B₄C‐Nanowires/Carbon‐Microfiber Hybrid Structures and Composites from Cotton T‐shirts

B4C-nanowire/carbon-microfiber hybrid structures are synthesized using cotton T-shirts as both the template and carbon source. The B4C nanowires exhibit a high elastic modulus of 428.1 ± 9.3 GPa and elastic recovery after multiple high-strain bending cycles without brittle failure or obvious residual deformation for the strain up to 45%. The hybrid structures can block 99.8% UV irradiation and achieve a superior reinforcing effect in epoxy composites.