Fabrication of Rod-Like Porous Co@Graphene/CNT Composites for Superior Wideband Electromagnetic Wave Absorption

Abstract

The proliferation of electronic devices has significantly in-creased electromagnetic radiation pollution, impacting human health and national defence. This instigates an urgent demand for high-performance electromagnetic wave absorbing (EWA) materials. However, designing and fabricating wideband EWA materials is highly challenging due to the dominant single loss mechanism. Herein, we designed and synthesized rod-like porous carbon composites (Co@G/CNT) by thermal cleavage of Co/Zn-ZIF bimetal-organic framework precursors, which in situ forms a compo-site of magnetic metal nano-particles, graphene, and car-bon nanotubes (CNT), leveraging both magnetic loss and dielectric loss. By increasing the Zn content in Co/Zn-ZIF precursors, the porosity of the generated Co@G/CNT was enhanced due to the Zn sub-limation. Three carbon com-posites (Co@G/CNT-1, Co@G/CNT-2, and Co@G/CNT-3) was synthesized by varying the Zn/Co ratios to be 3:1, 1:1, and 1:3, respectively. Amongst them, Co@G/CNT-3 achieved a remarkable ab-sorption bandwidth of 9.6 GHz (8.4–18.0 GHz) at 3.2 mm thickness and a minimum reflection loss of –40.36 dB at 13.5 GHz with 3.0 mm thickness. This superior perfor-mance is primarily caused by the synergistic effect arising from the composite’s hetero-geneous interfaces and its high porosity. These features enhance polarization and dielectric loss, while also facilitating multiple reflec-tions and scattering of elec-tromagnetic waves. These findings offer a valuable in-sight for the development of microwave absorbers for high-performing wideband elec-tromagnetic wave absorption.