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材料研究学报, 2024, 38(1): 1-13 DOI: 10.11901/1005.3093.2023.114

综述

石墨烯基吸波复合材料研究进展

徐东卫1,2, 王瑞琪1, 陈平,1

1 大连理工大学化工学院 精细化工国家重点实验室 大连 116024

2 郑州航空工业管理学院材料学院 郑州 450046

Research Progress of Graphene-based Absorbing Composites

XU Dongwei1,2, WANG Ruiqi1, CHEN Ping,1

1 State Key Laboratory of Fine Chemicals, School of Chemical Engineering, Dalian University of Technology, Dalian 116024, China

2 School of Material Science and Engineering, Zhengzhou University of Aeronautics, Zhengzhou 450046, China

通讯作者: 陈平，教授，pchen@dlut.edu.cn，研究方向为高性能高分子材料与先进聚合物基复合材料结构与功能一体化设计与制备

责任编辑: 吴岩

收稿日期: 2023-02-04   修回日期: 2023-04-08  

基金资助: 国家重大研究计划(2019-ZD-380-12)
兴辽英才计划(XLYC1802085)
大连市科技创新基金重大项目(2019J11CY007)
中央高校基本科研基金(DUT18GF107)
航空科学基金(20173754009)
河南省自然科学基金(232300420332)
河南省高等学校重点科研项目(23A430006)

Corresponding authors: CHEN Ping, Tel:(0411)84986100, E-mail:pchen@dlut.edu.cn

Received: 2023-02-04   Revised: 2023-04-08  

Fund supported: National Key Research Program(2019-ZD-380-12)
Liaoning Revitalization Talents Program(XLYC1802085)
Dalian Science and Technology Innovation Fund Project(2019J11CY007)
Fundamental Research Funds for the Central Universities(DUT18GF107)
Aviation Science Foundation(20173754009)
Natural Science Foundation of Henan Province(232300420332)
Key Scientific Research Project of Higher Education Institutions in Henan Province(23A430006)

作者简介 About authors

徐东卫，男，1990年生，博士

摘要

电子信息技术的迅速发展，致使电磁污染及干扰问题愈加严重，研制具有“宽、薄、轻、强”综合优异性能的吸波材料显得尤为重要。石墨烯材料因其具有轻质、高导电、大比表面积、强介电损耗等优点，但其阻抗匹配性能较差，损耗机制单一。对其进行异质元素掺杂或进行形貌结构设计，可有效改善其阻抗失配问题。本文基于电磁波吸收理论，阐述了不同维度石墨烯基吸波复合材料的研究进展，详细讨论了不同石墨烯基吸波复合材料的性能和吸波机理。还讨论了石墨烯吸波材料领域目前研究工作中存在的一些不足，最后针对石墨烯基吸波材料未来的研究方向和发展前景进行了展望。

关键词： 评述; 石墨烯; 微波吸收; 结构调控; 多功能吸波材料; 阻抗匹配

Abstract

With the rapid development of electronic information technology, electromagnetic pollution and interference have become more and more serious. It is particularly important to develop microwave absorption materials with comprehensive excellent performance of "wide, thin, light and strong". Graphene materials have the advantages of light weight, high conductivity, large specific surface area and strong dielectric loss, however, the impedance matching performance is poor and the loss mechanism is single. Interestingly, the impedance mismatch can be effectively improved by doping heterogeneous elements or designing morphology and structure. Herein, based on electromagnetic wave absorption theory, this paper describes the research progress of different dimensions of graphene-based absorbing materials, and discusses the properties and microwave absorbing mechanism of different graphene-based absorbing materials in detail. The shortcomings of current research work in the field of graphene absorbing materials are also discussed. Finally, the future research direction and development prospect of graphene-based absorbing materials are prospected.

Keywords： review; graphene; microwave absorption; texture regulation; multifunctional absorbing material; impedance matching

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本文引用格式

徐东卫, 王瑞琪, 陈平. 石墨烯基吸波复合材料研究进展[J]. 材料研究学报, 2024, 38(1): 1-13 DOI:10.11901/1005.3093.2023.114

XU Dongwei, WANG Ruiqi, CHEN Ping. Research Progress of Graphene-based Absorbing Composites[J]. Chinese Journal of Materials Research, 2024, 38(1): 1-13 DOI:10.11901/1005.3093.2023.114

各种电子设备产生的电磁辐射污染环境和干扰科学仪器的正常使用[1~5]，已经成为公害。因此，设计和制备微波吸收材料在民用和军事领域都有重要的意义。吸波材料可将电磁能转化为热能或其他形式的能量加以耗散。对理想电磁波吸收材料的要求是质轻、薄、吸收频带宽和吸收特性强。铁氧体、金属微粉、羰基铁以及纳米金属氧化物等磁性材料通过自然共振和畴壁共振等方式衰减电磁波，有磁损耗高、原材抖广泛、成本低和制备技术门槛低等优势[6~8]。但是，磁性吸波材料易团聚、密度大和高温特性差。同时，作为粉末型吸收剂，磁性吸波材料的吸收损耗机理单一、整体吸收频带窄、耐腐蚀性差和机械性能较差。

纳米碳材料是一种极具应用潜力的介电损耗型吸波材料。石墨烯材料具有独特的蜂窝状孔壁及单原子层厚度的二维片层状结构和优异的性能，且其质轻、耐腐蚀、导电和具有独特的孔隙结构，受到了极大的关注[9~12]。但是，石墨烯材料的高电导率，使较多的电磁波在其表面反射而不能进入材料内部衰减。研究发现，将介电损耗型石墨烯与其他损耗型吸波材料复合可明显改善其电磁匹配特性，提高吸波性能和拓宽吸波频段。例如，将石墨烯与导电高分子、磁性金属(合金)、金属氧化物等复合，可调控其电磁性能[10~12]。本文基于电磁波吸收理论综述石墨烯基吸波复合材料的研究进展，讨论不同石墨烯基复合吸波材料的性能和机理，并展望其发展方向。

1 电磁波吸收的基本理论和性能

1.1 电磁波吸收的基本理论

电磁波在传播过程中遇到阻挡介质时，在入射面或界面发生反射和透射(图1)。如果原传播介质的波阻抗与材料的波阻抗不匹配，就会有一部分电磁波反射，一部分透射到介质内。阻抗越不匹配，反射的电磁波越多。只有原传播介质的波阻抗与材料的波阻抗匹配，电磁波才能入射到材料内部。在材料内传播的电磁波与材料相互作用转化为其他形式的能量(如机械能、电能和热能等)，即产生电磁波损耗[13]。这表明，吸波材料的吸波性能决定于：(1) 阻抗匹配特性，即减少电磁波在材料表面的反射；(2) 衰减特性，即进入材料内的电磁波被材料吸收而损耗。

图1

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图1   电磁波的传输及和吸波材料作用的示意图

Fig.1   Schematic diagram of interaction between MAMs and microwaves


根据损耗机理，吸波材料分为介电损耗材料和磁损耗材料。介电损耗材料包括碳材料、非磁性金属粉末、导电聚合物、非磁性金属氧化物以及非氧化物陶瓷。这类材料的强度高、耐高温、导电性好和密度低，但是其有效吸收带宽(Effective absorption bandwidth，EAB)小和吸波性能不高。磁损耗材料，主要有磁性金属粉末及化合物、铁氧体以及羰基铁。磁损耗材料的应用受到密度高和稳定性低的限制。吸波材料的介电损耗因子和磁损耗因子分别定义为tanδE = ε″/ε′和tanδM = μ″/μ′，用以表征其介电损耗能力和磁损耗能力。介电损耗性能，主要源于电导损耗和极化弛豫损耗。电磁波进入吸波材料后载流子在电场作用下形成电流，电能转化为热能或其他形式的能量而耗散。如果电导率过高，则入射电磁波大量反射，从而使电磁波的衰减性能降低[14,15]。极化弛豫损耗，包括离子极化损耗、电子极化损耗、偶极子弛豫极化损耗和界面极化损耗。离子极化是正负离子之间的相对位移引起的，电子极化源于组成原子相对于原子核位置的变化引起的偶极矩的改变。这两种极化损耗发生在紫外线、可见光和红外光频率，微波频率范围的损耗可以忽略。偶极弛豫极化，是偶极矩沿电场方向旋转产生的，对介电损耗的影响较大。可根据德拜方程[16,17]

