zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band

zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band

Journal Pre-Proof Facile design of nitrogen-doped reduced graphene oxide/zinc ferrite hybrid nanocomposites with excellent microwave absorption in the...

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Journal Pre-Proof Facile design of nitrogen-doped reduced graphene oxide/zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band Ruiwen Shu, Jiabin Zhang, Yue Wu, Zongli Wan, Mingdong Zheng PII: DOI: Reference:

S0167-577X(19)31164-4 https://doi.org/10.1016/j.matlet.2019.126549 MLBLUE 126549

To appear in:

Materials Letters

Received Date: Revised Date: Accepted Date:

17 July 2019 11 August 2019 14 August 2019

Please cite this article as: R. Shu, J. Zhang, Y. Wu, Z. Wan, M. Zheng, Facile design of nitrogen-doped reduced graphene oxide/zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band, Materials Letters (2019), doi: https://doi.org/10.1016/j.matlet.2019.126549

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© 2019 Published by Elsevier B.V.

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Facile design of nitrogen-doped reduced graphene oxide/zinc ferrite hybrid nanocomposites with excellent microwave absorption in the X-band Ruiwen Shua, b,*, Jiabin Zhanga, Yue Wua, Zongli Wana, Mingdong Zhenga,* a

School of Chemical Engineering, Anhui University of Science and Technology, Huainan, 232001,

School of Earth and Environment, Anhui University of Science and Technology, Huainan, 232001,

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People’s Republic of China

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People’s Republic of China *Corresponding author:

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E-mail address: [email protected] (R. Shu), [email protected] (M. Zheng). ABSTRACT

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Herein, nitrogen-doped reduced graphene oxide/zinc ferrite (NRGO/ZnFe2O4) hybrid nanocomposites were synthesized through a facile one-pot hydrothermal strategy by using graphene oxide (GO) as a

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substrate. Results demonstrated that the additive amounts of GO had remarkable influence on the micromorphology and microwave absorption properties of NRGO/ZnFe2O4 hybrid nanocomposites. The as-prepared hybrid nanocomposites showed good dispersion of nanoparticles as the additive amounts of

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GO increasing and numerous ZnFe2O4 nanoparticles uniformly loaded on the crumpled surface of thinly flake-like NRGO were observed. It was found that the obtained hybrid nanocomposites exhibited

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obviously enhanced microwave absorption performance than that of pure ZnFe2O4. Remarkably, the minimum reflection loss reached -54.6 dB at 10.0 GHz (X-band) and effective absorption bandwidth achieved 4.2 GHz (11.8‒16.0 GHz) with a thickness of merely 2.0 mm and filler loading of 40 wt%. It

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was believed that our results could be helpful for designing and fabricating graphene-based composites as

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high-efficient microwave absorbers. Keywords: Reduced graphene oxide; Zinc ferrite; Nitrogen doping; Composite materials; Electronic materials; Microwave absorption 1. Introduction With the increasingly serious problem of electromagnetic pollution originated from the wide usage of electronic equipment, microwave absorbing materials (MAMs) have gained great attentions in the field of electromagnetic absorption [1,2]. As a kind of typical carbon nanomaterials, reduced graphene oxide (RGO) has been considered as a potential candidate for microwave absorption due to the advantages, such 1

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as uniquely laminated structure, low density, good chemical stability and strong dielectric loss [3-5]. However, single RGO used as MAMs suffers from inferior impedance matching and poor microwave absorption [3-5]. Thus, it is very urgent to enhance the microwave absorption performance of RGO for dealing with the growing problem of electromagnetic pollution.

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Recently, numerous investigations revealed that the hybridization of magnetic spinel ferrites with

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dielectric RGO or graphene was an effective strategy for obtaining good microwave absorption [7-9]. For instance, Zhao et al. prepared the flower-like [email protected] composites and observed that the

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obtained composites displayed the minimum reflection loss (RLmin) of -42.0 dB and effective absorption

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bandwidth (EAB, RL less than -10 dB) of 4.59 GHz with a filler loading of 45 wt% [7]. Yin et al. fabricated the [email protected] composites and found that the as-prepared composites showed the RLmin of -30.92 dB with a filler loading of 50 wt% [8]. In our previous studies, we fabricated

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RGO/ZnFe2O4 composites by a solvothermal route. The obtained composites exhibited the RLmin of -41.1

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dB and EAB of 3.2 GHz with a filler loading of 75 wt% [9]. However, most of the reported RGO (or graphene)-based spinel ferrites composites used as MAMs suffer from the challenges of unsatisfactory microwave absorption strength, narrow absorption bandwidth, big coating thickness and high filler

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loading, which seriously limited their practical applications in the field of electromagnetic absorption. Recently investigations revealed that nitrogen doping in the crystal lattice of RGO could not only enhance the defect or dipole polarization and dielectric loss capacity, but also optimize the impedance

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matching condition [4,5,10,11]. To the best of our knowledge, the investigations of synthesis and additive amounts of graphene oxide (GO) on the microwave absorption properties of nitrogen-doped reduced

