nickel ferrite ternary nanocomposites

nickel ferrite ternary nanocomposites

Accepted Manuscript Design and electromagnetic wave absorption properties of reduced graphene oxide/ multi-walled carbon nanotubes/nickel ferrite tern...

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Accepted Manuscript Design and electromagnetic wave absorption properties of reduced graphene oxide/ multi-walled carbon nanotubes/nickel ferrite ternary nanocomposites Yue Wu, Ruiwen Shu, Zhenyin Li, Changlian Guo, Gengyuan Zhang, Jiabin Zhang, Weijie Li PII:

S0925-8388(19)30147-1

DOI:

https://doi.org/10.1016/j.jallcom.2019.01.139

Reference:

JALCOM 49177

To appear in:

Journal of Alloys and Compounds

Received Date: 18 December 2018 Revised Date:

10 January 2019

Accepted Date: 11 January 2019

Please cite this article as: Y. Wu, R. Shu, Z. Li, C. Guo, G. Zhang, J. Zhang, W. Li, Design and electromagnetic wave absorption properties of reduced graphene oxide/multi-walled carbon nanotubes/ nickel ferrite ternary nanocomposites, Journal of Alloys and Compounds (2019), doi: https:// doi.org/10.1016/j.jallcom.2019.01.139. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

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Graphical Abstract

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Design and electromagnetic wave absorption properties of reduced

graphene

oxide/multi-walled

carbon

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nanotubes/nickel ferrite ternary nanocomposites

Yue Wu, Ruiwen Shu*, Zhenyin Li, Changlian Guo, Gengyuan Zhang,

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Jiabin Zhang, Weijie Li

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School of Chemical Engineering, Anhui University of Science and Technology, Huainan, 232001, People’s Republic of China

*Corresponding author:

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E-mail address: [email protected] (R. Shu).

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Abstract Herein, amphiphilic graphene oxide (GO) was used as the “surfactant” to directly disperse pristine multi-walled carbon nanotubes (MWCNTs) in aqueous dispersions and the reduced graphene oxide/multi-walled carbon nanotubes/nickel ferrite

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(RGO/MWCNTs/NiFe2O4) ternary nanocomposites were further synthesized by a facile one-pot hydrothermal strategy. The structure, compositions, micromorphology and electromagnetic parameters of the ternary nanocomposites were investigated by

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various analytical techniques. Experimental results revealed that the ternary nanocomposites exhibited the enhanced electromagnetic wave (EMW) absorption

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performance compared with the binary nanocomposite and single NiFe2O4. The minimum reflection loss (RLmin) reached -50.2 dB with a thin thickness of 1.4 mm and effective absorption bandwidth (EAB, RL ≤ -10 dB) was 5.0 GHz (13–18 GHz). Meanwhile, the EAB could reach 14.64 GHz (91.5% of 2–18 GHz) by facilely

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adjusting the coating thicknesses from 1 to 5 mm. Furthermore, the possible EMW absorption mechanism was proposed. Besides, the EMW absorption performance was highly tunable by changing the additive amounts of MWCNTs, filler loading ratios

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and coating thicknesses. Our results could be helpful for designing and developing

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novel graphene-based high-performance EMW absorbers.

Keywords: Nanocomposites; Electromagnetic wave absorption; Graphene; Carbon nanotubes; Nickel ferrite

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1. Introduction Electromagnetic pollution has becoming an increasingly serious problem originated from the extensive use of electronic equipment and devices. Therefore, the electromagnetic wave (EMW) absorbing materials gain significant attention in the

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field of functional materials [1-6]. However, it is still a great challenge for developing novel EMW absorbing materials that simultaneously satisfy the following requirements, such as broad frequency, strong absorption, light weight and thin

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thickness [1,4-6].

As a popular kind of magnetic ferrites, nickel ferrite (NiFe2O4) shows the

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characteristics of moderate saturation magnetization, well chemical stability and low cost, thus it has potential applications in the field of EMW absorption [1,7-10]. However, the drawbacks like high density, narrow frequency bandwidth and inferior impedance matching, which limit the practical applications of NiFe2O4 for EMW

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absorption [1].

Reduced graphene oxide (RGO) has been regarded as a promising candidate for EMW absorption due to its unique plane structure, low density, residual functional and

defect

polarization

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groups

relaxation

[1,11-26].

Generally,

the

two

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electromagnetic principles of maximum attenuation and impedance matching should be carefully regulated for designing an ideal EMW absorber. Recent investigations revealed that the complexation of RGO with magnetic ferrites for fabricating RGO-based hybrid composites could be a useful way to further enhance the EMW absorption performance of RGO [1,17,27-36]. For instance, Zhang et al. synthesized the nanohybrids of NiFe2O4/RGO by a confined growth approach and found that the minimum reflection loss (RLmin) reached -58 dB and effective absorption bandwidth (EAB, RL ≤ -10 dB) was 4.08 GHz at a thickness of 2.7 mm [1]. Liu et al. prepared

ACCEPTED MANUSCRIPT the hierarchical CoFe2O4/RGO nanocomposites by a solvothermal method. The binary nanocomposites exhibited the RLmin of -57.7 dB and EAB of 5.8 GHz at a thickness of 2.8 mm [17]. However, it is still hard to develop the high-efficiency EMW absorbers of RGO-based hybrid composites by a facile strategy with a thin coating thickness (<

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2 mm).

Recently, multi-walled carbon nanotubes (MWCNTs) have been extensively reported as the EMW absorbers due to their unique tubular structure, high aspect ratio

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and good electrical conductivity [37-42]. However, the poor aqueous solution dispersion of MWCNTs because of their hydrophobic nature limits the practical

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applications as the EMW absorbers [43]. It is well documented that the surface functionalization of MWCNTs by the reflux treatments in the concentrated nitric acid could effectively improve the aqueous solution dispersion of MWCNTs [37,39-41]. It should also be noted that although the solution dispersion improved after the acid

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treatment, the electronic structure of MWCNTs has been greatly damaged [43,44]. The C–C interfacial layers in the RGO/MWCNTs composites with mismatched electronic structures, which reduce the electronic transmission efficiency and thus

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further influence the transmission of EMWs in the materials [44].

