MOF-on-MOF-derived GC/Co@CNTs with multiscale heterostructures for enhanced microwave absorption

Metal-organic framework (MOF)-derived electromagnetic wave absorbing materials have attracted considerable interest because of their tunable composition, rich porosity, and structural versatility. However, conventional single-MOF-derived materials often have limited metallic components and structures with a single dimensionality, which hinder the simultaneous optimization of electromagnetic wave absorption performance. In this work, a ZIF-L@ZIF-67 precursor with a MOF-on-MOF architecture was designed. Through high-temperature pyrolysis, it was converted into graphitized carbon/Co nanoparticles@carbon nanotubes (GC/Co@CNTs) composites composed of two-dimensional graphitized carbon, one-dimensional carbon nanotubes, and zero-dimensional Co nanoparticles. By tuning the pyrolysis temperature, the magnetodielectric response response of the materials was effectively regulated. The optimized GC/Co@CNTs-800 exhibited a minimum reflection loss (RL_min) of −69.4 dB at 1.85 mm and an effective absorption bandwidth (EAB) of 6.04 GHz at 2.00 mm. During pyrolysis, the in-situ formation of a conductive carbon network, magnetic Co nanoparticles, and abundant heterogeneous interfaces synergistically promoted conduction loss, magnetic loss, and interfacial polarization. As a result, the electromagnetic attenuation capability of the composites was significantly improved. This study highlights the considerable promise of MOF-on-MOF-derived architectures for electromagnetic wave absorption and offers a viable structural engineering strategy for the development of next-generation microwave absorbers.