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.

中文翻译：

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碳纳米管修饰的NiCo合金/碳纳米棒用于微波吸收

在低填充量下制造具有强吸收强度和宽有效吸收带宽的高性能电磁吸收剂仍然是一个挑战。在此，以NiCo-MOF-74纳米棒为前驱体，通过碳化工艺，通过碳化工艺制备了分层的NiCo合金/碳纳米棒@碳纳米管（NiCo合金/碳纳米棒@CNT）结构。碳纳米棒和CNT的涂层密度可以通过前驱体中Ni / Co的比例轻松控制。当Ni / Co摩尔比为1：1时，由于高纵横比和较大的涂层密度，在NiCo合金/碳纳米棒之间以及缠结的涂层CNT之间容易形成双电网络，从而显着提高了NiCo合金/碳纳米棒@CNT复合材料的综合微波吸收性能。通过仅添加5 wt％的石蜡，所得复合材料的最大反射损耗为-58.8 dB，覆盖了6.5 GHz（11.5–18 GHz）的有效带宽，匹配厚度为2.6 mm。这些出色的微波吸收特性可以归因于双电网带来的更强的微波衰减能力，从而实现了额外的传导损耗和更好的阻抗匹配。这项工作为低填充量下高性能的碳基吸收剂的设计提供了新的方向。8 dB，覆盖有效带宽，最大宽度为6.5 GHz（11.5–18 GHz），匹配厚度为2.6 mm。这些出色的微波吸收特性可以归因于双电网带来的更强的微波衰减能力，从而实现了额外的传导损耗和更好的阻抗匹配。这项工作为低填充量下高性能的碳基吸收剂的设计提供了新的方向。8 dB，覆盖的有效带宽高达6.5 GHz（11.5–18 GHz），匹配厚度为2.6 mm。这些出色的微波吸收特性可以归因于双电网带来的更强的微波衰减能力，从而实现了额外的传导损耗和更好的阻抗匹配。这项工作为低填充量下高性能的碳基吸收剂的设计提供了新的方向。