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Recent studies demonstrated that the amphiphilic graphene oxide (GO) could be used as the “surfactant” to directly disperse the pristine MWCNTs without any additives to form stable aqueous GO/MWCNTs dispersion [43]. Thus, the contradictions of poor aqueous solution dispersion and electronic structure damage of MWCNTs could be well solved by the direct dispersion of pristine MWCNTs in amphiphilic GO aqueous dispersion and further in-situ reduction of GO. Based on the above discussion, it is believed that the hybridization of magnetic NiFe2O4,

ACCEPTED MANUSCRIPT conductive MWCNTs with RGO may be a feasible way to enhance the electromagnetic attenuation capacity and optimize the impedance matching. Herein, we reported a facile strategy to synthesis the RGO/MWCNTs/NiFe2O4 ternary nanocomposites and further explored the effect of additive amounts of

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MWCNTs on their EMW absorption performance. Furthermore, the relationship between microstructure and EMW absorption properties was systematically explored. The as-prepared ternary nanocomposites exhibited excellent EMW absorption

2. Experimental The

detailed

synthesis

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possible EMW absorption mechanism was proposed.

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performance with wide bandwidth, strong absorption and thin thickness. Besides, the

procedures

and

characterization

of

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RGO/MWCNTs/NiFe2O4 ternary nanocomposites were described in the electronic supplementary materials.

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3. Results and discussion

The synthesis process of RGO/MWCNTs/NiFe2O4 ternary nanocomposites is

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schematically illustrated, as shown in Fig. 1. The ternary nanocomposites were gained via a facile self-assembly of GO and MWCNTs in aqueous dispersion and adsorption of Ni2+/Fe3+ by electrostatic interaction, and subsequent hydrothermal reaction. Thus, the GO was partially reduced into RGO, and NiFe2O4 nanoparticles were nucleated and grown in situ on the surface of RGO. As displayed in Fig. 2, the X-ray diffraction (XRD) patterns are well consistent with the standard profile of spinel NiFe2O4 (JCPDS No. 10-0325) in all the samples

ACCEPTED MANUSCRIPT [1,28,29,45]. The obvious diffraction peaks at 2θ = 30.5, 36.0, 43.6, 57.7 and 63.2o, which correspond to the (220), (311), (400), (511) and (440) crystal planes of NiFe2O4, respectively. Furthermore, the absence of (001) diffraction peak of graphite oxide (9.7o, as shown in Fig. S1) in the S1, S2 and S3, which suggests the reduction of GO

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to RGO during the hydrothermal process. Meanwhile, no diffraction peak of graphite (~ 26o, as shown in Fig. S1) can be observed in the hybrid nanocomposites, which indicates the agglomeration of RGO nanosheets remarkably suppressed by the loaded

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NiFe2O4 nanoparticles [29]. Besides, no diffraction peaks of MWCNTs appear in the S2 and S3, which may be ascribed to the low content of MWCNTs [46].

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The degree of graphitization in carbonaceous materials can be detected by Raman spectroscopy. As shown in Fig. 3, the hybrid nanocomposites present two prominent peaks at around 1600 cm-1 (G band) and 1335 cm-1 (D band), which denote the vibration of sp2 hybridization and sp3 defects, respectively [46,47]. ID/IG (the

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intensity ratio of D to G band) is generally used to characterize the disorder degree [46,47]. The ID/IG of S1 is equal to 1.286, which is much larger than that of GO (0.89, as shown in Fig. S2). The higher value of ID/IG signifies the existence of more defects

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and disorders in the S1 than that of GO. It can also be seen that the ID/IG increases

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from 1.269 (S2) to 1.291 (S3). However, the values of ID/IG for S2 and S3 are smaller than that of pristine MWCNTs (1.57, as shown in Fig. S2). Therefore, the ID/IG increases with the increase of the additive amounts of MWCNTs. Furthermore, the Raman scattering peaks appear at the low-wavenumbers range (100–1000 cm-1), which are in good accordance with the previous reports on NiFe2O4 particles [1,29,45]. Besides, the intensity of Raman scattering peaks of NiFe2O4 becomes weaker with the increase of the additive amounts of MWCNTs in the ternary nanocomposites. Microscopic morphology and structure of the as-prepared hybrid nanocomposites

ACCEPTED MANUSCRIPT were observed by the scanning electron microscopy (SEM). From Fig. 4(a) and (b), it is obvious that the NiFe2O4 particles present the irregular shapes with nanometer size. As shown in Fig. 4(c) and (d), the RGO exhibits the flake-like morphology and the nano-sized NiFe2O4 particles are deposited on the surface of RGO with small

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aggregation in the S1. As displayed in Fig. 4(e)−(h), the surface of RGO is loaded with numerous NiFe2O4 nanoparticles and twined with MWCNTs. Compared with the SEM images of the S2 and S3, it can be observed that more MWCNTs appear in the

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S3, which is in good accordance with the feeding ratio in the experimental section. Due to the one dimensional (1D) structure, large aspect ratio and high conductivity of

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the MWCNTs, the RGO/MWCNTs/NiFe2O4 ternary nanocomposites could build the conductive networks in the paraffin wax matrix for electrons hopping and migration [48,49]. According to the formula of micro-current network reported by Cao et al.[50], when the surface of RGO is loaded with NiFe2O4 nanoparticles and twined with

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MWCNTs, the NiFe2O4 can act as the electron-hoping bridges between neighboring RGO and MWCNTs, which contributes to the formation of micro-current networks, resulting in enhanced conduction loss compared with pure NiFe2O4 [50].

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Consequently, the local three dimensional (3D) conductive networks are formed in

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situ in the ternary nanocomposites of S2 and S3 (as shown by yellow dashed box in Fig. 4(f) and (h)) and the S3 shows more complete 3D networks than that of S2, which are beneficial to enhancing the conduction loss for attenuating the incident EMWs [51]. Fig. 4(i) displays the energy dispersive X-ray spectrum (EDS) pattern of S2, which reveals the existence of Ni, Fe, O and C elements. Fig. 5 displays the transmission electron microscopy (TEM) observations of S2. As depicted in Fig. 5(a)−(c), the RGO exhibits the flake-like and transparent profile, which suggests the few layers nature of RGO. Furthermore, the nano-sized NiFe2O4

ACCEPTED MANUSCRIPT particles are deposited on the twined structure of RGO/MWCNTs. High-resolution TEM image (HRTEM, as shown in Fig. 5(d)) reveals the inter-plane distance between fringes of 0.251 nm, which corresponds to the (311) plane of NiFe2O4. Fig. 5(e) clearly shows that the NiFe2O4 nanoparticles have a statistical average size of 12.41

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nm. As shown in Fig. S3, it is clear that the RGO sheets exhibit crumpled and rippled structure, which are twined with MWCNTs in the RGO/MWCNTs hybrid composite. Generally, the EMW absorption performance is closely related to the magnetic

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properties. Fig. 6 depicts the magnetic hysteresis loops of the four samples. It is obvious that the samples of NiFe2O4, S1, S2 and S3 present the typical ferromagnetic

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hysteresis behavior with the saturation magnetization (Ms) of 55.4, 50.0, 47.8 and 45.6 emu/g, respectively, which is beneficial for the magnetic loss of incident EMWs. Furthermore, the Ms decreases as the NiFe2O4 hybridization with RGO or MWCNTs. Besides, the S3 shows the smallest Ms among all the samples, which originates from

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the increase of non-magnetic MWCNTs in the S3.

