Enhanced wideband microwave absorption of hollow carbon nanowires derived from a template of Al4C3@C nanowires

The hollow carbon nanowires with large number of surface defects and specific surface have been prepared by de-alloying Al4C3@C nanowires. Compared to the graphene-based or carbon-nanotube-based electromagnetic wave-absorbing composites reported previously, the hollow carbon nanowires achieve enhanced wideband microwave absorption due to enhanced impedance match and increased electric dipoles, which are related to the defects on the surface of the distinctive hollow structure. As a result, the complex dielectric and microwave absorption properties of the hollow carbon nanowires are significantly optimized in 2–18 GHz range. The composites filled with 50 wt% of hollow carbon nanowires in paraffin show a minimum reflection loss (RL) of −47.1 dB at 15.7 GHz with a thickness of 1.9 mm and 5.5 GHz (RL  <  −10 dB) absorbing bandwidth with thickness of 2 mm, being one of the most competitive carbon-based absorbers. This study provides an effective way to improve the microwave performance of the hollow carbon nanowires by template method.