A Self‐foaming Strategy to Construct Small Mo2C Nanoparticles Decorated 3D Carbon Foams as Superior Electromagnetic Wave Absorbing Materials with Strong Corrosion Resistance.

3D macroporous carbon‐based foams are always considered as promising candidates for high‐performance electromagnetic (EM) wave absorbing materials due to the collaborative EM contribution and salutary structure effect. However, the uneven distribution of heterogeneous EM components and the cumbersome preparation process have become key issues to hinder their performance improvement and practical popularity. Herein, the fabrication of 3D carbon foam decorated with small and highly dispersed Mo2C nanoparticles is realized by an innovative self‐foaming strategy. The foaming mechanism can be attributed to the decomposition of nitrate during the softening process of organic polymers. The good dispersion of Mo2C nanoparticles boosts interfacial polarization significantly. After regulating the content of Mo2C nanoparticles, the optimal Mo2C/CF‐<italic>x</italic> exhibits good EM absorption performance, whose minimum reflection loss intensity value can reach up to ‐72.2 dB, and effective absorption bandwidth covers 6.7 GHz with a thickness of 2.30 mm. Very importantly, the resultant Mo2C/CF‐<italic>x</italic> exhibits hydrophobicity and strong acidic anticorrosion, and a long‐time treatment in HCl solution (6.0 mol L−1) produces negligible impacts on their EM functions. It is believed that this extraordinary feature may render Mo2C/C foams as qualified and durable EM wave absorbing materials (EWAMs) under rigorous conditions. [ABSTRACT FROM AUTHOR]