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.