Melamine-induced formation of carbon nanotubes assembly on metal-organic framework-derived Co/C composites for lightweight and broadband microwave absorption

Extending effective absorption bandwidth at a low filling ratio is still a challenge for metal-organic framework-derived microwave absorbing materials. Herein, varied complex structures based on CNTs have been built on Co/C particles derived from ZIF-67 via melamine-involved annealing routes. It was found that cobalt nanoparticles derived from ZIF-67 act as catalysts for the growth of CNTs, effectively promoting and controlling the content of melamine. Due to the effective control of the CNT-containing complex structure, excellent microwave absorption performance was achieved at a rather low filling ratio of 20 wt%, which can be attributed to improved attenuation ability and ameliorated impedance matching. Results show that highly graphitic CNTs benefit the formation of the electron transport network and enhancement of conduction loss. Unique one-dimensional complex structure and abundant Co/C interfaces strengthen the polarization loss. When the dielectric loss was optimized at different frequencies, appropriate impedance matching was also gained to realize a broad effective absorption bandwidth of 5.6 and 4.4 GHz in Ku and X bands, respectively. This work may provide novel insights into the synthesis and design of CNT-containing metal-organic framework-derived materials with lightweight features and wide frequency response.

Automated summary

In this study, excellent microwave absorption performance was achieved at a low filling ratio of 20 wt% using Co/C particles derived from ZIF-67 and a melamine-involved annealing route. The highly graphitic CNTs benefited the formation of an electron transport network and enhanced conduction loss, while the unique one-dimensional complex structure and abundant Co/C interfaces strengthened the polarization loss. Through optimizing dielectric loss and impedance matching at different frequencies, a broad effective absorption bandwidth in Ku and X bands was realized, showcasing the potential for novel lightweight materials with wide frequency response.