To explore the influence of filler loading ratios on the EMW absorption properties, the electromagnetic measurements of S2 with three different filler loading

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ratios were performed. From Fig. S4, it can be seen that the S2 shows the optimal

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EMW absorption (RLmin of -39.2 dB and EAB of 4.5 GHz) for a filler loading ratio of 50 wt%. Therefore, the loading ratio of 50 wt% has been chosen to compare with the EMW absorption among all the samples in the following discussion. Fig. 7 depicts the frequency dependence of reflection loss (RL) with different

thicknesses for all the samples. From Fig. 7(a), it is clear that the RLmin of NiFe2O4 is larger than -5.0 dB, suggesting the poor EMW attenuation capacity. As shown in Fig. 7(b)–(d), the S1, S2 and S3 present the enhanced EMW attenuation compared with the NiFe2O4. To be specific, the S1 presents the RLmin of -24.4 dB and EAB of 4.8

ACCEPTED MANUSCRIPT GHz, the S3 shows the RLmin of -44.7 dB and EAB of 5.0 GHz, while the S2 exhibits the RLmin of -50.2 dB with a thickness of only 1.4 mm and EAB of 4.5 GHz. Moreover, the EAB of S2 could reach 14.64 GHz (91.5% of 2–18 GHz) by facilely adjusting the coating thicknesses from 1 to 5 mm, which spans the whole C, X and Ku

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bands. Consequently, the ternary nanocomposites (S2 and S3) demonstrate obviously enhanced EMW absorption performance compared with the binary nanocomposite (S1) and single NiFe2O4. Besides, the additive amounts of MWCNTs should be

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carefully controlled for the sake of obtaining excellent EMW absorption properties.

Fig. 8 shows the frequency-dependent electromagnetic parameters (ε', ε'', µ', µ'')

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and loss tangent. From Fig. 8(a), it is obvious that the ε' of S1–S3 decreases with the increase of frequency except slight fluctuations in the high-frequency range (12–18 GHz), and the S1 shows the largest ε'. To be specific, the ε' of S1, S2 and S3 decreases from 17.0 to 9.4, 14.8 to 6.5 and 14.5 to 7.1, respectively. However, the ε'

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of NiFe2O4 almost remains constant around 3.3. As displayed in Fig. 8(b), the ε'' of S1–S3 decreases with some fluctuations as the frequency increases from 2 to 16 GHz, while the NiFe2O4 almost keeps constant with a value of 0. Furthermore, both ε' and

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ε'' of S1 are larger than that of other samples almost in 2–18 GHz. Fig. 8(c) depicts

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the frequency-dependent µ'. For all samples, the values of µ' are in the range of 0.9– 1.3. However, the NiFe2O4 presents the largest µ' almost in 2–18 GHz. From Fig. 8(d), it can be found that the µ'' of all the samples are in the range of -0.1–0.5 and the NiFe2O4 exhibits the largest µ'' almost in 2–16 GHz. However, the sample of S1 exhibits an obvious peak value of 0.45 at 17.28 GHz, which suggests the strong EMW attenuation capacity. Electromagnetic attenuation loss including the magnetic loss tangent (tanδm =

ACCEPTED MANUSCRIPT µ''/µ') and dielectric loss tangent (tanδe = ε''/ε'), which significantly affects the EMW absorption properties of absorbers [46]. As displayed in Fig. 8(e), the S1, S2 and S3 exhibit much larger tanδe than that of the NiFe2O4, which indicates the enhanced dielectric loss capacity. Furthermore, the S1 shows the strongest dielectric loss in 2–

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16 GHz. Fig. 8(f) displays the frequency-dependent tanδm. In 2–14 GHz, no distinguished differences among all the samples can be observed. However, the S1 shows a prominent tanδm peak (0.49) at 17.28 GHz, which suggests the existence of

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significant magnetic loss.

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In the microwave frequency range (2–18 GHz), investigations demonstrated that only the exchange resonance, eddy current loss, and natural resonance were responsible for the magnetic loss [27,37]. Because the mean particle size of small NiFe2O4 nanoparticles (~12.41 nm, as depicted in Fig. 5(e)) is close to the exchange length (~10 nm) [37], which suggests the exchange resonance could play an important

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role in the magnetic loss. Generally, the permeability can be expressed by the following equation [27,37]:

µ '' ≈ 2πµ0 ( µ ' ) σ d 2 f / 3 2

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(1)

Herein σ (S/cm) and µ0 (H/m) are the conductivity and permeability in the vacuum,

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respectively. If the eddy current loss is the dominated mechanism of magnetic loss, the eddy current coefficient C0 (µ''(µ')-2f-1) should remain constant as the frequency changes [27,37]. From Fig. 9, it can be seen that the values of C0 of all the samples show obvious fluctuations in the high-frequency range of 8–18 GHz, which suggests the eddy current loss is not the dominated mechanism for magnetic loss. Besides, all the samples exhibit prominent peaks of C0 in the low-frequency range, suggesting the existence of significant natural resonance [27,37].

ACCEPTED MANUSCRIPT Generally, the two electromagnetic principles of maximum attenuation and impedance matching should be carefully regulated for designing an ideal EMW absorber [37]. The impedance matching (Z) can be defined as follows [52-56]:

Z in = Z0

µr   2π fd   tanh  j   µrε r  εr   c  

(2)

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Z=

If Z = 1, the input impedance will be equal to that of the free space, which indicates

which is desired for an ideal EMW absorber.

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the optimal impedance matching. Therefore, the value of Z is equal or close to 1,

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The attenuation constant (α) determines the electromagnetic loss capacity, which can be defined as the following equation [37,46,57,58]:

α =

2π f × ( µ'' ε '' - µ' ε ' ) + ( µ'' ε '' - µ' ε ' ) 2 + (ε ' µ'' + ε '' µ' ) 2 c

(3)

Fig. 10 depicts the frequency dependence of Z and α. From Fig. 10(a), it can be

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found that the Z values of NiFe2O4 are far less than 1 in 2–18 GHz, suggesting a bad impedance matching. The S1 shows larger Z values than that of the NiFe2O4 in 7–17 GHz, indicating the better impedance matching. Moreover, the S2 and S3 show the Z

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values much closer to 1 than S1, which suggests the improved impedance matching.

