MOF‐Fe@C Nanocomposites for Microwave Absorption

The arrival of the 5 G era has brought great benefits to our lives, but it has also brought problems such as electromagnetic radiation. Therefore, the demand for lightweight, high‐performance microwave absorbing materials with wide effective bandwidth is increasing. Herein, MIL‐53/g‐C3N4 is first synthesized from precursors of ferric chloride, terephthalic acid, and g‐C3N4, and then thermally annealed at different temperatures to generate MOF‐Fe@C nanocomposites. Heat treatment can effectively carbonize g‐C3N4 to amorphous carbon and reduce iron in MIL‐53 to magnetic Fe and Fe3O4 nanoparticles through carbon‐thermal reduction reaction. The synergistic effect of dielectric loss of amorphous carbon and magnetic losses of magnetic particles enhances attenuation and improves impedance matching, enhancing microwave absorption. The RLmin of MOF‐Fe@C(4)‐700 is as low as ‐72.78 dB at 9.44 GHz at a thickness of 3.18 mm and its effective absorption bandwidth is as broad as 4.88 GHz, covering most of X‐band frequency range. The research introduces a novel technique for synthesizing absorbers with controllable electromagnetic characteristics by incorporating g‐C3N4 as carbon sources into MOF materials.