Bio‑Derived Hierarchical Multicore-Shell Fe2N‑Nanoparticle‑Impregnated N‑Doped Carbon Nanofiber Bundles: A Host Material for Lithium‑/Potassium‑Ion Storage

A viable bio-derived material engineering strategy is developed based on the use of skin collagen fibers for the crafting of metal-nitride–carbon nanofiber composites. N-doped carbon nanofiber bundles embedded with Fe2N nanoparticles are fabricated using a structural replication process. The composite with a hierarchically ordered, compact, and multicore–shell heterostructure exhibits increased lithium- and potassium-ion storage performances.