiber, exhibiting primary expansion during discharge in PC (stress: 1.64 kPa, strain: 0.1%) and during charge in water (stress: 1.32 kPa, strain: 0.047%). By contrast, the pristine CNT fibers showed mixed actuation responses in both solvents, resulting in diminished net stress and strain. Chronopotentiometric measurements indicated that the CNTCDC fibers achieved their highest specific capacitance in aqueous media, reaching 223 ± 17 F g−1 at ±0.8 A g−1, with a capacity retention of 94.2% at ±32 A g−1. Fundamental characterization techniques, including scanning electron microcopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and Raman spectroscopy, are employed to analyze fiber morphology and composition. The dual functionality of CNTCDC fibers, as both actuators and energy storage elements, is demonstrated.