Highly Cuboid-Shaped Heterobimetallic Metal–Organic Frameworks Derived from Porous Co/ZnO/C Microrods with Improved Electromagnetic Wave Absorption Capabilities

Metal-organic framework (MOF)-derived porous metal/C composites have drawn considerable attention from the microwave absorption field owing to their large pore volumes and surface areas. Exploring single-MOF-derived materials with high intensity and broadband absorption is largely needed but remains a challenge. Here, porous Co/ZnO/C (CZC) microrods were fabricated easily from cuboid-shaped heterobimetallic MOFs. CZC provides an efficient platform for integrating different semiconductors (ZnO), magnetic metal (Co), and carbon sources into one particle, which enhances the electromagnetic (EM) wave-absorbing ability. The carbonization temperature which is critical for EM parameters was studied in detail. CZC annealed at 700 °C outperformed those obtained at 600 or 800 °C in terms of microwave wave-absorbing properties. The reflection loss (RL) was optimized to -52.6 (or -20.6) dB at 12.1 (or 14.8) GHz with an effective bandwidth (RL ≤ -10 dB) of 4.9 (or 5.8) GHz at the coating thickness of 3.0 (or 2.5) mm. Such enhancement of EM wave-absorbing capabilities is ascribed to the well-built porous structure, dielectric loss, and magnetic loss. This work offers a new way to prepare porous magnetic metal/C composites with excellent microwave-absorbing properties starting from heterobimetallic MOFs.