NiCo Alloy/Carbon Nanorods Decorated with Carbon Nanotubes for Microwave Absorption

Abstract

Fabricating high-performance electromagnetic absorbents with strong absorbing intensity and wide effective absorbing bandwidth at low filler loading is still a challenge. Herein, hierarchical NiCo alloy/carbon nanorod@carbon nanotube (NiCo alloy/carbon nanorod@CNT) structures were prepared by a carbonization process using NiCo-MOF-74 nanorods as precursors in Ar flow, in which the aspect ratio of the NiCo alloy/carbon nanorod and the coating density of the CNTs could be easily controlled by the ratio of Ni/Co in the precursor. When the Ni/Co molar ratio was 1:1, a dual electric network was easily formed among the NiCo alloy/carbon nanorods as well as between the intertwined coating CNTs due to the higher aspect ratio and larger coating density, which induced significant enhancement of the comprehensive microwave absorbing properties of the NiCo alloy/carbon nanorod@CNT composites. By adding only 5 wt % to paraffin, the resulting composite displayed a maximum reflection loss of −58.8 dB and a covered an effective bandwidth as wide as 6.5 GHz (11.5–18 GHz) with a matching thickness of 2.6 mm. These outstanding microwave absorption properties can be ascribed to the stronger microwave attenuation capacity caused by the dual electric network for extra conduction loss and better impedance matching. This work provides a new direction for the design of carbon-based absorber with high performance at low filler loading.