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Overall, the S2 exhibits the optimal impedance matching among all the samples. From Fig. 10(b), it can be seen that the NiFe2O4 presents the weak EMW attenuation capacity owing to the largest attenuation constant less than 40. However, the α of all the nanocomposites clearly enhances compared with NiFe2O4. Furthermore, the S1 shows the largest α values, which indicates the strongest EMW attenuation capacity. As discussed in Fig. 2, the GO could be reduced into RGO during the hydrothermal process, which leads to the enhanced conduction loss of S1 originated from the good conductivity of RGO [48-50]. The good conduction loss of RGO further contributes

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According to the quarter-wavelength matching theory (λ/4), the relationship between coating thickness (tm) and absorption peak frequency (fm) obeys the

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following equation [37,46,57,58]:

(4)

EMW attenuation [37,46].

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If tm and fm meet the equation (4), the phase cancellation effect will contribute to the

From Fig. 11(a), it is obvious that the RL peaks of S2 shift to the lower frequency as the tm increases. Fig. 11(b) shows the relationship between tm and fm of S2. The

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five-pointed stars stand for the experimental tm (denoted as tmexp). Remarkably, all the tmexp are well located at the λ/4 curve, which suggests that the λ/4 rule governs the relationship between tm and fm. Besides, the strongest RL peak of S2 (16.9 GHz and

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1.4 mm) is in good accordance with the optimal impedance matching (Z = 1), as

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shown in Fig. 11(c).

As shown in Fig. 12, the possible EMW absorption mechanism of

RGO/MWCNTs/NiFe2O4 ternary nanocomposites could be described as the following aspects. Firstly, the residual oxygen-containing functional groups and defects on the surface of RGO cause the charge asymmetric distributions, inducing the formation of dipoles. These dipoles could rotate toward the alternating electromagnetic field, converting electromagnetic energy into heat energy due to the relaxation loss [15,20,59-61]. Secondly, the multiply heterogeneous interfaces among NiFe2O4

ACCEPTED MANUSCRIPT nanoparticles, MWCNTs and RGO sheets could be considered as the capacitor-like structure [37,62]. According to the model proposed by Cao et al. [62], the capacitor-like structure at the interfaces could attenuate the power of incident EMWs by aligning the polar bonds or charges in the alternating electromagnetic field [62].

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Thirdly, the nano-sized NiFe2O4 particles could act as the polarization centers to enhance the interfacial polarization relaxation [40]. Lastly, according to the Cao's Electron-Hopping model [48,49], the electrons could absorb electromagnetic energy

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to migrate in RGO or MWCNTs, and then convert energy by colliding with the lattice [60]. Besides, electrons could absorb more electromagnetic energy to jump across the

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potential barriers at the site of clustered functional groups or contact site of neighboring RGO and MWCNTs. Then, more electrons hopping and conductivity of conductive network enhance, which convert more electromagnetic energy into heat energy [60,61].

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In this study, the EMW absorption properties of obtained hybrid nanocomposites were carefully compared with other reported graphene-based spinel ferrite composites for the sake of reducing the influence of density on the EMW absorption. Moreover,

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the specific RLmin proposed by Li et al. [63] was chosen for comparison. As depicted in Table 1, the ternary nanocomposite of S2 exhibits the optimal specific RLmin of

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-35.9 dB·mm-1, indicating the excellent EMW absorption performance.

4. Conclusions

In summary, we successfully synthesized the RGO/MWCNTs/NiFe2O4 ternary nanocomposites by a facile strategy. Results demonstrated that the ternary nanocomposites showed the enhanced EMW absorption performance compared with the binary nanocomposite and single NiFe2O4. Significantly, the superior EMW

ACCEPTED MANUSCRIPT absorption performance of ternary nanocomposites can be facilely controlled by changing the additive amounts of MWCNTs, filler loading ratios and coating thicknesses. Furthermore, the possible EMW absorption mechanism was explored and could be ascribed to the dipole polarization, interfacial polarization, dielectric

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relaxation, tunneling effect and induced currents, synergistic effect of dielectric loss, conduction loss and magnetic loss, balanced impedance matching and electromagnetic attenuation. Consequently, the obtained ternary nanocomposites could be used as the

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Acknowledgments

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high-efficiency EMW absorbers.

This work was financially supported by the National Natural Science Foundation of China (Grant No. 51507003), the Program of Innovation and Entrepreneurship for Undergraduates of Anhui Province (Grant No. 201710361261, 201710361280,

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201710361283), the Lift Engineering of Young Talents and Doctor’s Start-up Research Foundation of Anhui University of Science and Technology (Grant No.

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ZY537).

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Supplementary material

Supplementary data associated with this article can be seen in the attachment.

References

[1] Y. Zhang, X. Wang, M. Cao, Confinedly implanted NiFe2O4-rGO: Cluster tailoring and highly tunable electromagnetic properties for selective-frequency microwave absorption, Nano Res. 11 (2018) 1426-1436. [2] J. Yu, J. Yu, T. Ying, C. Cui, Y. Sun, X. Liu, The design and the preparation of

ACCEPTED MANUSCRIPT mesoporous Ag3PO4 nanorod/SrFe12O19 hexagonal nanoflake heterostructure for excellent microwave absorption, J. Alloys Compd. 775 (2019) 225-232. [3] Y. Zuo, J. Luo, M. Cheng, K. Zhang, R. Dong, Synthesis, characterization and enhanced electromagnetic properties of BaTiO3/NiFe2O4-decorated reduced

RI PT

graphene oxide nanosheets, J. Alloys Compd. 744 (2018) 310-320.

[4] J. Ma, J. Shu, W. Cao, M. Zhang, X. Wang, J. Yuan, M. Cao, A green fabrication and variable temperature electromagnetic properties for thermal stable

Compos. Part B-Eng. 166 (2019) 187-195.

SC

microwave absorption towards flower-like [email protected]/SiO2 composites,

M AN U

[5] M. Cao, Y. Cai, P. He, J. Shu, W. Cao, J. Yuan, 2D MXenes: Electromagnetic property for microwave absorption and electromagnetic interference shielding, Chem. Eng. J. 359 (2019) 1265-1302.

[6] X. Wang, J. Shu, X. He, M. Zhang, X. Wang, C. Gao, J. Yuan, M. Cao, Green

TE D

Approach to Conductive PEDOT:PSS Decorating Magnetic-Graphene to Recover Conductivity for Highly Efficient Absorption, ACS Sustainable Chem. Eng. 6 (2018) 14017-14025.