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graphene oxide/zinc ferrite (NRGO/ZnFe2O4) hybrid nanocomposites have been rarely reported. Herein, we synthesized NRGO/ZnFe2O4 hybrid nanocomposites through a facile one-pot

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hydrothermal strategy. Moreover, the influence of additive amounts of GO on the microwave absorption of as-prepared hybrid nanocomposites was systematically investigated. Results demonstrated that the obtained hybrid nanocomposites could be used as potential microwave absorbers with strong absorption, broad bandwidth, thin thickness and low filler loading. 2. Experimental NRGO/ZnFe2O4 hybrid nanocomposites were prepared by a facile one-pot hydrothermal strategy. For simplicity, pure ZnFe2O4 nanoparticles were labeled as S1 and the as-prepared NRGO/ZnFe2O4

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hybrid nanocomposites with different additive amounts of GO were labeled as S2 (60 mg) and S3 (90 mg). The detailed preparation and characterization of NRGO/ZnFe2O4 hybrid nanocomposites and pure ZnFe2O4 nanoparticles can be found in the supplementary materials. 3. Results and discussion

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As depicted in Fig. 1(a), the diffraction peaks of the samples of S1, S2 and S3 from X-ray diffraction

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(XRD) appearing at 2 = 30.2, 35.5, 43.2, 56.8 and 62.5o are in good accordance with the (220), (311),

(400), (511) and (440) crystal planes of ZnFe2O4 (JCPDS 22-1012), respectively [6,9]. However, it is

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difficult to distinguish the diffraction peak of RGO in both S2 and S3, which could be explained by the

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relatively low degree of graphitization and diffraction strength of RGO compared with that of ZnFe2O4 in the hybrid nanocomposites [12].

The surface chemical compositions of S2 were investigated by X-ray photoelectron spectroscopy

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(XPS). Fig. 1(b) shows the typical spectrum of wide scan, which confirms that the S2 contains the

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elements of Zn, Fe, N, O and C. The atomic percentages of elements of Zn, Fe, O, N and C are 5.28%, 10.09%, 26.56%, 1.49% and 56.58%, respectively. Thus, the molar ratio of Zn: Fe: O approximates to 1:2:4, which indicates that the ZnFe2O4 has been formed in S2. Besides, the appearance of N element in

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S2, which suggests the nitrogen atoms have been successfully doped into RGO. As shown in Fig. 1(c), the peaks of C 1s at 289.2, 286.2 and 284.8 eV can be assigned to O–C=O, C–O and C–C/C=C bonds, respectively [2,6]. The N 1s spectrum (Fig. 1(d)) further indicates the nitrogen atoms have been doped

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into RGO [2]. From Fig. 1(e), the O 1 s spectra can be fitted into three peaks of Fe–O–C, O–C=O and Fe–O [6]. As depicted in Fig. 1(f), the peaks at 711.3 and 713.4 eV could be assigned to Fe 2p3/2.

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However, the peak at 725.5 eV could be ascribed to Fe 2p1/2 [2,6]. From Fig. 1(g), the peaks at 1021.9 and

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1045.0 eV could be ascribed to Zn 2p3/2 and Zn 2p1/2, respectively [2,6]. Fig. 1(h) depicts the Raman spectra of GO and S2. Two obvious peaks at around 1310 and 1595 cm-1

could be assigned to the D band (sp3 defects or disorders) and G band (sp2 hybridization) [2,9,12]. The intensity ratio of D to G band (ID/IG) of S2 shows a notable increase than that of GO, and the G band of S2 becomes weaker, suggesting a higher degree of defects originated from the reduction of GO and nitrogen doping in RGO [2,9,12]. Micromorphology and structure of S2 were characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM), respectively. As shown in Fig. S1(a)‒(c), it can be seen that

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the particles in S1 (pure ZnFe2O4) exhibit serious aggregation. With the increasing of additive amounts of GO, thinly flake-like NRGO with a rippled and crumpled morphology is clearly observed in the hybrid nanocomposites of S2 and S3 (marked by red dashed boxes in Fig. S1). Furthermore, small ZnFe2O4 nanoparticles were more uniformly distributed on the surface of RGO in S3 than that of S2. Therefore, the

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dispersion of nanoparticles in the hybrid nanocomposites is improved with the increasing of additive

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amounts of GO. From Fig. 2(a) and (b), it is clear that ZnFe2O4 nanoparticles with slight aggregation are uniformly loaded on the crumpled surface of thinly flake-like NRGO. Furthermore, it should be noted that

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almost no ZnFe2O4 nanoparticles are dropped off from the surface of NRGO under powerful ultrasound

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treatment. Therefore, it is believed that the ZnFe2O4 nanoparticles are tightly anchored on the surface of NRGO [6,9]. As shown in the high-resolution transmission electron microscopy (HRTEM) image of Fig. 2(c), the inter-plane distances of 0.246 and 0.210 nm correspond to the (311) and (400) crystal planes of

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ZnFe2O4, respectively [6,9]. Fig. 2(d) demonstrates that the nanoparticles in S2 have a small statistical

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average size of 9.40 nm.

