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

•rGO- or CNT-CoFe alloy@C nanocomposites was assembled via a host-guest strategy.•Magnetic quantum dot-like CoFe alloy embedded in C matrix derived from ZnCo-MOF.•rGO or CNT served as supports for enhanced dielectric loss and impedance matching.•The unique nanoarchitectures exhibited high-efficient EMW absorption performances.•Minimum reflection loss for CNT-CoFe@C was −40.00 dB with 3.0 mm in thickness.