Nitrogen-doped graphene layers encapsulated NiFe bimetallic nanoparticles synthesized by arc discharge method for high-efficient microwave absorber
Development of inexpensive yet high-performance microwave absorbers to attenuate electromagnetic pollution stemming from the wide applications of various electrical devices is of great significance. Magnetic NiFe alloys with relatively high permeability and multiply magnetic resonances are advantageous to broaden absorption bandwidth. Benefiting from the coatings of carbon materials, the NiFe@C composites can efficiently elevate the whole capabilities of oxidation/corrosion resistance. Meanwhile, the formation of numerous hetero interfaces between C and NiFe alloys leads to interfacial polarization. However, their relatively strong dielectric loss are still difficult to couple magnetic loss, resulting in the impedance mismatching. In this work, NiFe alloy nanoparticles embedded in nitrogen-doped graphene layers are successfully fabricated under a mixed gas of CH4/N2/Ar. By controlling the number of graphene layers and nitrogen doping level, the overall impedance can be effectively ameliorated. Experimental results indicate that the minimum reflection loss (R) can reach -46.89 dB at 11.96 GHz, and accompanying an effective absorption bandwidth of more than 4.1 GHz. Our work will advance the study of magnetic alloys/N-doped graphene composites for microwave absorption.