“Magnetic carbon fibre” for multifunctional composites with improved recyclability

The sustainable management of carbon fiber (CF) waste has become increasingly imperative due to the rising demand for carbon fiber-reinforced composites across diverse industries. Conventional recycling methods, such as pyrolysis, face significant challenges, including the complex and costly separation of composite constituents and the difficulty of realigning reclaimed CF, which is typically discontinuous. Herein, we introduce a scalable strategy for imparting magnetic functionality to carbon fibers, facilitating their efficient reclamation and reuse. Our approach involves the initial surface functionalization of CF, followed by electrochemical deposition of covalently bound iron oxide coatings, thereby imbuing CF with magnetic properties. When incorporated into composite structures, these modified fibers exhibit (1) a 34 % enhancement in fiber-matrix interfacial adhesion, (2) improved separation and recovery of CF post-pyrolysis, and (3) multifunctional performance, including superior energy storage capabilities (6.5 F/g at 5 mV/s) and exceptional electromagnetic interference (EMI) shielding efficacy (−52 dB), effectively attenuating ~37 % more electromagnetic waves. This novel methodology not only streamlines the recycling of CF-reinforced polymers (CFRPs) but also expands the scope of their second-life applications, paving the way for more sustainable and multifunctional composite materials. • Covalently functionalized CF with Fe 2 O 3 enables magnetism assisted recyclability. • Innovative electrochemically modified surface design enhances IFSS by 34 %. • EMI shielding of −52 dB with 37 % higher wave blocking vs pristine CF with one ply • Reclaimed magnetic CF can be used in energy storage (48.5 F/g at 0.5 A/g). • Multifunctional CF deliver recyclability, EMI shielding, and energy storage.