EP

[7] X. Gu, W. Zhu, C. Jia, R. Zhao, W. Schmidt, Y. Wang, Synthesis and microwave

AC C

absorbing properties of highly ordered mesoporous crystalline NiFe2O4, Chem. Commun. 47 (2011) 5337-5339.

[8] W. Zhu, L. Wang, R. Zhao, J. Ren, G. Lu, Y. Wang, Electromagnetic and microwave-absorbing properties of magnetic nickel ferrite nanocrystals, Nanoscale 3 (2011) 2862-2864. [9] P. Liu, Y. Huang, J. Yan, Y. Yang, Y. Zhao, Construction of CuS Nanoflakes Vertically Aligned on Magnetically Decorated Graphene and Their Enhanced Microwave Absorption Properties, ACS Appl. Mater. Interfaces 8 (2016)

ACCEPTED MANUSCRIPT 5536-5546. [10] J. Zhang, R. Shu, C. Guo, R. Sun, Y. Chen, J. Yuan, Fabrication of nickel ferrite microspheres decorated multi-walled carbon nanotubes hybrid composites with enhanced electromagnetic wave absorption properties, J. Alloys Compd. 784

RI PT

(2019) 422-430.

[11] H. Zhao, X. Han, Z. Li, D. Liu, Y. Wang, Y. Wang, W. Zhou, Y. Du, Reduced graphene oxide decorated with carbon nanopolyhedrons as an efficient and

SC

lightweight microwave absorber, J. Colloid Interface Sci. 528 (2018) 174-183.

[12] Z. Wang, P. Zhao, D. He, Y. Cheng, L. Liao, S. Li, Y. Luo, Z. Peng, P. Li, Cerium

M AN U

oxide immobilized reduced graphene oxide hybrids with excellent microwave absorbing performance, Phys. Chem. Chem. Phys. 20 (2018) 14155-14165. [13] S. Gao, Q. Wang, Y. Lin, H. Yang, L. Wang, Flower-like Bi0.9La0.1FeO3 microspheres modified by reduced graphene oxide as a thin and strong

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electromagnetic wave absorber, J. Alloys Compd. 781 (2019) 723-733. [14] X. Wang, T. Ma, J. Shu, M. Cao, Confinedly tailoring Fe3O4 clusters-NG to tune electromagnetic parameters and microwave absorption with broadened

EP

bandwidth, Chem. Eng. J. 332 (2018) 321-330.

AC C

[15] R. Shu, G. Zhang, J. Zhang, X. Wang, M. Wang, Y. Gan, J. Shi, J. He, Fabrication of reduced graphene oxide/multi-walled carbon nanotubes/zinc ferrite hybrid composites as high-performance microwave absorbers, J. Alloys Compd. 736 (2018) 1-11.

[16] F. Meng, H. Wang, F. Huang, Y. Guo, Z. Wang, D. Hui, Z. Zhou, Graphene-based microwave absorbing composites: A review and prospective, Compos. Part B-Eng. 137 (2018) 260-277. [17] Y. Liu, Z. Chen, Y. Zhang, R. Feng, X. Chen, C. Xiong, L. Dong, Broadband and

ACCEPTED MANUSCRIPT Lightweight Microwave Absorber Constructed by in Situ Growth of Hierarchical CoFe2O4/Reduced Graphene Oxide Porous Nanocomposites, ACS Appl. Mater. Interfaces 10 (2018) 13860-13868. [18] M. Cao, C. Han, X. Wang, M. Zhang, Y. Zhang, J. Shu, H. Yang, X. Fang, J.

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Yuan, Graphene nanohybrids: excellent electromagnetic properties for the absorbing and shielding of electromagnetic waves, J. Mater. Chem. C 6 (2018) 4586-4602.

SC

[19] H. Lv, Y. Guo, Z. Yang, Y. Cheng, L.P. Wang, B. Zhang, Y. Zhao, Z.J. Xu, G. Ji, A brief introduction to the fabrication and synthesis of graphene based

Chem. C 5 (2017) 491-512.

M AN U

composites for the realization of electromagnetic absorbing materials, J. Mater.

[20] C. Wang, X. Han, P. Xu, X. Zhang, Y. Du, S. Hu, J. Wang, X. Wang, The electromagnetic property of chemically reduced graphene oxide and its

072906.

TE D

application as microwave absorbing material, Appl. Phys. Lett. 98 (2011)

[21] H. Chen, S. Bai, S. Li, F. Huang, Y. Lu, L. Wang, H. Zhang, Facile synthesis

EP

RGO/MnOx composite aerogel

as

high-efficient

electromagnetic

wave

AC C

absorbents, J. Alloys Compd. 773 (2019) 980-987. [22] P. Liu, M. Yang, S. Zhou, Y. Huang, Y. Zhu, Hierarchical shell-core structures of concave spherical NiO [email protected] for high performance supercapacitor electrodes, Electrochim. Acta 294 (2019) 383-390.

[23] P. Liu, J. Yan, X. Gao, Y. Huang, Y. Zhang, Construction of layer-by-layer sandwiched graphene/polyaniline nanorods/carbon nanotubes heterostructures for high performance supercapacitors, Electrochim. Acta 272 (2018) 77-87. [24] J. Zhang, R. Shu, Y. Ma, X. Tang, G. Zhang, Iron ions doping enhanced

ACCEPTED MANUSCRIPT electromagnetic wave absorption properties of tin dioxide/reduced graphene oxide nanocomposites, J. Alloys Compd. 777 (2019) 1115-1123. [25] G. Zhang, R. Shu, Y. Xie, H. Xia, Y. Gan, J. Shi, J. He, Cubic MnFe2O4 particles decorated reduced graphene oxide with excellent microwave absorption

RI PT

properties, Mater. Lett. 231 (2018) 209-212.

[26] P. Liu, Y. Huang, J. Yan, Y. Zhao, Magnetic [email protected]@porous TiO2 ternary composites for high-performance electromagnetic wave absorption, J.

SC

Mater. Chem. C 4 (2016) 6362-6370.

[27] S. Wang, Y. Zhao, H. Xue, J. Xie, C. Feng, H. Li, D. Shi, S. Muhammad, Q. Jiao,

M AN U

Preparation of flower-like [email protected] composites and their microwave absorbing properties, Mater. Lett. 223 (2018) 186-189.

[28] F. Yan, D. Guo, S. Zhang, C. Li, C. Zhu, X. Zhang, Y.J. Chen, Ultra-small NiFe2O4 hollow particle/graphene hybrid: fabrication and electromagnetic wave

TE D

absorption property, Nanoscale 10 (2018) 2697-2703.

[29] J. He, X. Wang, Y. Zhang, M. Cao, Small magnetic nanoparticles decorating reduced graphene oxides to tune the electromagnetic attenuation capacity, J.

