Preparation Of Reduced Graphene Oxide/carbon Nanotube/iron-based Magnetic Composite Material Heterojunction And Research On Its Microwave Absorbing Properties

With the rapid development of the times,microwave absorbing materials play an increasingly important role in the fields of aviation stealth technology,environmental protection,communication facilities and so on.Therefore,high performance microwave absorbing materials with light weight,strong absorption ability,wide absorption frequency and high stability have attracted wide attention.In addition,in recent years,van der Waals heterojunctions,as a new and unique structure,have excellent electrochemical performance,but also have good interfacial effects and synergistic effects,which has become the focus of research in this field.According to the electromagnetic wave conversion law,the composite of dielectric loss and magnetic loss is expected to produce high performance absorbing materials.In this paper,By introducing graphene and carbon nanotubes（CNTs）to construct and synthesize magnetic nanoparticles@CNTs-reduced graphene oxide（RGO）van der Waals heterojunction nanocomposites and graphene oxide（GO）/CNTs/Co_xFe_3-xO₄ternary nanocomposites by hydrothermal and chemical vapor deposition,respectively.And their electromagnetic and microwave absorption properties were deeply investigated.The main research contents are as follows:（1）The different categories of magnetic nanoparticles@CNTs-RGO van der Waals heterostructure composites were synthesized by two-step method.First,Fe OOH nanorods were deposited on the surface of few-layer RGO nanosheets by a hydrothermal method,then catalytic decomposition of acetylene on the Fe OOH-RGO by a chemical vapor deposition method.By controlling the decomposition time of acetylene,we can selectively synthesize heterostructure composites with different categories and carbon nanotube content composed of two-dimensional RGO nanosheets,zero-dimensional magnetic nanoparticles and one-dimensional CNTs,such as:Fe₃O₄@CNTs-RGO,Fe@Fe₃C@CNTs-RGO and Fe@Fe₂C@CNTs-RGO.In response,we systematically investigated the microstructure,physical phase,and electromagnetic wave absorption properties of heterostructure composites.The results show that magnetic nanoparticles@CNTs-RGO van der waals heterostructure composites all exhibit excellent microwave absorption properties.Furthermore,the obtained Fe@Fe₂C@CNTs-RGO samples exhibit obvious enhancement of microwave absorption properties due to the improved dielectric loss performance,attenuation constant,defects and/or multiple interfacial polarizations.（2）The GO/CNTs/Co_xFe_3-xO₄（x=0.6,0.43 and 0.375）ternary nanocomposites were carefully designed and successfully prepared by one-step hydrothermal method.GO/CNTs/Co_xFe_3-xO₄ ternary nanocomposites with different magnetic content and Co:Fe molar ratio can be selectively synthesized by regulating the addition of amount of substance iron source,which is beneficial to adjust their impedance matching and electromagnetic wave attenuation characteristics.According to the study of electromagnetic parameters and absorption properties of electromagnetic waves,GO/CNTs/Co_xFe_3-xO₄ ternary nano-complexes exhibit high performance of electromagnetic wave absorption.Moreover,GO/CNTs/Co_xFe_3-xO₄（x=0.375）samples have more significant electromagnetic wave absorption properties attributed to the good impedance matching and excellent collaboration among dielectric/magnetic loss performance and attenuation constant.