Electrospinning and in-situ hierarchical thermal treatment to tailor C–NiCo₂O₄ nanofibers for tunable microwave absorption

The development of high-efficiency microwave absorbing materials in different frequency bands is expected to satisfy the requirement of real-time communication and national defense especially active camouflage in the information era. Herein, a carbon modified nickel cobalt oxide, C–NiCo₂O₄, porous nanofiber is successfully constructed by electrospinning and in-situ hierarchical thermal treatment engineering. The thermal treatment temperature enables tailoring of the C content of C–NiCo₂O₄ so as to modulate the conduction loss. More importantly, the absorption frequency can be tuned from K_u to X and even to C band due to that the proper tailoring affords varying synergy effect of dielectric and magnetic properties on impedance matching degree of each C–NiCo₂O₄ composite. Since low reflection loss suggests efficient energy conversion and heat generation, the high electromagnetic absorption makes the material extremely potential for application in multifunctional nano-micro electromagnetic devices.