188宝金博页面版

This journal is©the Owner Societies 2020 Phys. Chem. Chem. Phys.Citethis:DOI:10.1039/d0cp00290aHeterogeneous iron–nickel compound/RGOcomposites with tunable microwave absorptionfrequency and ultralow filler loadingMiaomiao Zhang, ab Zhiyang Jiang, ab Haoxu Si, ab Xuefeng Zhang, c Caixia Liu, abChunhong Gong, * ab Yahong Zhang ab and Jingwei ZhangbWe fabricated heterogeneous iron–nickel compound/reduced graphene oxide (RGO) composites to obtainlightweight and high-efficiency microwave absorption materials with tunable absorption frequency. Using afacile hydrothermal route in combination with calcination at varying temperatures of 500–700 1C, themagnetic components Fe 0.64 Ni 0.36 , Fe 0.64 Ni 0.36 @Fe 2 Ni 2 N, and Fe 2 Ni 2 N were obtained. Due to strong inter-facial polarization and dipole polarization as well as the conductive network formed by the substantialnumber of interfaces, all the magnetic RGO hybrids presented remarkable electromagnetic wave attenuationability even when the filler content was only 5.2 wt%. More importantly, the optimization of reflection loss andtunable absorption frequency could be successfully realized by tuning the hybrid architecture and electro-magnetic properties. This work reveals the mechanism of polarization-related dielectric relaxation of RGO,which provides new opportunities for designing lightweight and highly efficient microwave-absorbing materialsby fully utilizing the hetero-interfacial effects.1. IntroductionUndesirable electromagnetic (EM) wave has been causing inter-ference and pollution, and even the harm to nervous systems ofhuman bodies. 1–3 The development of high-performance micro-wave absorption materials has thus attracted great attention inaddressing such problems in the areas of local internet (2.45,5.0, 19.0, 22.0 and 60.0 GHz), mobile communication devices(0.8–1.5 GHz) and radar systems (11.7–12.0 GHz). 4 Microwaveabsorption materials with tunable frequency and selectiveabsorption are expected in practical applications, but the develop-ment of such materials remains a great challenge. 5–7Among the various microwave-absorbing materials, reducedgraphene oxide (RGO) is considered as the most promising high-ef f i ciency and lightweightelectromagneticwaveabsorptionmaterialdue to its ultra-high specific surface, intensive dielectric loss,excellent electrical conductivity, etc. 8–13 However, the mismatchbetween the relatively high dielectric loss and the low magneticloss ofsingle-component RGO has limited its microwave absorptionproperty. 14–16 Based on the electromagnetic complementary theory,adding magnetic components to RGO to enhance the magnetic losswould be an effective strategy to increase the relative complexpermeability (m r = m r 0 ? jm r 00 ) such that it is close to or matchesthe relative complex permittivity (e r = e r 0 ? je r 00 ). 17 Unfortunately, toachieve effective permeability values, the filler content often needstoexceed30wt%,whichleadstosubstantiallyheavyabsorbentsandrestricts their practical application as lightweight and effectivemicrowave-absorbing materials. 18–20 Therefore, to design light-weight absorbers with low density and a low absorbent fillingcontent, the main mechanism of loss in RGO-based hybridmaterials should be dielectric loss rather than magnetic loss.The dielectric loss behavior mainly stems from conductiveloss and interfacial polarization. 21,22 Hence, the ef f ect of thehigh conductivity of RGO is two-sided, i.e., though properconduction loss plays a key role in the dielectric loss, the overlyenhanced conductivity leads to stronger reflection of the incidentwave and causes poorer absorption capacity. Therefore, somerecent studies revealed that satisfactory reflection loss (RL) valuesfor RGO/wax composites were primarily achieved at low fillingratios due to the reduced impedance mismatch between thematerials and free space. 23 However, decreasing the conductivitywill result in weak attenuation owing to dramatically decreasedconduction loss. Thus, to construct carbon-based compositeswith ef f ective electromagnetic parameters for lightweight andhigh-ef f i ciency microwave absorption, relaxation polarizationloss must play an important role. 24,25a Institute of Functional Polymer Composites, College of Chemistry and ChemicalEngineering, Henan University, Kaifeng 475004, China.E-mail: gong@henu.edu.cn; Fax: +86-371-23881589; Tel: +86-371-23881589b National & Local Joint Engineering Research Center for Applied Technology ofHybrid Nanomaterials, Henan University, Kaifeng 475004, Chinac Innovative Center for Advanced Materials, Hangzhou Dianzi University,Hangzhou 310012, ChinaReceived 17th January 2020,Accepted 22nd March 2020DOI: 10.1039/d0cp00290arsc.li/pccpPCCPPAPERPublished on 24 March 2020. Downloaded by TONGJI UNIVERSITY LIBRARY on 4/25/2020 2:53:08 PM. View Article OnlineView Journal