ε'=ε∞+(εs-ε∞)11+ω2τ2
ε″=(εs-ε∞)ωτ1+ω2τ2

分析弛豫损耗。复介电常数的实部(ε′)与虚部(ε″)的关系为

ε'-εs+ε∞22+ε″2=(εs-ε∞2)2

其中εs、ε∞和τ分别为静态介电常数、相对介电常数和极化松弛时间。复介电常数的实部与虚部的关系是一个半圆，称为Cole-Cole半圆，每一个Cole-Cole半圆代表一次极化松弛过程。半圆上的点分别对应由德拜方程计算出的介电常数在某一频率下的实部和虚部。界面极化出现在非均质介质的界面，是电子或离子在外电场作用下在界面处聚集引起的。介电材料具有宽频带微波吸收性能，但是其低频吸收效果较差。

磁损耗是外界对磁性材料所做的功在磁化或退磁过程中功转化为热，主要是磁性材料的滞后损耗、多畴壁共振、涡流效应、自然共振和交换共振引起的。在弱磁场中的滞后损耗和发生在低频(< 2 GHz) 的多畴壁共振引起的损耗，都可忽略[18]。导体在非均匀磁场中运动或在时变磁场中运动时，导体中的感应电流引起损耗称为涡流损耗。依据趋肤效应，涡流损耗可表示为[19]

C0=μ″μ'2f=23πμ0δd2

其中μ0、σ、d分别为真空磁导率、电导率和吸波剂厚度。由 式(4)可知，若磁损耗只与涡流损耗有关，则C0应为常数，不随频率变化。此外，介电损耗和磁损耗的协同作用使吸波材料具有优异的电磁波吸收性能和良好的阻抗匹配。但是，吸波材料的阻抗匹配与衰减性能之间仍然存在冲突，空心结构、蛋黄-壳结构、核-壳结构、多孔结构和调控成分可协调阻抗匹配和电磁波衰减性能。衰减常数α定义为[20]

α=2cπfμ″ε″-μ'ε'+μ″ε″-μ'ε'2+(μ'ε″+μ″ε')2

基于以上理论，合理设计结构和组成协同耦合效应使其具有复合杂化粒子微结构，可实现性能指标的优化配置，从而制备出具有特定组成、结构和性能的石墨烯基多功能复合吸波材料。

1.2 电磁波的吸收性能的测量

使用网络分析仪(NA)可测量电磁波吸收性能参数。网络分析仪，分为标量网络分析仪(SNA)和矢量网络分析仪(VNA)。在实际应用中，用SNA无法测量电磁参数(复介电常数和复磁导率)等复杂信号。用VNA可在更大的频率范围内动态地发送/接收和记录数据。使用最多的测量技术是传输线测量技术，包括同轴电缆和波导腔以及自由空间测量技术[21]。图2简要地给出了三种测量任何吸波材料吸波性能的主要技术。

图2

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图2   三种类型吸波性能测量技术示意图[21]

Fig.2   Schematic diagram of three different types of microwave absorption performance measurement techniques (a) coaxial line method; (b) waveguide method; (c) free space method[21]


使用同轴线法(图2a)时，被测样品是一个同轴圆环，外部直径为7 mm，内部直径为3.04 mm。这种方法的主要优点是使用相同的样品可在任何频率范围进行测量，所需试样量少，其缺点是重复性差。波导方法(图2b)使用矩形样品，波导的尺寸取决于测量频率。值得注意的是，波导的尺寸随着测试频率的增加而减小。这种方法的主要优点是制备简单，缺点是测试频率范围较窄，且需要的波导的数量较多。另外，用波导方法测量须将样品与波导腔完好密封以排除空气间隙产生的测量误差。自由空间法(图2c)的接触测量系统由被测样品两侧的两个天线组成，一个用于发射信号，另一个接收信号，分别通过天线与矢量网络分析仪的发射、接收端口相连。可调节两个喇叭天线的位置改变电磁波的入射角，以测量吸波材料在不同入射角的电磁波反射损耗值。这个方法的突出优点，是可覆盖较宽的测量频率范围、进行变温测量且不会破坏试样。此法的主要缺点是所需样品较多，且不能在低频段测试。弓形法是由弓形装置和信号源、网络分析仪等设备组成的测试系统。分别测量样品台上放置的标准板和试样，根据入射电磁波经标准板和试样反射回来的电磁波的功率计算材料的吸波性能。屏蔽室法，是用屏蔽室内外的接收和发射天线测试透射波的衰减，用于计算屏蔽效能。

2 不同维度石墨烯基复合吸波材料

独特的蜂窝状孔壁和单原子层厚度的二维片层状结构，使石墨烯具有优异的性能，如轻质、高比表面积、高电导性和较高的介电常数。同时，石墨烯边缘的大量悬空键在外电场作用下更易产生极化弛豫而衰减电磁波；用氧化还原法制备的还原氧化石墨烯，其表面有大量残余的含氧官能团和缺陷。这些含氧官能团和缺陷，不仅降低石墨烯的电导率和提高自身阻抗匹配特性，还作为极化中心有利于电磁波的吸收和衰减[22]。更为重要的是，高比表面积的石墨烯很适合做为基体负载功能化纳米粒子，可提高纳米粒子的分散性和减少团聚，还能在微纳米尺度优化设计结构和性能，从而制备出具有特定结构、组成和性能的多功能石墨烯基吸波复合材料。

2.1 石墨烯片层复合吸波材料

石墨烯吸波材料较高的电导率使电磁波反射，且因没有能带隙而不易调控其介电性能。在石墨烯中进行原子掺杂或与其他损耗型吸波材料复合，可改善其电磁匹配特性和提高吸波性能。

Cao等[23]研究了超薄石墨烯复合材料在323~473 K和X波段的介电常数和微波吸收性能。结果表明，化学石墨化超薄石墨烯在高温下微波吸收性能较高。在323~473 K的X波段其最大损耗正切和最小反射损耗分别为1.32和-42 dB，吸收频带几乎覆盖了整个X波段。这表明，超薄石墨烯是一种很有前途的轻质高效微波吸收材料。Zheng等[24]用简便的原位热分解方法将超顺磁性Fe3O4纳米晶体锚定在疏水性石墨烯纳米片上，构筑出协同电磁波吸收剂(图3)。结果表明，Fe3O4纳米晶体以化学键结合方式均匀地负载在石墨烯纳米片的表面，没有明显的团聚或较大的空位。Fe3O4-石墨烯杂化物具有疏水性和超顺磁性，良好的阻抗匹配和协同作用其具有增强的电磁波吸收特性。

图3

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图3   疏水Fe3O4-石墨烯杂化物的制备流程示意图[24]

Fig.3   Schematic illustration for the formation of the hydrophobic Fe3O4-graphene hybrids and their application for electromagnetic wave absorption[24]


