Topological MOFs deformation for the direct preparation of electromagnetic functionalized Ni/C aerogels with good hydrophobicity and thermal insulation

Magnetic carbon-based aerogels are nowadays a kind of emerging candidates for high-performance electromagnetic wave absorbing materials (EWAMs), because their unique structural advantages lay a good foundation for the propagation and attenuation of electromagnetic (EM) wave. However, traditional post-treatment methods for magnetic carbon-based aerogels often face difficulties in maintaining aerogel structure, regulating the content of magnetic components, and dispersing magnetic particles. Herein, we first induce a topological deformation of bulky Ni-MOF particles to generate Ni-MOF aerogel assembled by crosslinked fibers, and then convert this intermediate aerogel to final Ni/C composite aerogels (NCCAs) through controllable high-temperature pyrolysis. This novel strategy achieves high loading and uniform dispersion of magnetic metal nanoparticles throughout carbon skeleton. Pyrolysis temperature plays a very important role to determine the overall attenuation capability and impedance matching of NCCAs, because it has a remarkable impact on the dielectric loss of carbon skeleton but negligible effect on magnetic loss. When the temperature is 700 °C, the optimum product (NCCA-2) will show the best EM absorption performance among this series of composites, including strong reflection loss and broad effective absorption bandwidth. Surprisingly, the integrated advantages of aerogel structure and MOFs transformation not only render NCCA-2 as a highly competitive candidate for high-performance EWAMs as compared with various Ni/C composites, but also bestow it on excellent hydrophobic and thermal insulation properties.