Design of nitrogen-doped carbon nanotubes/cobalt@carbon composite foam with high electromagnetic wave absorption ability

Abstract

The development of simple, efficient, and multifunctional absorbers is highly promising yet remains challenging. In this work, nitrogen-doped carbon nanotubes/cobalt@carbon (NCNTs/Co/C) composite foam was synthesized through a simple two-step procedure. This composite foam possessed a hollow skeleton structure, which was constructed by metal-catalyzed growth in situ of a large number of CNTs. Combined with structural advantages, excellent impedance matching, and multiple loss mechanisms, the ternary composite foam achieved a minimum reflection loss of −58.23 dB at 11.52 GHz (X-band) with only a 15% filling ratio (paraffin matrix) and a thickness of 2.72 mm at an optimized carbonization temperature of 700 °C, together with an effective absorption bandwidth of 4.5 GHz. Furthermore, the radar cross-section (RCS) reduction reached 37.74 dBm², and its values were wholly less than −20.0 dBm² from −90° to 90°, which indicated the strong dissipation capability of radar waves. Therefore, such a convenient strategy and low cost could offer commercial guidance to design carbon-based composites as electromagnetic wave (EMW) absorbing material.