Wang等[25]制备的石墨烯@Fe3O4纳米簇@碳@MnO2纳米片阵列层状化复合材料，其微波吸收性能明显高于石墨烯@Fe3O4。Wang等[26]制备了合理结构的石墨烯层状复合材料(NiFe2O4/N-GN/ZnO)，发现其低填充量为20%(质量分数)时其最强的反射损耗高达-70.7 dB，有效吸收频带为3.5 GHz。Liu等[27]在磁性装饰的石墨烯上生长CuS纳米薄片，设计了微波吸收性能优异的杂化石墨烯纳米复合材料，研究了十六烷基三甲基溴化铵(CTAB)对CuS特殊纳米结构的影响、纳米复合物的生成和微波吸收机理。

Yan等[28~30]基于纳米级柯肯德尔效应分别将超精细NiFe2O4、CoFe2O4、NiCo2O4空心纳米颗粒锚固在石墨烯片层表面，制备出不同中空纳米颗粒/还原氧化石墨烯杂化物复合吸波材料，都具有优异的电磁波吸收性能。Zhang等[31]用微波辅助水热法制备CoS2/rGO纳米杂化物(图4)，研究了rGO比例不同的这种材料的微波吸收性能。形态分析结果表明，CoS2纳米颗粒均匀地嵌入rGO中而没有聚集。改变rGO比例，即可调节CoS2/rGO纳米杂化物的复介电常数。厚度为2.2 mm的CoS2/rGO 1∶2的复合材料，频率为10.9 GHz时最小反射损耗(RL)为-56.9 dB，有效吸收频带为4.1 GHz。

图4

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图4   CoS2/rGO纳米杂化物的结构和性能[31]

Fig.4   Structure and properties of CoS2/rGO composites[31]


2.2 石墨烯微球

石墨烯片层间的分子间作用力和π-π作用，极易使其发生堆叠团聚。构筑三维空心微球结构不仅能阻止石墨烯片团聚,还能使其结构规整、尺寸可调，且具有较大的比表面积和优异的性能。

Li等[32]基于成分调控和微纳结构设计，用简单的溶剂热法和退火制备出具有分层结构的三维Co/CoO/RGO微球(CCOR)。调节磁性Co/CoO颗粒和高导电RGO纳米片之间的协同效应，即可调节其电磁参数。这样制备出的CCOR复合微球具有优异的微波吸收性能，其最大反射损耗值为-50.1 dB，有效吸收带宽达到6.56 GHz，覆盖整个X波段频率。Zeng等[33~35]用油包水(W/O)乳化与高温煅烧两步法相结合的自组装技术，将磁性纳米粒子引入具有空心结构的石墨烯微球中，制备出三种负载不同磁性纳米粒子的还原氧化石墨烯复合微球(Air@rGO€Fe3O4、Air@rGO€Co和Air@rGO€Ni)(图5)。结果表明，这三种磁功能化石墨烯复合微球都具有优异的吸波性能和强耐腐蚀性，其电磁波吸收强度和有效吸收频带均大于单一还原氧化石墨烯和纯磁性纳米粒子。

图5

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图5   Air@rGO€Fe3O4空心微球的制备示意图[33]

Fig.5   Schematic illustration of the self-assembly process of Air@rGO€Fe3O4 microspheres[33]


Li等[36]将多轴静电纺丝与冷冻干燥和煅烧工艺相结合制备了中空结构可控的石墨烯微球(HGAS)和球中球石墨烯微球(BGAS)(图6)。良好的介电损耗和阻抗匹配性能，使石墨烯微球(HGAS)在-52.7 dB的反射损耗最小和有效吸收带宽较宽(7.0 GHz)。厚度为3.4 mm的BGAS复合材料，其有效吸收频带达到9.3 GHz。Cui等[37]用简单快速的超声波喷涂技术制备出三维(3D)褶皱RGO/MXene/Fe3O4微球(FMCM)，将还原氧化石墨烯(RGO)、MXene纳米片和Fe3O4纳米粒子组装在一起实现了综合优势互补。调整GOx、MXene和Fe3O4的比例，即可制备出不同Fe3O4含量的FMCM。FMCM-3复合材料具有最好的吸波性能，厚度为2.9 mm时最小反射损耗为-51.2 dB，有效吸收频带为4.7 GHz。FMCM优异的吸波性能，源于3D多孔结构和合理的材料组成。

图6

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图6   空心氧化石墨烯气凝胶微球和球中球氧化石墨烯气凝胶微球的示意图[36]

Fig.6   Schematic diagram of hollow graphene oxide aerogel spheres (a) and ball-in-ball graphene oxide aerogel spheres (b)[36]


Ye等[38]以乙基纤维素为骨架、以环氧树脂为粘合剂，用溶剂挥发法制备出RGO-CIP复合微球。这种复合微球将石墨烯(RGO)与羰基铁粉(CIP)有效结合产生了多种损耗机制的协同作用，使其具有良好的电磁吸收性能。Cai等[39]使用独特的喷涂和交联凝固方法制备出多孔结构可调的钴@石墨烯气凝胶微球(GCoAMs)，其分层多孔结构和石墨烯/金属Co 杂化成分使其具有强而宽的微波吸收性能。GCoAMs负载量为1.5%(质量分数)、厚度为2.2 mm的样品，在13.18 GHz的最小反射损耗高达-70.4 dB；样品厚度为1.98 mm的样品，其有效吸收频带达到 5.65 GHz。

Liu Z H等[40]将超声喷涂技术与包覆工艺相结合将MoS2、氧化石墨烯(GO)和聚多巴胺组装成三维MoS2/RGO/NC褶皱微球。复杂的结构、互补的损耗机制和良好的阻抗匹配，使其具有优异的微波吸收性能。厚度为3.1 mm的MoS2/RGO/NC褶皱微球，其最小反射损耗达到-60.4 dB。调整微球的成分，厚度为2.9 mm时其有效吸收带宽高达6.1 GHz (11.9~18.0 GHz)。Wang等[41]用电荷驱动自组装方法制备出褶皱的还原氧化石墨烯包裹聚合物衍生碳(CS@rGO)微球。研究表明，这种独特的三维(3D)多界面结构使其具有更高的微波吸收性能。调整电荷驱动的自组装循环时间，可优化CS@rGO微球的介电性能和阻抗匹配特性。

2.3 石墨烯纤维

石墨烯纤维具有良好的导电性能、机械强度和柔性，做为轻质导线可在极宽的温度范围内工作。用石墨烯纤维还可制备出柔性织物穿戴在人体表面，作为纤维状电池或者电容器的电极使储能器件可穿戴，利用电热转换实现医疗保健、电磁屏蔽和微波吸收。

Tang等[42]报道了一种高性能石墨烯纤维的优化和制备策略(图7)，用湿纺丝技术制备出高导电性、强韧性和高强度且表面极少缺陷的原始石墨烯纤维。优异的力学性能和多功能特性，使其在能量收集、电磁屏蔽、超级电容器、柔性电池、传感器等领域有广阔的应用前景。Hou等[43]设计构筑了吸湿性多孔石墨烯气凝胶纤维(LiCl@HGAFs)，具有高效水分捕获、热量分配及微波吸收的集成功能。值得注意的是，包埋了水的LiCl@HGAFs表现出宽频带的微波吸收，有效吸收带宽为9.69 GHz。

图7

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图7   f-GO、f-GO纤维和还原f-GO纤维的制备示意图[42]

Fig.7   Schematic illustrating the preparation processes of f-GO, f-GO fiber, and reduced f-GO fiber[42]


