| Three-dimensional graphene assembly—graphene aerogel was a new form of three-dimens iona graphene material with high porosity,low density,excellent dielectric properties and chemical stability,which had attracted much attention in the electromagnetic shielding field.One-dimensional magnetic ultralong Fe3O4 nanowires(Fe3O4NWs)with typical shape anisotropy had many excellent properties such as large specific surface area,space constraints and assembleability,which made it a hot spot in the microwave absorption field.The structural design of graphene aerogel and ultralong Fe3O4NWs obtained the multi-interface heterostructure was one of the feasible scientific ways to simultaneously adjust the electromagnetic shielding and microwave absorption performance.In this paper,Fe3O4 NWs-GO aerogel composite having interpenetrating microstructure with multiple electromagnetic wave loss functions was prepared by using hydrothermal method based on graphene and graphene aerogel as the carrier.And systematically studied its morphology,structure and microwave absorption and electromagnetic shielding performance.The main research contents include as follow:1.Ultralong Fe3O4NWs with uniform dispersion were synthesized by using polyethylene glycol(PEG)as the template based on hydrothermal method and further the zero-dimensional ultralong Fe3O4 NWs-GO hybrid particles with interpenetrating microstructure were also obtained.Through the self-assembly of graphene,the macrosize and structure-controllable ultralong Fe3O4 NWs-GO aerogel with interpenetrating microstructure was prepared.In this section,the Fe3O4 NWs-GO materials were characterized by infrared spectroscopy(FT-IR),X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),Raman spectroscopy(Raman),thermal gravimetric analysis(TGA)and Field emission scanning electron microscopy(FESEM),and the results showed that the prepared magnetic Fe3O4NWs had a diameter of about 30 nm,a length of micrometers,and were of uniform distribution;At the same time,the ultralong Fe3O4 NWs-graphene composite was set up and interspersed to form a special structure of " net-in-net".Moreover,the vibrating sample magnetometer(VSM)and four-probe tester were tested and revealed that the the composite was high ferromagnetic and conductive.On this basis,the growth mechanism of ultralong Fe3O4 NWs was systematically analysised:Na2S2O3 could not only reduce Fe(OH)3 to transform to Fe(OH)2 with its own weak reduction,but also interacte with iron ions to limit the reaction precipitation rate,while the soft template PEG could control the growth direction of Fe3O4.Finally,one-dimensional ultralong Fe3O4 NWs were obtained.2.It was discussed the effects of the loading morphology and addition ratio of Fe3O4 NWs and GO on the electromagnetic shielding and microwave absorption properties of ultralong Fe3O4NWs-GO hybrid particles with interpenetrating microstructure.And the results showed that the interpenetrating microstructure could contribute to improve the electromagnetic shielding and microwave absorption performance.When the addition ratio of Fe3O4 NWs/GO was 1:2,the electromagnetic shielding effectiveness was the best,mainly absorption.and the maximum reflection loss(RL)of the microwave absorption performance could reached 37.89 dB with the thickness of 2 mm and the absorption bandwidth(EAB)of 5 GHz,the impedance matching was optimal.Because the formation of interpenetrating heterointerface structure increased the dielectric relaxation process and improved the microwave absorption characteristics.3.The three-dimensional Fe3O4 NWs-GO aerogel/epoxy composite material with interpenetrating network structure was obtained and systematically studied the effects of Fe3O4 morphology and addition ratio on the electromagnetic shielding and microwave absorption properties.Compared to Fe3O4 NPs loading aerogel,the "net-in-net" structure formed by the one-dimensional ultralong Fe3O4 NWs-GO aerogel with interpenetrating structure could stabilize the internal architecture of the three-dimensional material,increase the surface area of the heterostructure,and enhance the electromagnetic interface effect and multi-loss synergy between dielectric loss and magnetic loss.When the addition ratio of Fe3O4NWs/GO was 1:2,the electromagnetic shielding performance was up to 32 dB,and the efficiency was mainly absorption.When the addition ratio was 1:1,the maximum reflection loss of microwave absorption reached 46.51 dB with the thickness of 2 mm and the EAB of 10 GHz,and the impedance matching was better.Therefore,the ultralong Fe3O4 NWs-GO aerogel with interpenetrating microstructure was an ideal high-performance new material with both electromagnetic shielding and microwave absorption properties. |
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