EP

Mater. Chem. C 4 (2016) 7130-7140.

AC C

[30] R. Shu, G. Zhang, J. Zhang, X. Wang, M. Wang, Y. Gan, J. Shi, J. He, Synthesis and high-performance microwave absorption of reduced graphene oxide/zinc ferrite hybrid nanocomposite, Mater. Lett. 215 (2018) 229-232.

[31] P. Liu, Z. Yao, J. Zhou, Z. Yang, L.B. Kong, Small magnetic Co-doped NiZn ferrite/graphene nanocomposites and their dual-region microwave absorption performance, J. Mater. Chem. C 4 (2016) 9738-9749. [32] N. Zhang, Y. Huang, M. Zong, X. Ding, S. Li, M. Wang, Synthesis of ZnS quantum dots and CoFe2O4 nanoparticles co-loaded with graphene nanosheets as

ACCEPTED MANUSCRIPT an efficient broad band EM wave absorber, Chem. Eng. J. 308 (2017) 214-221. [33] Z. Yang, Y. Wan, G. Xiong, D. Li, Q. Li, C. Ma, R. Guo, H. Luo, Facile synthesis of ZnFe2O4/reduced graphene oxide nanohybrids for enhanced microwave absorption properties, Mater. Res. Bull. 61 (2015) 292-297.

RI PT

[34] X. Li, J. Feng, Y. Du, J. Bai, H. Fan, H. Zhang, Y. Peng, F. Li, One-pot synthesis of CoFe2O4/graphene oxide hybrids and their conversion into FeCo/graphene hybrids for lightweight and highly efficient microwave absorber, J. Mater. Chem.

SC

A 3 (2015) 5535-5546.

[35] X. Zhang, G.Wang, W. Cao, Y. Wei, J. Liang, L. Guo, M. Cao, Enhanced

M AN U

microwave absorption property of reduced graphene oxide (RGO)-MnFe2O4 nanocomposites and polyvinylidene fluoride, ACS Appl. Mater. Interfaces 6 (2014) 7471-7478.

[36] Y. Wang, X. Gao, X. Wu, W. Zhang, Q. Wang, C. Luo, Hierarchical

TE D

[email protected]@CuS composite: Strong absorption and wide-frequency absorption properties, Ceram. Int. 44 (2018) 9816-9822. [37] R. Shu, G. Zhang, X. Wang, X. Gao, M. Wang, Y. Gan, J. Shi, J. He, Fabrication

EP

of 3D net-like MWCNTs/ZnFe2O4 hybrid composites as high-performance

AC C

electromagnetic wave absorbers, Chem. Eng. J. 337 (2018) 242-255. [38] L. Zhu, X. Zeng, M. Chen, R. Yu, Controllable permittivity in 3D Fe3O4/CNTs network for remarkable microwave absorption performances, RSC Adv. 7 (2017) 26801-26808.

[39] B. Yang, Y. Wu, X. Li, R. Yu, Surface-oxidized FeCo/carbon nanotubes nanorods for lightweight and efficient microwave absorbers, Mater. Design 136 (2017) 13-22. [40] L. Lin, H. Xing, R. Shu, L. Wang, X. Ji, D. Tan, Y. Gan, Preparation and

ACCEPTED MANUSCRIPT microwave absorption properties of multi-walled carbon nanotubes decorated with Ni-doped SnO2 nanocrystals, RSC Adv. 5 (2015) 94539-94550. [41] M. Lu, W. Cao, H. Shi, X. Fang, J. Yang, Z. Hou, H. Jin, W. Wang, J. Yuan, M. Cao, Multi-wall carbon nanotubes decorated with ZnO nanocrystals: mild

RI PT

solution-process synthesis and highly efficient microwave absorption properties at elevated temperature, J. Mater. Chem. A 2 (2014) 10540-10547.

[42] L. Wang, Y. Huang, C. Li, J. Chen, X. Sun, A facile one-pot method to synthesize

SC

a three-dimensional [email protected] nanotube composite as a high-efficiency microwave absorber, Phys. Chem. Chem. Phys. 17 (2015) 2228-2234.

M AN U

[43] B. You, L. Wang, L. Yao, J. Yang, Three dimensional N-doped graphene–CNT networks for supercapacitor, Chem. Commun. 49 (2013) 5016-5018. [44] N. Zhou, Q. An, Z. Xiao, S. Zhai, Z. Shi, Solvothermal synthesis of three-dimensional, Fe2O3 NPs-embedded CNT/N-doped graphene composites

45156-45169.

TE D

with excellent microwave absorption performance, RSC Adv. 7 (2017)

[45] M. Fu, Q. Jiao, Y. Zhao, Preparation of NiFe2O4 nanorod–graphene composites

EP

via an ionic liquid assisted one-step hydrothermal approach and their microwave

AC C

absorbing properties, J. Mater. Chem. A 1 (2013) 5577-5586. [46] R. Shu, W. Li, X. Zhou, D. Tian, G. Zhang, Y. Gan, J. Shi, J. He, Facile preparation and microwave absorption properties of RGO/MWCNTs/ZnFe2O4 hybrid nanocomposites, J. Alloys Compd. 743 (2018) 163-174.

[47] H. Zhang, M. Hong, P. Chen, A. Xie, Y. Shen, 3D and ternary rGO/MCNTs/Fe3O4 composite hydrogels: synthesis, characterization and their electromagnetic wave absorption properties, J. Alloys Compd. 665 (2016) 381-387.

ACCEPTED MANUSCRIPT [48] W. Song, M. Cao, Z. Hou, X. Fang, X. Shi, J. Yuan, High dielectric loss and its monotonic

dependence

of

conducting-dominated

multiwalled

carbon

nanotubes/silica nanocomposite on temperature ranging from 373 to 873 K in X-band, Appl. Phys. Lett. 94 (2009) 233110.

RI PT

[49] M. Cao, W. Song, Z. Hou, B. Wen, J. Yuan, The effects of temperature and frequency on the dielectric properties, electromagnetic interference shielding and microwave-absorption of short carbon fiber/silica composites, Carbon 48 (2010)

SC

788-796.

[50] B. Wen, M. Cao, Z. Hou, W. Song, L. Zhang, M. Lu, H. Jin, X. Fang, W. Wang, J. Temperature

dependent

microwave

attenuation

M AN U

Yuan,

behavior

for

carbon-nanotube/silica composites, Carbon 65 (2013) 124-139. [51] J. Liu, H. Feng, X. Wang, D. Qian, J. Jiang, J. Li, S. Peng, M. Deng, Y. Liu, Self-assembly of nano/micro-structured Fe3O4 microspheres among 3D

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rGO/CNTs hierarchical networks with superior lithium storage performances, Nanotechnology 25 (2014) 225401.

