Nanostructured carbon‐filled carbon fibre reinforced polymer composites: Properties, fabrication methods, applications, and future prospects: A review

Abstract The persistent demand for high‐performance, lightweight, and multifunctional materials has positioned carbon fibre‐reinforced polymer composites (CFRPCs) at the forefront of innovation across critical sectors, including aerospace, defence, civil engineering, and energy. This review provides a critical examination of how various micro‐ and nanostructured carbonaceous fillers—specifically, carbon nanofibres, carbon nanotubes (CNTs), graphene, graphite flakes, nano‐diamonds, and human hair‐derived porous carbon—are fundamentally altering the mechanical, viscoelastic, and electrical characteristics of CFRPCs. The present study reveals that these fillers, which span one‐dimensional (1D), two‐dimensional (2D), and three‐dimensional (3D) architectures, allow for highly tailored reinforcement and establish electrical percolation thresholds at remarkably low loadings. Notably, CNT‐reinforced composites have demonstrated substantial gains, achieving flexural strengths up to 580 MPa. Furthermore, this study explores the significant synergistic effects in hybrid filler systems, which consistently yield superior stiffness, damping capacity, and conductivity compared to their single‐filler counterparts, applications, challenges, and future directions. The paper also provides a comparative analysis of advanced fabrication techniques such as vacuum‐assisted resin transfer moulding, compression moulding, and 3D printing, highlighting their direct influence on scalability, fibre wet‐out quality, and overall structural integrity. Despite these clear advances, persistent challenges remain in achieving uniform filler dispersion, cost‐effective processing, and material recyclability.