Zheng等[44]提出一种高导电石墨烯包覆策略，首次用同轴湿纺和冷冻干燥制备出一种皮芯型异质结构石墨烯/MXene纤维气凝胶(图8)。这种气凝胶，具有高效持久的电磁屏蔽性能、高疏水性、高导电性、高效油水分离特性和高温隔热性能。Sheng等[45]用简便的湿法化学合成和静电自组装方法制备出具有分层核-壳结构和垂直排列的石墨烯边缘平面的3D rGO/Ni纳米纤维。这种独特的3D rGO/Ni纳米纤维较大的比表面积和有效的界面极化损耗，使其具有高效的微波吸收特性。调节rGO/Ni的质量比，即可控制纳米纤维的3D微观结构和吸收性能。rGO/Ni质量比为1∶3时，在只含15%rGO/Ni(质量分数)纳米纤维的情况下，其衰减为-50.52 dB，较薄匹配厚度为2.0 mm的材料其有效吸收带宽达到4.2 GHz。

图8

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图8   皮芯型石墨烯/MXene纤维气凝胶的制备及其应用[44]

Fig.8   Schematic illustration of fabrication for rGO/MXene fiber aerogel and EMI shielding and oil/water separation applications of the fiber aerogel[44]


目前，湿法纺丝仍是制备高性能石墨烯纤维的主要工艺，通过基元材料优化、制备过程调控和采用高温热还原，可制备出热导率高于碳纤维和碳纳米管纤维的石墨烯纤维。但是与碳纤维和碳纳米管纤维相比，石墨烯纤维的强度和电导率等基本特性以及制备工艺技术的成熟度，依然有较大的差距。对纤维的结构分析表明，限制石墨烯纤维性能的因素主要有：(1) GO片层的制备过程产生不可避免的缺陷结构。GO是湿法纺制石墨烯纤维的主要原料，但是其表面有大量的含氧官能团及结构缺陷，进行高温还原和石墨化处理也难以将其完全去除。这些结构缺陷显著影响石墨烯纤维的力学强度、导电、导热性能；(2) 石墨烯纤维内微米级石墨烯片层的聚集态结构，包括片层的取向、结晶、间隙等二级结构，使石墨烯纤维内的片层形成部分褶皱结构，使石墨烯片层取向度降低而影响纤维的性能；(3) 石墨烯纤维的密度较低。现有的石墨烯纤维其密度仍低于碳纤维、石墨纤维以及碳纳米管纤维，较低的堆叠密度决定纤维内部的孔隙结构，限制了石墨烯的本征优异性能传递。因此，只有进一步优化石墨烯纤维的制备和处理过程、修复石墨烯的结构缺陷、提高石墨烯片层晶区尺寸和取向度等，才能制备出性能更高的石墨烯纤维。

2.4 石墨烯泡沫

构筑三维“泡沫型”结构石墨烯，可实现超宽频电磁响应。除了三维结构内的多重反射及散射机制，错综复杂的多孔网络结构充当耦合电路，使其在电磁场作用下产生感生电流而增强了电导损耗。与典型的二维结构石墨烯基吸波复合材料相比，这种具有特殊三维结构的“泡沫型”石墨烯具有更优异的电磁吸收特性

Chen等[46]进行各向异性设计，有针对性地构建出具有长程排列高度多孔结构的单向石墨烯泡沫 (UGF)、系统研究了2~18 GHz下的电磁吸收性能与入射电磁波方向和极化方向之间交叉角φ的函数关系。在平面内旋转样品即可调节UGF的反射损耗(RL)和峰值频率。同时，介电损耗和感应电流引起的双吸收机制，使单向石墨烯泡沫具有10.9 GHz的超宽吸收频带。Liu等[47]用自组装的水热反应和冷冻干燥工艺制备出具有高孔隙率和开放网状结构的超轻型N-掺杂石墨烯泡沫。与纯石墨烯泡沫相比，N杂原子有利于构建开放的网状壁并调整电性能，从而产生强大的电磁波吸收能力和较宽的吸收带宽，最大反射损耗在3.5 mm处为-53.9 dB，超过-10 dB的吸收带宽为4.56 GHz。根据吸波机理分析，高效的电磁波吸收性能主要源于增强的偶极/界面极化、多重散射、微米级圆形导电结构以及平衡的阻抗匹配。

Chen等[48]用溶剂热法制备了超轻多壁碳纳米管/石墨烯泡沫材料(CGFs)，调节MWCNT的负载量和热还原温度即可调控CGFs复合材料的复介电常数和电导率。MWCNT的加入显著提高了CGFs复合材料的低频微波吸收强度。在C波段(4~8 GHz)和X波段(8~12 GHz)，最小反射损耗值为-39.5 dB，平均吸收强度超过22.5 dB。Zhang等[49]构筑了超轻且高度可压缩的石墨烯泡沫(GF)，只需进行物理压缩即可调整微波吸收性能。在压缩应变为90%的条件下，GF达到了93.8%(60.5 GHz/64.5 GHz)的超宽频带吸收范围(图9)。

图9

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图9   三维“泡沫型”结构石墨烯的电磁波损耗模型及其典型性能对比[49]

Fig.9   Schematic representation of the MA mechanism for the GF and typical performance comparison diagram[49]


Xu等[50~52]用高温水热还原自组装法将不同磁性纳米粒子通过化学还原原位沉积在石墨烯片上，制备出多种具有优异电磁波吸收性能及强耐腐蚀性的磁性石墨烯泡沫复合材料(MGF@Co、MGF@Ni和MGF@Fe3O4) (图10)。与石蜡填充复合制备的微波吸收材料，其最小反射损耗值分别为-65.8、-58.7、-64.4 dB，最大有效吸收频带达到13.85、13.62、13.3 GHz，其综合性能均优于文献报道的大多数石墨烯基复合材料。Huang等[53]报道了一种基于3D石墨烯泡沫(3DG)的高效太赫兹波吸收器。由于表面反射微弱和巨大的内部吸收，在0.1~1.2 THz的频率范围内其太赫兹吸收性能极为出色。精确控制3DG的恒定特性，即可实现19 dB的反射损耗，有效吸收带宽覆盖法向入射时整个测量带宽的95%。更为重要的是，3DG的太赫兹吸收性能随着入射率的增加而明显提高，在入射角为45°时最大反射损耗值从19 dB增大到28.6 dB，有效吸收频带覆盖了测量带宽的100%。

图10

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图10   3D磁性石墨烯泡沫复合材料的制备工艺流程[50]

Fig.10   Fabrication process of 3D N-MGF@Co hybrids[50]


2.5 石墨烯气凝胶

根据其结构，可将石墨烯气凝胶(Graphene aerogels，GA)看作具有特殊结构或性能的石墨烯泡沫。作为典型3D多孔材料，优异的导热性、导电性以及轻质、高比表面积和孔隙率可控等特性，使其在锂电池、传感器、吸附、催化及电磁波吸收等领域有重要的应用前景。另外，高温退火处理可改善石墨烯气凝胶材料的介电性能和表面缺陷，有利于提高三维石墨烯网络的导电性和电导损耗，进而提高其电磁波吸收性能。

Zhang等[54]用简单的阳离子辅助水热处理工艺制备了具有良好分散性能和界面极化性能的超轻RGO气凝胶。RGO/石蜡复合材料在8.0~18.0 GHz的宽频带范围内具有优异的微波吸收性能。Wang等[55]用简便的溶剂热合成法将CoFe2O4(CFO)纳米颗粒嵌入N掺杂的还原氧化石墨烯(N-rGO)气凝胶中，制备出具有3D多孔结构的CFO/N-rGO气凝胶微波吸收材料。调节CoFe2O4的添加量，即可改善CFO/N-rGO气凝胶的电磁参数。氧化石墨烯(GO)与CoFe2O4的质量比为1∶2、低填充量较低(20%，质量分数)的复合材料在14.4 GHz处具有强反射损耗(-60.4 dB)，其有效吸收带宽达到6.48 GHz (11.44~17.92 GHz)。

