Heterogeneous Interface Engineering of Bi-Metal MOFs-derived ZnFe₂O₄-ZnO-Fe@C Microspheres via Confined Growth Strategy Toward Superior Electromagnetic Wave Absorption

Heterogeneous interface regulation plays an important role in tailoring the intrinsic electromagnetic (EM) properties for obtaining excellent EM wave absorption, which still faces huge challenge. In this work, bi-metal MOFs-derived ZnFe2O4-ZnO-Fe@C (ZZFC) microspheres with custom-built heterogeneous interfaces are successfully fabricated via a confined growth strategy. Bi-metal Fe-Zn-ZIF with tailored coordination structure and chemical bonding are first selected as the precursor template. After undergoing the annealing process, the metal Fe2+ host is converted into magnetic Fe nanoparticles (NPs). The Zn2+ host is transformed into semiconductor zinc oxide (ZnO) with increasing (101) crystal-oriented growth. At the same time, metal hosts Fe2+ and Zn2+ are further reacted to synthesize the zinc ferrite (ZnZnFe2O4). Formed Fe nanoparticles catalyze organic ligands to constitute graphitized carbon layers, which confine the further growth of ZnZnFe2O4, ZnO, and Fe NPs. Combined with the well impendence and synergy absorption mechanism (magnetic loss, interface polarization, and conduction loss), optimized magnetic-dielectric ZnZnFe2O4-ZnO-Fe@C microspheres exhibit outstanding EM wave absorption with the minimum reflection loss -66.5 dB at only 2.0 mm thickness. Bi-metal MOF-derived magnetic-dielectric absorption materials with tailored heterogeneous interfaces provide a new sight to design an efficient EM wave absorption system.