Functional and structural modification of polyvinyl alcohol/carbon nanotubes composite fibers

Abstract

This research was based on the synthesis of new materials with capacitive properties and low cost, seeking efficient energy storage, through the manufacture and characterization of composite materials of polyvinyl alcohol (PVA)/multiwalled carbon nanotubes with carboxyl group (MWCNTs-COOH) (1 %) for electrodes. Forcespinning and electrospinning techniques were used to develop composite fiber films and compare the physical structure of the fibers and its influence on their capacitive properties. These samples were characterized by SEM, FESEM, FT-IR, XRD, TGA, Raman spectroscopy and electrochemical techniques. The characterization of the composites makes evident the structural modification that the material underwent after the treatments. The electrochemical parameters were measured by electrochemical impedance spectroscopy (EIS), with the samples immersed in H₂SO₄ 1 M as electrolyte. The PVA/MWCNTs-COOH composites with thermal treatment (340 °C) showed a considerable decrease in total impedance of up to 6 orders of magnitude (124 Ω) with respect to the blank sample (2.3 × 10⁸ Ω), as a function of the immersion time in the acid solution. As well as, an increase in the specific capacitance of up to 8 orders of magnitude (1.01×10⁻² F cm⁻²) with respect to the blank sample (5.07 × 10⁻¹⁰ F cm⁻²) for the composite manufactured by the electrospinning technique. The obtaining of fibers with directionality as a result of the forcespinning technique, the highly crossed network observed by electrospinning and the electrochemical properties shown by the structural modification of PVA/MWCNTs-COOH composite, make it, a material with potential technological applications such as electrode in electrochemical capacitors.