Zhao等[56]用冷冻干燥结合热还原工艺制备出具有一维CoNi链和CNT修饰的杂化石墨烯气凝胶(GA-CNT-CoNi)(图11)。与GA和GA-CoNi气凝胶相比，浸入聚二甲基硅氧烷基体中的4%GA-CNT-CoNi(质量分数)具有最强的微波吸收性能。厚度为1.8 mm时最佳反射损耗值为-50.8 dB，有效吸收带宽达到8.5 GHz (18~26.5 GHz)，覆盖整个K频段。Zhao等[57]用原位溶剂热和碳化工艺开发了一种新型的CoNi/还原氧化石墨烯(rGO)气凝胶吸收剂。制备出的CoNi/rGO气凝胶具有超低密度(7 mg·cm-3)、分层的多孔结构和高表面积。根据吸收机理，良好的介电损耗及磁损耗、优异的阻抗匹配和多孔结构有助于微波吸收。

图11

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图11   CNT/RGO/CoNi链杂化气凝胶制备工艺示意图[56]

Fig.11   Schematic illustration of the fabrication process of RGO/CNT/CoNi chain hybrid aerogel[56]


Xu等[58~60]用化学还原自组装法并结合高温煅烧工艺，将不同磁性纳米粒子通过高温原位热解负载在石墨烯片上，制备出多种电磁波吸收性能和超疏水性能优异的磁性石墨烯气凝胶复合材料(SHGA@Fe3O4、SHGA@Co和HGA@Ni)。这种磁性石墨烯气凝胶复合材料(SHGA@Fe3O4、SHGA@Co、HGA@Ni)具有高比表面积、轻质、(超)疏水性能和优异的微波吸收性能，填充量约为5%(质量分数)时其最小反射损耗值分别为-57.9、-51.6、-52.3 dB，最大有效吸收频带达到13.2、13.2、13.1 GHz。Cheng等[61]首次开发出具有可开/关微波吸收性能的还原型氧化石墨烯/VO2复合气凝胶(图12)，其可开/关机制源于VO2的相变行为。随着温度的升高(> 68℃)VO2发生从单斜晶相到金红石相的相变，使其电导率和介电常数显着变化，从而使其具有关闭/打开可切换的微波吸收性能。

图12

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图12   复合气凝胶开/关微波吸收模式示意图[61]

Fig.12   “on to off” mode change for its MA performance during temperature rising[61]


2.6 其他类型的石墨烯复合材料

将石墨烯与纤维、树脂、陶瓷、金属粒子等复合制备的石墨烯基复合材料，可应用在能源、化工、生物、医药和超级电容器等领域。Zhang等[62]用热压法制备出PVDF/RGO复合材料，GO表面的含氧官能团能与PVDF上的含氟基团发化学反应使GO在PVDF中的分散性提高，然后用热压法又将GO还原而使其具有吸波和介电性能。RGO含量为3% (质量分数)的材料，其最大反射损耗为-25.6 dB出现在10.8 GHz，在8.48~12.80 GHz反射损耗均小于-10 dB。Ren等[63]以EP-CE树脂为基体材料、使用GNSs和GNSs/MWCNTs作为吸波剂，用溶液混合和浇注成型制备出树脂基吸波复合材料。加入GNSs能提高复合材料的吸波特性，GNSs用量为3%(质量分数)、匹配厚度为 4 mm的复合材料，其最小反射损耗为-21.4 dB。一维GNSs与二维MWCNTs之间的协同效应，使GNSs/MWCNTs/CE复合材料具有更高的吸波特性。Chen等[64]用原位生长(IS)和物理混合(PM)方法制备SiC晶须/还原氧化石墨烯气凝胶(SiCw/rGOA)，并研究了C-Si异质结对微波吸收性能的影响。结果表明，与纯rGOA相比，SiCw的掺入改善了自由空间和吸收体之间的界面阻抗，从而使其具有优异的微波吸收性能。Lv等[65]用石墨烯纳米片(GN)和中空玻璃微球(HGM)制备水泥基复合材料，发现GN与HGM结合使吸收性能提高。随着玻璃微球填充率的提高，吸收峰值和低于-5 dB的带宽先增大后减小。一种由凯夫拉(Kevlar)/石墨烯/环氧树脂复合材料组成的单层雷达吸波结构(RAS)，以铜薄膜作为背板或反射面RAS厚度为2.12 mm时12~18 GHz的回波损耗大于10 dB。美国加州大学制备的石墨烯基红外隐身涂层，改变反射光的波长以实现红外隐身。可将这种材料大面积涂覆在结构和平台表面，实现军事伪装。

3 吸波材料的发展趋势

为了实现良好的电磁匹配，研究人员越来越重视合理调节电磁参数、元件形貌和微观结构以平衡阻抗，实现优异的微波吸收。将石墨烯与磁损介质、导电聚合物、陶瓷等材料复合制备具有复杂多孔网络结构和异形不同维度结构的石墨烯基吸波复合材料，可实现各部件的优势和增强损耗能力。但是，石墨烯基吸波复合材料尚未大规模应用，本文总结的材料大多不能满足实际应用的要求。同时，大规模生产廉价、高质量的石墨烯面临着巨大的挑战。重要的是，目前文献报道的石墨烯基吸波复合材料主要用于研究不同结构的电磁组分调控及吸波性能，制备的吸波复合材料有填充量高、涂层厚、有效吸收频带窄等诸多不足，电磁波吸收性能还远低于期望值。同时，功能性粒子的粒径、各向异性和形貌对吸收剂的磁性能有重要影响，从而影响微波吸收剂的吸收性能。因此，需要进一步研究用不规则形貌和不同粒径修饰的石墨烯基复合材料。微波吸收材料由基体材料和吸波剂组成，其聚合物基体、石墨烯的尺寸和分散性以及石墨烯与基体之间的界面相互作用都影响材料的吸波性能，而石墨烯基材料的分散性制约其实际应用。

4 展望

近年来研究者对于石墨烯基吸波材料方面的研究做了很多有价值的工作。尽管如此，高性能多功能石墨烯基复合吸波材料的设计与制备依旧是未来研究的重点与难点。未来吸波材料发展方向主要集中在以下几点：

(1) 智能化设计。材料根据外界环境的变化调节自身的结构，使其电磁特性对环境做出最佳响应。

(2) 结构与功能一体化设计。用计算机技术模拟设计纤维状、蜂窝状或团簇状等吸波材料，在降低材料密度的同时拓宽吸波频带，研发具备吸波和承载等多重功能的新型纳米复合材料。

(3) 多光谱兼容性设计。材料能兼容多波段吸收，提高对先进探测系统的识别能力。

(4) 低维形态设计。纳米微粒、纳米纤维、颗粒膜等低维材料，其吸收频带宽、兼容性好、吸收强、质量轻，具有极大的发展潜力。

参考文献

Qiu H F, Zhu X Y, Chen P, et al.

Synthesis of ternary core-shell structured ZnOC@CoC@PAN for high-performance electromagnetic absorption

[J]. J. Alloys Compd., 2021, 868: 159260

DOI      URL     [本文引用: 1]

Zhan Y F, Xia L, Yang H, et al.

Tunable electromagnetic wave absorbing properties of carbon nanotubes/carbon fiber composites synthesized directly and rapidly via an innovative induction heating technique

[J]. Carbon, 2021, 175: 101

DOI      URL    

Li S S, Tang X W, Zhang Y W, et al.

Corrosion-resistant graphene-based magnetic composite foams for efficient electromagnetic absorption

[J]. ACS Appl. Mater. Interfaces, 2022, 14: 8297

DOI      URL    

Zhang Y L, Ruan K P, Shi X T, et al.

Ti3C2T x /rGO porous composite films with superior electromagnetic interference shielding performances

[J]. Carbon, 2021, 175: 271

DOI      URL    

Liu Q H, Cao Q, Bi H, et al.