[52] J. Feng, Y. Zong, Y. Sun, Y. Zhang, X. Yang, G. Long, Y. Wang, X. Li, X. Zheng,

EP

Optimization of porous FeNi3/N-GN composites with superior microwave

AC C

absorption performance, Chem. Eng. J. 345 (2018) 441-451. [53] W. Liu, Q. Shao, G. Ji, X. Liang, Y. Cheng, B. Quan, Y. Du, Metal– organic-frameworks derived porous carbon-wrapped Ni composites with optimized impedance matching as excellent lightweight electromagnetic wave absorber, Chem. Eng. J. 313 (2017) 734-744. [54] D. Li, B. Zhang, W. Liu, X. Liang, G. Ji, Tailoring the input impedance of FeCo/C composites with efficient broadband absorption, Dalton Trans. 46 (2017) 14926-14933.

ACCEPTED MANUSCRIPT [55] Y. Wang, X. Wu, W. Zhang, C. Luo, J. Li, Y. Wang, Fabrication of flower-like Ni0.5Co0.5(OH)[email protected] and its enhanced microwave absorption performances, Mater. Res. Bull. 98 (2018) 59-63. [56] K. Zhang, Q. Zhang, X. Gao, X. Chen, Y. Wang, W. Li, J. Wu, Effect of

RI PT

absorbers' composition on the microwave absorbing performance of hollow Fe3O4 nanoparticles decorated CNTs/graphene/C composites, J. Alloys Compd. 748 (2018) 706-716.

Solvothermal

synthesis

of

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[57] Z. Li, X. Li, Y. Zong, G. Tan, Y. Sun, Y. Lan, M. He, Z. Ren, X. Zheng, nitrogen-doped

graphene

decorated

by

M AN U

superparamagnetic Fe3O4 nanoparticles and their applications as enhanced synergistic microwave absorbers, Carbon 115 (2017) 493-502. [58] B. Quan, G. Xu, D. Li, W. Liu, G. Ji, Y. Du, Incorporation of dielectric constituents to construct ternary heterojunction structures for high-efficiency

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electromagnetic response, J. Colloid Interface Sci. 498 (2017) 161-169. [59] H. Xing, Z. Liu, L. Lin, L. Wang, D. Tan, Y. Gan, X. Ji, G. Xu, Excellent microwave absorption properties of Fe ion-doped SnO2/multi-walled carbon

EP

nanotube composites, RSC Adv. 6 (2016) 41656-41664.

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[60] M. Cao, X. Wang, W. Cao, X. Fang, B. Wen, J. Yuan, Thermally Driven Transport and Relaxation Switching Self-Powered Electromagnetic Energy Conversion, Small 14 (2018) 1800987.

[61] W. Cao, X. Wang, J. Yuan, W. Wang, M. Cao, Temperature dependent microwave absorption of ultrathin graphene composites, J. Mater. Chem. C 3 (2015) 10017-10022. [62] M.S. Cao, J. Yang, W.L. Song, D.Q. Zhang, B. Wen, H.B. Jin, Z.L. Hou, J. Yuan, Ferroferric oxide/multiwalled carbon nanotube vs polyaniline/ferroferric

ACCEPTED MANUSCRIPT oxide/multiwalled carbon nanotube multiheterostructures for highly effective microwave absorption, ACS Appl. Mater. Interfaces 4 (2012) 6949-6956. [63] N. Li, G.W. Huang, Y.Q. Li, H.M. Xiao, Q.P. Feng, N. Hu, S.Y. Fu, Enhanced Microwave Absorption Performance of Coated Carbon Nanotubes by Optimizing

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the Fe3O4 Nanocoating Structure, ACS Appl. Mater. Interfaces 9 (2017) 2973-2983.

Figure Captions

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Fig. 1. Schematic illustration of the synthesis process of RGO/MWCNTs/NiFe2O4 ternary nanocomposites.

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Fig. 2. XRD patterns of the samples of NiFe2O4, S1, S2 and S3.

Fig. 3. Raman spectra of the samples of NiFe2O4, S1, S2 and S3. Fig. 4. SEM images with different magnifications: (a)−(b) of NiFe2O4, (c)−(d) of S1, (e)−(f) of S2 and (g)−(h) of S3; (i) EDS pattern of S2.

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Fig. 5. TEM images with different magnifications (a)−(c), HRTEM image (d), particle size distribution histogram of NiFe2O4 nanoparticles (e) of S2. Fig. 6. Magnetic hysteresis loops of the samples of NiFe2O4, S1, S2 and S3 at room

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temperature. Inset: the magnified magnetization curves at the low field.

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Fig. 7. Frequency dependence of reflection loss with different thicknesses: (a) NiFe2O4, (b) S1, (c) S2 and (d) S3. Fig. 8. Frequency dependence of (a) ε', (b) ε'', (c) µ', (d) µ'', (e) tanδe and (f) tanδm for the samples of NiFe2O4, S1, S2 and S3. Fig. 9. Frequency dependence of the eddy current coefficient (C0) for the samples of NiFe2O4, S1, S2 and S3. Fig. 10. Frequency dependence of (a) impedance matching (Z) for the thickness of 1.4 mm and (b) attenuation constant (α) for the samples of NiFe2O4, S1, S2 and S3.

ACCEPTED MANUSCRIPT Fig. 11. (a) Frequency-dependent reflection loss, (b) simulations of the tm versus fm under the λ/4 model and (c) impedance matching (Z) as a function of frequency for the sample of S2 with different thicknesses. Fig. 12. Schematic illustration of the possible EMW absorption mechanism for the

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RGO/MWCNTs/NiFe2O4 ternary nanocomposites.

Table Caption

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Table 1. Typical graphene-based spinel ferrite hybrid composites as the EMW

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absorbers reported in this work and the recent literature.

