Multi-dimensional ZnO@MWCNTs assembly derived from MOF-5 heterojunction as highly efficient microwave absorber

Metal-organic framework (MOF) derivatives have been arousing great attention in microwave absorption (MA) applications because of the adaptable morphological and component variance. However, it is still a huge challenge to construct multi-dimensional assembly with special heterostructure based on MOF and conductive carbon materials for excellent MA performance. Here, we successfully synthesized the cube-like assembly of multi-walled carbon nanotubes (MWCNTs) and ZnO ([email protected]) with unique multi-dimensional architecture via controlling the pyrolysis time of MOF-5 wrapped by MWCNTs. The [email protected] are composed of zero-dimensional ZnO nanoparticles, one-dimensional MWCNTs, and three-dimensional micro-scale porous carbon framework. These various dimensional components confined within the cube space lead to the strong reflection loss (RL) at different frequencies, thus resulting in exceptional MA performance. The [email protected] can reach a RL peak of −34.4 dB at only 1.5 mm thickness. More importantly, the maximum RL can achieve −47.4 dB at 2.7 mm with a mass loading as low as 20%. The optimized MA performance can be ascribed to high-density polarized sites, tightly interwoven MWCNTs conductive network, and strong multiple scattering that all induced by the multi-dimensional structures and components. Therefore, novel [email protected] composites are promising as a lightweight and highly efficient microwave absorber.