CoNi@SiO2@TiO2 and CoNi@Air@-TiO2 microspheres with strong wideband microwave absorption

[J]. Adv. Mater., 2016, 28: 486

DOI      URL     [本文引用: 1]

Zhao H Q, Cheng Y, Zhang Y N, et al.

Core-shell hybrid nanowires with Co nanoparticles wrapped in N-doped porous carbon for lightweight microwave absorption

[J]. Dalton Trans., 2019, 48: 15263

DOI      PMID      [本文引用: 1]

Exploration of lightweight and thin electromagnetic (EM) wave absorption materials is still urgent because of the issues related to EM pollution. In this work, one-dimensional core-shell nanowires with Co nanoparticles embedded in N doped porous carbon (Co@NPC NWs) have been successfully fabricated for microwave absorption. The obtained Co@NPC composites with a pea-like structure have high loading of Co nanoparticles (68 wt%) encapsulated by the defective carbon shell. Thanks to these special characteristics, the Co@NPC NWs exhibit superb microwave absorption properties in comparison with the pristine nano-Co powder and NPC. The strong reflection loss (RL) of -48 dB could be achieved at a thickness of only 1.45 mm. In addition, the effective absorption bandwidth is up to 5.2 GHz. These superb absorption properties coupled with thin thickness endow the Co@NPC NWs with great potential for application in lightweight EM wave absorption.

Wen C Y, Li X, Zhang R X, et al.

High-density anisotropy magnetism enhanced microwave absorption performance in Ti3C2T x MXene@Ni microspheres

[J]. ACS Nano, 2022, 16: 1150

DOI      URL    

Zhu X Y, Qiu H F, Chen P.

A modified graphitic carbon nitride (MCN)/Fe3O4 composite as a super electromagnetic wave absorber

[J]. J. Mater. Chem., 2021, 9A: 23643

[本文引用: 1]

Chen C, Xi J B, Zhou E Z, et al.

Porous graphene microflowers for high-performance microwave absorption

[J]. Nano-Micro Lett., 2018, 10: 26

DOI      PMID      [本文引用: 1]

Graphene has shown great potential in microwave absorption (MA) owing to its high surface area, low density, tunable electrical conductivity and good chemical stability. To fully realize graphene's MA ability, the microstructure of graphene should be carefully addressed. Here we prepared graphene microflowers (Gmfs) with highly porous structure for high-performance MA filler material. The efficient absorption bandwidth (reflection loss ≤ -10 dB) reaches 5.59 GHz and the minimum reflection loss is up to -42.9 dB, showing significant increment compared with stacked graphene. Such performance is higher than most graphene-based materials in the literature. Besides, the low filling content (10 wt%) and low density (40-50 mg cm) are beneficial for the practical applications. Without compounding with magnetic materials or conductive polymers, Gmfs show outstanding MA performance with the aid of rational microstructure design. Furthermore, Gmfs exhibit advantages in facile processibility and large-scale production compared with other porous graphene materials including aerogels and foams.

Zhi D D, Li T, Li J Z, et al.

A review of three-dimensional graphene-based aerogels: synthesis, structure and application for microwave absorption

[J]. Composites, 2021, 211B: 108642

[本文引用: 1]

Yuan H R, Yan F, Li C Y, et al.

Nickel nanoparticle encapsulated in few-layer nitrogen-doped graphene supported by nitrogen-doped graphite sheets as a high-performance electromagnetic wave absorbing material

[J]. ACS Appl. Mater. Interfaces, 2018, 10: 1399

DOI      URL    

Li Z X, Li X H, Zong Y, et al.

Solvothermal synthesis of nitrogen-doped graphene decorated by superparamagnetic Fe3O4 nanoparticles and their applications as enhanced synergistic microwave absorbers

[J]. Carbon, 2017, 115: 493

DOI      URL     [本文引用: 2]

Zhang Z, Wang J D, Shang J, et al.

A through-thickness arrayed carbon fibers elastomer with horizontal segregated magnetic network for highly efficient thermal management and electromagnetic wave absorption

[J]. Small, 2023, 19: 2205716

DOI      URL     [本文引用: 1]

Wang H Y, Sun X B, Yang S H, et al.

3D ultralight hollow NiCo compound@MXene composites for tunable and high-efficient microwave absorption

[J]. Nano-Micro Lett., 2021, 13: 206

DOI      [本文引用: 1]

The 3D hollow hierarchical architectures tend to be designed for inhibiting stack of MXene flakes to obtain satisfactory lightweight, high-efficient and broadband absorbers. Herein, the hollow NiCo compound@MXene networks were prepared by etching the ZIF 67 template and subsequently anchoring the Ti3C2Tx nanosheets through electrostatic self-assembly. The electromagnetic parameters and microwave absorption property can be distinctly or slightly regulated by adjusting the filler loading and decoration of Ti3C2Tx nanoflakes. Based on the synergistic effects of multi-components and special well-constructed structure, NiCo layered double hydroxides@Ti3C2Tx (LDHT-9) absorber remarkably achieves unexpected effective absorption bandwidth (EAB) of 6.72 GHz with a thickness of 2.10 mm, covering the entire Ku-band. After calcination, transition metal oxide@Ti3C2Tx (TMOT-21) absorber near the percolation threshold possesses minimum reflection loss (RLmin) value of − 67.22 dB at 1.70 mm within a filler loading of only 5 wt%. This work enlightens a simple strategy for constructing MXene-based composites to achieve high-efficient microwave absorbents with lightweight and tunable EAB.\"Image missing\"

Wang Y H, Han X J, Xu P, et al.

Synthesis of pomegranate-like Mo2C@C nanospheres for highly efficient microwave absorp-tion

[J]. Chem. Eng. J., 2019, 372: 312

DOI      URL     [本文引用: 1]

Zhao H Q, Cheng Y, Liu W, et al.

Biomass-derived porous carbon-based nanostructures for microwave absorption

[J]. Nano-Micro Lett., 2019, 11: 24

[本文引用: 1]

Zhao T B, Jia Z R, Zhang Y, et al.

Multiphase molybdenum carbide doped carbon hollow sphere engineering: the superiority of unique double-shell structure in microwave absorption

[J]. Small, 2023, 19: 2206323

DOI      URL     [本文引用: 1]

Chu H R, Zeng Q, Chen P, et al.

Synthesis and electromagnetic wave absorption properties of matrimony vine-like iron oxide/reduced graphene oxide prepared by a facile method

[J]. J. Alloys Compd., 2017, 719: 296

DOI      URL     [本文引用: 1]

Xu Y X, Gao W W, Gao C.

A review on graphene-based electromagnetic functional materials: electromagnetic wave shielding and absorption

[J]. Adv. Funct. Mater., 2022, 32: 2204591

DOI      URL     [本文引用: 1]

Huang M Q, Wang L, Pei K, et al.

Multidimension-controllable synthesis of MOF-derived Co@N-doped carbon composite with magnetic-dielectric synergy toward strong microwave absorption

[J]. Small, 2020, 16: 2000158

DOI      URL     [本文引用: 1]

Zhao B, Hamidinejad M, Wang S, et al.

Advances in electromagnetic shielding properties of composite foams

[J]. J. Mater. Chem., 2021, 9A: 8896

[本文引用: 3]

Wang L, Zhang J, Wang M, et al.

Hollow porous Fe2O3 microspheres wrapped by reduced graphene oxides with high-performance microwave absorption

[J]. J. Mater. Chem., 2019, 7C: 11167

[本文引用: 1]

Cao W Q, Wang X X, Yuan J, et al.

Temperature dependent microwave absorption of ultrathin graphene composites

[J]. J. Mater. Chem., 2015, 3C: 10017

[本文引用: 1]

Zheng X L, Feng J, Zong Y, et al.

