Magnetic CoFe alloy@C nanocomposites derived from ZnCo-MOF for electromagnetic wave absorption

Abstract

Magnetic quantum dot (QD)-like CoFe alloy@C nanocomposites derived from ZnCo-MOF using low-dimensional carbon as carriers for electromagnetic wave (EMW) absorption were successfully synthesized by in situ growth and pyrolysis. The resulting CoFe@C nanocomposites were homogeneously conjoined with different carbon supports such as two-dimensional (2D) reduced graphene oxide (rGO) and one-dimensional (1D) carbon nanotubes (CNT). Results indicated EMW absorption properties of CoFe@C were enhanced by introduction of rGO and CNT as carbon hosts for the construction of conductive networks due to the excellent impedance matching and electromagnetic attenuation. The rGO-supported CoFe@C composites annealed at 900 °C (rGO-CoFe@C-900) revealed a minimum reflection loss (RLmin) of −36.08 dB at the sample thickness of 3.0 mm and an effective bandwidth (RL < −10 dB) of 5.17 GHz at 3.5 m. Moreover, the CNT-supported CoFe@C nanocomposites pyrolyzed at 900 °C (CNT-CoFe@C-900) exhibited optimum EMW absorption performances due to the continuous 3D conductive networks, RLmin of −40.00 dB with the thickness of 3.0 mm, and effective absorption bandwidth reached 5.62 GHz with a thickness of 2.0 mm. In particular, the specific reflection loss values of the resulting nanocomposites significantly preceded that of the reported similar dielectric-magnetic hybrids. In view of the superior EMW absorption properties, the as-fabricated low-dimensional carbon-supported magnetic quantum dot-like (QD-like) CoFe alloy@C composites will be utilized as ideal candidates for high-efficient EMW absorption.