Hollow Gradient-Structured Iron-Anchored Carbon Nanospheres for Enhanced Electromagnetic Wave Absorption

The electromagnetic contamination caused by the extensive use of communication equipment has become one of the greatest endangers to human beings, creating a sharp requirement for electromagnetic-absorbing (EMA) material with excellent performances 1 . Carbon-based materials (CBMs), such as carbon fibers 2 , carbon nanotubes 3 , carbon nanosphere 4 as well as graphene 5 , are considered ideal candidates for EMA because of their excellent traits of lightweight, corrosion resistance and excellent dielectric attenuation. Nevertheless, the EMA properties of single CBM absorbers are severely affected by unsatisfied impedance and inferior broad-frequency absorption ability 6 , 7 . Generally, two typical strategies, such as integrating carbon with magnetic materials and structure design 8 , are applied to settle these dilemmas. For improved impedance matching and highly adjustable polarization, exploiting multicomponent tactics has proven to be one of the most effective ways 9 . However, simply assembling magnetic components (MCs) with CBM cause the aggregation phenomenon, resulting in magnetic attenuation and oxidative deterioration 10 . Thus, many recent works were conducted to find out the relationship between microstructural design and EMA performance, due to structure-induced physical effects 11 , 12 . For example, structures of single atoms 13 , heterointerface 14 , phase engineering 15 , hollow spheres 16 , cellular structure 17 and nanofiber 18 are proved to be helpful in improving EMA ability. However, exploiting an effective method to integrate all the merits of prominent impedance matching, lightweight, chemical resistance, and anti-agglomeration in a single structure is still challenging.