Hydrophobic graphene nanosheets decorated by monodispersed superparamagnetic Fe3O4 nanocrystals as synergistic electromagnetic wave absorbers

[J]. J. Mater. Chem., 2015, 3C: 4452

[本文引用: 3]

Wang L, Huang Y, Li C, et al.

Hierarchical graphene@Fe3O4 nanocluster@carbon@MnO2 nanosheet array composites: synthesis and microwave absorption performance

[J]. Phys. Chem. Chem. Phys., 2015, 17: 5878

DOI      PMID      [本文引用: 1]

The fabrication of novel hierarchical graphene@Fe3O4 nanocluster@carbon@MnO2 nanosheet array composites has been successfully carried out for the first time. The fabrication process involves the deposition of Fe3O4 nanoclusters on graphene's surface using a simple in situ hydrothermal method, subsequent introduction of carbon on the surface of graphene@Fe3O4 nanoclusters by combining the hydrothermal reaction and thermal treatment process, and finally formation of the hierarchical composites via a simple in situ redox replacement reaction between potassium permanganate (KMnO4) and carbon on the surface of graphene@Fe3O4 nanoclusters. Moreover, the microwave absorption properties of both graphene@Fe3O4 nanoclusters and hierarchical graphene@Fe3O4 nanocluster@carbon@MnO2 nanosheet array composites were investigated between 2 and 18 GHz microwave frequency bands. The electromagnetic data demonstrate that graphene@Fe3O4 nanocluster@carbon@MnO2 nanosheet array hierarchical composites exhibit significantly enhanced microwave absorption properties compared with graphene@Fe3O4 nanoclusters, which probably originate from the unique hierarchical structure and larger surface area.

Wang Y, Gao X, Wu X M, et al.

Facile design of 3D hierarchical NiFe2O4/N-GN/ZnO composite as a high performance electromagnetic wave absorber

[J]. Chem. Eng. J., 2019, 375: 121942

DOI      URL     [本文引用: 1]

Liu P B, Huang Y, Yan J, et al.

Construction of CuS nanoflakes vertically aligned on magnetically decorated graphene and their enhanced microwave absorption properties

[J]. ACS Appl. Mater. Interfaces, 2016, 8: 5536

DOI      URL     [本文引用: 1]

Yan F, Guo D, Zhang S, et al.

An ultra-small NiFe2O4 hollow particle/graphene hybrid: fabrication and electromagnetic wave absorption property

[J]. Nanoscale, 2018, 10: 2697

DOI      URL     [本文引用: 1]

Yan F, Zhang S, Zhang X, et al.

Growth of CoFe2O4 hollow nanoparticles on graphene sheets for high-performance electromagnetic wave absorbers

[J]. J. Mater. Chem., 2018, 6C: 12781

Yan F, Kang J Y, Zhang S, et al.

Enhanced electromagnetic wave absorption induced by void spaces in hollow nanoparticles

[J]. Nanoscale, 2018, 10: 18742

DOI      PMID      [本文引用: 1]

We developed a facile method for the growth of hollow structured NiCoO nanoparticles on a graphene sheet (NiCoO-h/G). The hollow NiCoO nanoparticles have an average diameter of approximately 10.0 nm and a shell thickness of merely 2.5 nm. The NiCoO-h/G hybrid exhibited excellent electromagnetic wave absorption with minimal reflection loss below -20 dB at absorber thickness ranging from 2.0 to 5.0 mm, outperforming the solid NiCoO nanoparticles on the graphene sheet. Remarkably, even for a thickness as small as 1.5 mm, the efficient absorption bandwidth and the minimal reflection loss of the hybrid can reach 2.6 GHz and -20.3 dB, respectively. Experimental results and theoretical calculations indicate that the void space in the hollow NiCoO nanoparticles plays a crucial role in the excellent electromagnetic wave absorption property, which greatly increases the dielectric loss and impedance matching characteristics. Our results demonstrate that growing the hollow nanoparticles on a graphene sheet is an efficient way to produce high-performance electromagnetic wave absorbers.

Zhang C, Wang B C, Xiang J Y, et al.

Microwave absorption properties of CoS2 nanocrystals embedded into reduced graphene oxide

[J]. ACS Appl. Mater. Interfaces, 2017, 9: 28868

DOI      URL     [本文引用: 3]

Li Q Q, Tan J, Wu Z C, et al.

Hierarchical magnetic-dielectric synergistic Co/CoO/RGO microspheres with excellent microwave absorption performance covering the whole X band

[J]. Carbon, 2023, 201: 150

DOI      URL     [本文引用: 1]

Zeng Q, Xiong X H, Chen P, et al.

Air@rGO€Fe3O4 microspheres with spongy shells: self-assembly and microwave absorption performance

[J]. J. Mater. Chem., 2016, 4C: 10518

[本文引用: 3]

Zeng Q, Chen P, Yu Q, et al.

Self-assembly of ternary hollow microspheres with strong wideband microwave absorption and controllable microwave absorption properties

[J]. Sci. Rep., 2017, 7: 8388

DOI      PMID     

In this study, we report a simple and efficient two-step method consisting of water-in-oil (W/O) emulsion technique and subsequent annealing process for synthesizing the hollow reduced graphene oxide microspheres embedded with Co nanoparticles (Air@rGO€Co). The microspheres showed good electromagnetic properties because of the coexistence of magnetic loss and dielectric loss to microwaves. The minimum reflection loss (RL) value of S reaches -68.1 dB at 13.8 GHz with a thickness of 2.2 mm, and the absorption bandwidth (lower than -10 dB) is 7.1 GHz covering from 10.9 GHz to 18.0 GHz. More interestingly, we can easily controll the microwave absorbing properties of the microspheres by changing the ratio of the two components in the composites. The excellent electromagnetic match at the corresponding resonance peaks for dielectric and magnetic loss play an important role in improving microwave absorption property. Our study provides a good potential method for preparation of lightweight microwave absorbing materials.

Zeng Q, Xu D W, Chen P, et al.

3D graphene-Ni microspheres with excellent microwave absorption and corrosion resistance properties

[J]. J. Mater. Sci. Mater. Electron., 2018, 29: 2421

DOI      URL     [本文引用: 1]

Li T, Zhi D D, Chen Y, et al.

Multiaxial electrospun generation of hollow graphene aerogel spheres for broadband high-performance microwave absorption

[J]. Nano Res., 2020, 13: 477

DOI      [本文引用: 3]

Cui Y H, Yang K, Wang J Q, et al.

Preparation of pleated RGO/MXene/Fe3O4 microsphere and its absorption properties for electromagnetic wave

[J]. Carbon, 2021, 172: 1

DOI      URL     [本文引用: 1]

Ye X C, Gao Q, He E Y, et al.

Graphene/carbonyl iron powder composite microspheres enhance electromagnetic absorption of 3D printing composites

[J]. J. Alloys Compd., 2023, 937: 168443

DOI      URL     [本文引用: 1]

Cai Y F, Cheng Y, Wang Z H, et al.

Facile and scalable preparation of ultralight cobalt@graphene aerogel microspheres with strong and wide bandwidth microwave absorption

[J]. Chem. Eng. J., 2023, 457: 141102

DOI      URL     [本文引用: 1]

Liu Z H, Fan Y H, Liu Z G, et al.

Wrinkled 3D MoS2/RGO/NC composite microspheres: optimal composition and microwave absorbing properties

[J]. Composites, 2022, 161A: 107119

[本文引用: 1]

Wang W T, Sun J W, Xu W Y, et al.

Development of wrinkled reduced graphene oxide wrapped polymer-derived carbon microspheres as viable microwave absorbents via a charge-driven self-assembly strategy

[J]. J. Colloid Interface Sci., 2023, 630: 34

DOI      URL     [本文引用: 1]

Tang P P, Deng Z M, Zhang Y, et al.