ACCEPTED MANUSCRIPT Table 1. Typical graphene-based spinel ferrite hybrid composites as the EMW absorbers reported in this work and the recent literature. Filler

Matrix

Loading ratio (wt%)

Thickness (mm)

Specific RLmin (dB·mm-1)

RGO/MWCNTs/NiFe2O4 hybrid nanocomposite (S2)

wax

50

1.4

-50.2

-35.9

RGO/MWCNTs/NiFe2O4 hybrid nanocomposite (S3)

wax

50

1.6

-44.7

-27.9

5.0

This work

NiFe2O4 clusters/rGO

wax

/

2.7

-58

-21.5

/

[1]

wax

70

1.8

-53.6

-29.8

~5.0

[9]

RGO/MWCNTs/ZnFe2O4 hybrid composite

wax

50

1.0

-22.2

-22.2

2.3

[10]

CoFe2O4/rGO porous

wax

50

2.8

-57.7

-20.6

5.8

[12]

wax

45

2.0

-42

-21

~4.6

[17]

wax

15

3.5

-40.9

-11.7

2.8

[18]

wax

70

5.0

-42

-8.4

5.3

[19]

nanocomposites Flower-like [email protected] NiFe2O4 hollow particle/graphene hybrid NiFe2O4/r-GO RGO/ZnFe2O4

wax

-41.1

-16.4

3.2

[20]

40

3.1

-53.5

-17.3

4.8

[21]

30

1.6

-29.3

-18.3

2.6

[23]

5

3.0

-29

-9.7

4.88

[25]

/

/

3.0

-29.1

-9.7

3.47

[26]

wax

60

2.0

-29.2

-14.6

4.4

[36]

wax

20

1.9

-54.4

-28.6

3.2

[44]

wax

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wax

nanohybrids RGO/MnFe2O4

PVDF

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nanocomposites

3D CNTs/[email protected]

This work

2.5

ene nanocomposites ZnFe2O4/RGO

4.5

Reference

50

hybrid nanocomposite Co0.2Ni0.4Zn0.4Fe2O4/graph

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nanocomposites

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doped graphene

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nanocomposite Fe3O4 clusters-nitrogen

EAB (GHz)

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RLmin (dB)

composite aerogels NiFe2O4 nanorod–

graphene composites

Fe3O4/CNTs/graphene/C composites

Notes: Polyvinylidene fluoride was denoted as PVDF. GNS denoted the graphene nanosheets. Specific RLmin denoted the minimum reflection loss per thickness. EAB denoted the effective absorption bandwidth.

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ternary nanocomposites.

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Fig. 1. Schematic illustration of the synthesis process of RGO/MWCNTs/NiFe2O4

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(a) 1.2

0.8 0.6

d = 1.4 mm

0.4

NiFe2O4 S1 S2 S3

0.2 0.0 2

4

6

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12

14

(b) 350

S1 S2 S3

250

α

200 150

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NiFe2O4

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Z = |Zin/Z0|

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6

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Fig. 10. Frequency dependence of (a) impedance matching (Z) for the thickness of 1.4

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mm and (b) attenuation constant (α) for the samples of NiFe2O4, S1, S2 and S3.

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(a) 0

d / mm 1.0 1.4 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 sim tm =λ/4 exp tm =λ/4

RL (dB)

-10 -20 -30

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-40 -50

(b) 9

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tm (mm)

8

3 2 1

(c) 1.2 0.8

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Z = |Zin/Z0|

1.0

d / mm 1.0 1.4 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 8 10 12 14 16 18 20 22 24

0.6 0.4

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Frequency (GHz)

Fig. 11. (a) Frequency-dependent reflection loss, (b) simulations of the tm versus fm under the λ/4 model and (c) impedance matching (Z) as a function of frequency for the sample of S2 with different thicknesses.

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Fig. 12. Schematic illustration of the possible EMW absorption mechanism for the

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RGO/MWCNTs/NiFe2O4 ternary nanocomposites.

(440)

(511)

(400)

(311)

Intensity (a.u.)

(220)

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40

50

2θ ( ) o

60

70

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JCPDS (NO. 10-0325)

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Fig. 2. XRD patterns of the samples of NiFe2O4, S1, S2 and S3.

80

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ID/IG=1.291

S3

ID/IG=1.269

S2

ID/IG=1.286

S1

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Intensity (a.u.)

D G

NiFe2O4

0

1000

2000

3000

4000

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Raman shift (cm )

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Fig. 3. Raman spectra of the samples of NiFe2O4, S1, S2 and S3.

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Fig. 4. SEM images with different magnifications: (a)−(b) of NiFe2O4, (c)−(d) of S1, (e)−(f) of S2 and (g)−(h) of S3; (i) EDS pattern of S2.

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Fig. 5. TEM images with different magnifications (a)−(c), HRTEM image (d), particle size distribution histogram of NiFe2O4 nanoparticles (e) of S2.

ACCEPTED MANUSCRIPT 60 M / (emu/g)

10 0 -10 -20 -100

-50

0

50

100

H / Oe

0

NiFe2O4

-30

S1 S2 S3

-60 -30000 -20000 -10000

0

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M / (emu/g)

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10000 20000 30000

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Fig. 6. Magnetic hysteresis loops of the samples of NiFe2O4, S1, S2 and S3 at room

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temperature. Inset: the magnified magnetization curves at the low field.

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-1 d / mm 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

-2 -3 -4 -5 2

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S1 d / mm 1.0 1.4 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

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C band X band

Ku band

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S3

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d / mm 1.0 1.4 1.5 1.6 2.0 2.5 3.0 3.5 4.0 4.5 5.0

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d / mm 1.0 1.4 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0

(d) 0

Reflection Loss (dB)

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NiFe2O4

Reflection Loss (dB)

Reflection Loss (dB)

(a) 0

-40 -50

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Fig. 7. Frequency dependence of reflection loss with different thicknesses: (a)

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NiFe2O4, (b) S1, (c) S2 and (d) S3.

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NiFe2O4 S1 S2 S3

15

NiFe2O4 S1 S2 S3

8 6

ε''

12

ε'

(b)10

9

4

6 2 3 0 2

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NiFe2O4

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(e) 1.2

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NiFe2O4

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tanδm

µ'

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(d) 0.6

S1 S2 S3

1.3

12

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Frequency (GHz)

0.2 0.0

-0.2 -0.4 2

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Fig. 8. Frequency dependence of (a) ε', (b) ε'', (c) µ', (d) µ'', (e) tanδe and (f) tanδm for the samples of NiFe2O4, S1, S2 and S3.

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NiFe2O4 S1 S2 S3

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C0 (ns)

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Natural resonance

0.06 0.03 0.00

-0.03 4

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Fig. 9. Frequency dependence of the eddy current coefficient (C0) for the samples of

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Highlights 

RGO/MWCNTs/NiFe2O4 ternary nanocomposites were fabricated by a hydrothermal route. Pristine MWCNTs were directly dispersed into amphiphilic GO aqueous

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dispersions. 

Additive amount of MWCNTs had significant effect on the electromagnetic



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absorption.

Minimum reflection loss (RLmin) reached -50.2 dB with a thin thickness of 1.4

Maximum absorption bandwidth achieved 5.0 GHz with a thickness of only 1.6

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mm.

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mm.