A novel cellulose-derived graphite carbon/ZnO composite by atomic layer deposition as over-wideband microwave absorbents

Abstract

It is a major challenge to obtain broadband microwave absorption (MA) properties using low dielectric or magnetic nanoparticles decorated- carbon composites due to the limited single conductive loss or polarization loss of the carbon materials used as substrates. The novel pure cellulose-derived graphite carbon materials (CGC) can be used as an exceptional substrate option due to its special defective graphitic carbon structure with conduction and polarization loss. Herein, the CGC@ZnO composites were first synthesized by atomic layer deposition (ALD) for microwave absorbents. Thanks to the multiple interfaces composed of graphitic carbon, defective carbon, and polar ZnO molecules, the CGC@ZnO composites exhibit superior MA properties. Specifically, the CZ-3 achieves a minimum reflection loss (RLmin) of -50.5 dB (over 99.999% MA) at 6.16 GHz in 2.98 mm. Amazingly, the maximum effective absorption bandwidth (RL < 10 dB, EABmax) can be up to 6.48 GHz only at 1.59 mm. Besides, the frequency range of EAB even extends to 12.7 GHz when the thickness is varied in the range of 1.0-3.0 mm. The ultra-broadband absorption property is mainly attributed to its strong electromagnetic attenuation capability and excellent impedance matching, making it one of the most promising materials for MA applications.