Tough, strong, and conductive graphene fibers by optimizing surface chemistry of graphene oxide precursor

[J]. Adv. Funct. Mater., 2022, 32: 2112156

DOI      URL     [本文引用: 3]

Hou Y L, Sheng Z Z, Fu C, et al.

Hygroscopic holey graphene aerogel fibers enable highly efficient moisture capture, heat allocation and microwave absorption

[J]. Nat Commun, 2022, 13: 1227

DOI      PMID      [本文引用: 1]

Aerogel fibers have been recognized as the rising star in the fields of thermal insulation and wearable textiles. Yet, the lack of functionalization in aerogel fibers limits their applications. Herein, we report hygroscopic holey graphene aerogel fibers (LiCl@HGAFs) with integrated functionalities of highly efficient moisture capture, heat allocation, and microwave absorption. LiCl@HGAFs realize the water sorption capacity over 4.15 g g, due to the high surface area and high water uptake kinetics. Moreover, the sorbent can be regenerated through both photo-thermal and electro-thermal approaches. Along with the water sorption and desorption, LiCl@HGAFs experience an efficient heat transfer process, with a heat storage capacity of 6.93 kJ g. The coefficient of performance in the heating and cooling mode can reach 1.72 and 0.70, respectively. Notably, with the entrapped water, LiCl@HGAFs exhibit broad microwave absorption with a bandwidth of 9.69 GHz, good impedance matching, and a high attenuation constant of 585. In light of these findings, the multifunctional LiCl@HGAFs open an avenue for applications in water harvest, heat allocation, and microwave absorption. This strategy also suggests the possibility to functionalize aerogel fibers towards even broader applications.© 2022. The Author(s).

Zheng X H, Tang J H, Wang P, et al.

Interfused core-shell heterogeneous graphene/MXene fiber aerogel for high-performance and durable electromagnetic interference shielding

[J]. J. Colloid Interface Sci., 2022, 628: 994

DOI      URL     [本文引用: 3]

Sheng A, Yang Y Q, Yan D X, et al.

Self-assembled reduced graphene oxide/nickel nanofibers with hierarchical core-shell structure for enhanced electromagnetic wave absorption

[J]. Carbon, 2020, 167: 530

DOI      URL     [本文引用: 1]

Chen Y W, Zhang H Y, Zeng G X.

Tunable and high performance electromagnetic absorber based on ultralight 3D graphene foams with aligned structure

[J]. Carbon, 2018, 140: 494

DOI      URL     [本文引用: 1]

Liu P B, Zhang Y Q, Yan J, et al.

Synthesis of lightweight N-doped graphene foams with open reticular structure for high-efficiency electromagnetic wave absorption

[J]. Chem. Eng. J., 2019, 368: 285

DOI      URL     [本文引用: 1]

Chen H H, Huang Z Y, Huang Y, et al.

Synergistically assembled MWCNT/graphene foam with highly efficient microwave absorption in both C and X bands

[J]. Carbon, 2017, 124: 506

DOI      URL     [本文引用: 1]

Zhang Y, Huang Y, Zhang T F, et al.

Broadband and tunable high-performance microwave absorption of an ultralight and highly compressible graphene foam

[J]. Adv. Mater., 2015, 27: 2049

DOI      URL     [本文引用: 3]

Xu D W, Liu J L, Chen P, et al.

In situ deposition of α-Co nanoparticles on three-dimensional nitrogen-doped porous graphene foams as microwave absorbers

[J]. J. Mater. Sci. Mater. Electron., 2019, 30: 13412

DOI      [本文引用: 3]

Xu D W, Yang S, Chen P, et al.

3D nitrogen-doped porous magnetic graphene foam-supported Ni nanocomposites with superior microwave absorption properties

[J]. J. Alloys Compd., 2019, 782: 600

DOI      URL    

Xu D W, Xiong X H, Chen P, et al.

Superior corrosion-resistant 3D porous magnetic graphene foam-ferrite nanocomposite with tunable electromagnetic wave absorption properties

[J]. J. Magn. Magn. Mater., 2019, 469: 428

DOI      URL     [本文引用: 1]

Huang Z Y, Chen H H, Huang Y, et al.

Ultra-broadband wide-angle terahertz absorption properties of 3D graphene foam

[J]. Adv. Funct. Mater., 2018, 28: 1704363

DOI      URL     [本文引用: 1]

Zhang M M, Fang X K, Zhang Y H, et al.

Ultralight reduced graphene oxide aerogels prepared by cation-assisted strategy for excellent electromagnetic wave absorption

[J]. Nanotechnology, 2020, 31: 275707

DOI      URL     [本文引用: 1]

Wang X Y, Lu Y K, Zhu T, et al.

CoFe2O4/N-doped reduced graphene oxide aerogels for high-performance microwave absorption

[J]. Chem. Eng. J., 2020, 388: 124317

DOI      URL     [本文引用: 1]

Zhao B, Li Y, Ji H Y, et al.

Lightweight graphene aerogels by decoration of 1D CoNi chains and CNTs to achieve ultra-wide microwave absorption

[J]. Carbon, 2021, 176: 411

DOI      URL     [本文引用: 3]

Zhao H B, Cheng J B, Zhu J Y, et al.

Ultralight CoNi/rGO aerogels toward excellent microwave absorption at ultrathin thickness

[J]. J. Mater. Chem., 2019, 7C: 441

[本文引用: 1]

Xu D W, Chen P, Chen G Z, et al.

Self-assembly synthesis and microwave absorption properties of magnetic functionalized graphene aerogels

[J]. Chin. Sci. Bull., 2022, 67: 437

[本文引用: 1]

徐东卫, 陈 平, 陈冠震 等.

磁功能化石墨烯气凝胶自组装合成及吸波性能

[J]. 科学通报, 2022, 67: 437

[本文引用: 1]

Xu D W, Liu J L, Chen P, et al.

In situ growth and pyrolysis synthesis of super-hydrophobic graphene aerogels embedded with ultrafine β-Co nanocrystals for microwave absorption

[J]. J. Mater. Chem., 2019, 7C: 3869

Xu D W, Yang S, Chen P, et al.

Synthesis of magnetic graphene aerogels for microwave absorption by in-situ pyrolysis

[J]. Carbon, 2019, 146: 301

DOI      URL     [本文引用: 1]

Cheng Z, Wang R F, Cao Y S, et al.

Intelligent off/on switchable microwave absorption performance of reduced graphene oxide/VO2 composite aerogel

[J]. Adv. Funct. Mater., 2022, 32: 2205160

DOI      URL     [本文引用: 3]

Zhang X J, Wang G S, Cao W Q, et al.

Fabrication of multi-functional PVDF/RGO composites via a simple thermal reduction process and their enhanced electromagnetic wave absorption and dielectric properties

[J]. RSC Adv., 2014, 4(38): 19594

DOI      URL     [本文引用: 1]

Ren F, Zhu G M, Xie J Q, et al.

Cyanate ester filled with graphene nanosheets and multi-walled carbon nanotubes as a microwave absorber

[J]. J. Polym. Res., 2015, 22(5): 89

DOI      URL     [本文引用: 1]

Chen J P, Jia H, Liu Z, et al.

Construction of C-Si heterojunction interface in SiC whisker/reduced graphene oxide aerogels for improving microwave absorption

[J]. Carbon, 2020, 164: 59

DOI      URL     [本文引用: 1]

Lv X J, Duan Y P, Chen G Q.

Electromagnetic wave absorption properties of cement-based composites filled with graphene nano-platelets and hollow glass microspheres

[J]. Constr. Build. Mater., 2018, 162: 280

DOI      URL     [本文引用: 1]

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