In situ carbon nanotubes encapsulated metal Nickel as high-performance microwave absorber from Ni-Zn Metal-Organic framework derivative

In this study, a facile metal-organic framework (MOF) derived strategy was rationally designed in situ carbon nanotubes encapsulated metal nickel from Ni-Zn- MOFs. Hierarchical ZnO-Ni@C materials consist of nanorods-composed shell and a microsphere yolk. Most of the nickel metal wrapped by the graphitized carbon layers or encapsulated at the top of the carbon nanotubes. Meanwhile, the ZnO nanoparticles randomly distribute in this yolk-shell structure. It is worth mentioning that the pyrolysis temperature plays a crucial factor in the formation process of porous ZnO-Ni@C composites with semiconductor, magnetic metal nanoparticles and carbon matrix. In order to explore the microwave absorption properties, associated chemical properties, morphology and electromagnetic parameters of the ZnO-Ni@C materials are discussed in detail. With the high surface area, special yolk-shell structure, outstanding electron transportability and the combined magnetic and dielectric loss, the optimized ZnO-Ni@CNT exhibits excellent polarization loss ability, strong microwave energy dissipation, and wide absorption band. The optimal microwave absorption property in ZnO-Ni@CNT reaches a minimum reflection loss (RL) value of -58.6 dB at 2.3 mm, and effective absorption frequency range (RL <= -10 dB) of 4.8 GHz. Those results show that the polarization relaxation, the conductive network, multiple reflection, and special interface structure favor to the microwave absorption performance. (C) 2019 Elsevier B.V. All rights reserved.