Bimetallic MOF-derived CoFe@nitrogen-doped carbon composites for wide bandwidth and excellent microwave absorption.

Magnetic carbon-based composites derived from metal-organic frameworks have been regarded as potential microwave absorption (MA) materials. Here, we successfully fabricate magnetic CoFe alloy@nitrogen-doped carbon shell (CoFe@NC) composites with strong absorption, thin thickness, and wide bandwidth through the thermal decomposition of CoFe Prussian blue analogues. Annealing temperature has a remarkable influence on dielectric and magnetic behavior of composites, thereby improving the impedance matching and MA ability. When the annealing temperature of CoFe@NC composites is 600 ℃, the CoFe@NC composites show the best MA performance with the reflection loss (RL) value of − 50.77 dB and the maximum effective absorbing bandwidth (RL ≤ −10 dB) of 7.2 GHz (2.1 mm). The CoFe@NC composites possess superior MA properties because of the high dielectric loss deriving from nitrogen-doped carbon as the shell, high magnetic loss originating from CoFe alloy as the core and conduction loss. The superior MA performance of CoFe alloy@NC composites make them ideal candidates for high-efficient MA applications. • CoFe Prussian blue analogue is an ideal template for microwave absorption. • Nitrogen-doped carbon shell (NC) provides more dipole polarization. • CoFe@NC have properties of strong absorption, thin thickness and wide bandwidth. • The preparation method of CoFe@NC is very simple. [ABSTRACT FROM AUTHOR]