N-doped residual carbon from coal gasification fine slag decorated with Fe_(3)O_(4)nanoparticles for electromagnetic wave absorption

The electromagnetic wave absorption(EMWA)performance of materials is affected by their dielectric and magnetic properties.Here,ferroferric oxide@N-doped residual carbon(Fe_(3)O_(4)@NRC)composites were successfully fabricated by decorating NRC with Fe_(3)O_(4)nanoparticles via a facile chemical co-precipitation method.The RC was obtained through acid treatment to remove the inorganic minerals in coal gasification fine slag.The structure,composition,thermal stability,morphology,and related EM parameters of the as-fabricated Fe_(3)O_(4)@NRC composites were thoroughly tested via analytical techniques.Notably,both the Fe_(3)O_(4)@NRC-2 and Fe_(3)O_(4)@NRC-3 composites exhibited superior EMWA capacity.When 40%mass was added,the value of minimal reflection loss(RL_(min))for Fe_(3)O_(4)@NRC-2 was-37.4 dB,and the effective absorption bandwidth(EAB,RL≤-10 dB)reached 4.16 GHz(13.84-18.00 GHz)at a thickness of 1.5 mm.Besides,the value of impedance matching was 1.00 as the RL_(min)was achieved.The results demonstrated that the EMWA performance of the composites could be adjusted by controlling the content of Fe_(3)O_(4)nanoparticles.The magnetic/carbon composites exhibited superior EMWA performance,thus promoting the resource utilization of residual carbon in coal gasification fine slag from coal gasification.