Dependence of reduction degree on electromagnetic absorption of graphene nanoribbon unzipped from carbon nanotube.

Carbon materials are very promising for electromagnetic wave absorption application due to their light weight and low cost, where the reflection loss is used to evaluate the absorption efficiency. However, the reflection loss of carbon materials (carbon foam, graphene, and carbon nanotube) without loading magnetic particles is not as high as expected. Here, we propose to unzip carbon nanotubes into graphene oxide nanoribbons (GONRs), followed by controllable reduction treatment using hydrazine hydrate, and the reduced GONRs were finalized (called as r-GONRs). The r-GONRs exhibit obvious dielectric relaxation behaviors compared to GONRs, and the dielectric loss is improved by increasing the reduction degree. The optimized r-GONRs show ultrahigh electromagnetic absorption, up to -65.09 dB at a thickness of 2 mm, which is more advantageous than the reported values of other carbon materials. The efficient absorption bandwidth (reflection loss ≤-10 dB) reaches 7.06 GHz. These are attributed to the large dielectric loss of the unique graphene nanoribbon. Our controllable reduced graphene nanoribbon is promising in the application of radar wave absorption and electromagnetic shielding.