As described in Fig. 3(a), the S1 shows the RLmin of only -2.2 dB with a thickness of 5.0 mm, which suggests very poor microwave absorption performance. From Fig. 3(b), the S2 exhibits the RLmin of -54.6

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dB at 10.0 GHz (X-band) with a thickness of 3.6 mm and EAB of 3.6 GHz (12.7‒16.3 GHz) with a thickness of 2.5 mm. As shown in Fig. 3(c), the S3 presents the RLmin of-54.5 dB at 5.0 GHz with a thickness of 5.0 mm and EAB of 4.2 GHz (11.8‒16.0 GHz) with a thickness of 2.0 mm. Thus, the hybrid

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nanocomposites exhibit obviously enhanced microwave absorption properties than pure ZnFe2O4 nanoparticles. Furthermore, the three-dimensional (3D) plot of reflection loss for S2 demonstrates that the

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RLmin corresponding to the maximum microwave absorption could locate at various frequencies by modulating the thicknesses of absorbers [2,6].

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4. Conclusions In summary, NRGO/ZnFe2O4 hybrid nanocomposites were successfully prepared by a hydrothermal

strategy. Results revealed that the additive amounts of GO had remarkable influence on the micromorphology and microwave absorption properties of as-prepared hybrid nanocomposites. With the increasing of additive amounts of GO, the hybrid nanocomposites displayed good dispersion of particles and numerous ZnFe2O4 nanoparticles were uniformly loaded on the surface of crumpled NRGO. Notably, the hybrid nanocomposites showed excellent microwave absorption properties with the RLmin of -54.6 dB

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in the X-band and EAB of 4.2 GHz for a thin thickness of merely 2.0 mm and low filler loading of 40 wt%. Therefore, the as-prepared NRGO-based hybrid nanocomposites could be used as high-efficiency microwave absorbers in the fields of military stealth and electromagnetic protection. Acknowledgments

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This work was financially supported by the National Natural Science Foundation of China (Grant No.

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51507003), China Postdoctoral Science Foundation (Grant No. 2019M652160), Foundation of Provincial

Natural Science Research Project of Anhui Colleges (Grant No. KJ2019A0119), Lift Engineering of

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Young Talents and Doctor’s Start-up Research Foundation of Anhui University of Science and

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Technology (Grant No. ZY537). References

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[2] R.W. Shu, W.J. Li, Y. Wu, J.B. Zhang, G.Y. Zhang, Chem. Eng. J. 362 (2019) 513-524.

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[3] M.S. Cao, C. Han, X.X. Wang, M. Zhang, Y.L. Zhang, J.C. Shu, H.J. Yang, X.Y. Fang, J. Yuan, J. Mater. Chem. C 6 (2018) 4586-4602.

[4] Y. Wang, X. Gao, X.M. Wu, W.Z. Zhang, C.Y. Luo, P.B. Liu, Chem. Eng. J. 375 (2019) 121942.

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[5] P.B. Liu, Y.Q. Zhang, J. Yan, Y. Huang, L. Xia, Z.X. Guang, Chem. Eng. J. 368 (2019) 285-298. [6] R.W. Shu, G.Y. Zhang, X. Wang, Xiu Gao, M. Wang, Y. Gan, J.J. Shi, J. He, Chem. Eng. J. 337 (2018) 242-255.

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[7] S.S. Wang, Y. Zhao, H.L. Xue, J.R. Xie, C.H. Feng, H.S. Li, D.X. Shi, S. Muhammad, Q.Z. Jiao, Mater. Lett. 223 (2018) 186-189.

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[8] P.F. Yin, Y. Deng, L.M. Zhang, W.J. Wu, J. Wang, X. Feng, X.Y. Sun, H.Y. Li, Y. Tao, Ceram. Int. 44 (2018) 20896-20905.

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[9] R.W. Shu, G.Y. Zhang, J.B. Zhang, X. Wang, M. Wang, Y. Gan, J.J. Shi, J. He, Mater. Lett. 215 (2018) 229-232.

[10] X. Gao, Y. Wang, Q.G. Wang, X.M. Wu, W.Z. Zhang, C.Y. Luo, J. Magn. Magn. Mater. 486 (2019) 165251. [11] J. Feng, W.M. Song, L. Sun, L.Y. Xu, RSC Adv. 6 (2016) 110337-110343. [12] C.L. Liu, S.H. Luo, H.B. Huang, Y.C. Zhai, Z.W. Wang, ChemSusChem 12 (2019) 873-880. Figure captions

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Fig. 1. XRD patterns of S1, S2 and S3 (a), XPS spectra of wide scan (b), C 1s (c), N 1s (d), O 1s (e), Fe 2p (f) and Zn 2p (g) for S2, Raman spectra of GO and S2 (h). Fig. 2. TEM images with different magnifications: (a) and (b), HRTEM image (c), particle size distribution histogram of ZnFe2O4 nanoparticles (d) of S2.

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Fig. 3. Frequency dependence of reflection loss with different thicknesses: (a) S1, (b) S2 and (c) S3; (d)

(c)

S2

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Binding Energy (eV)

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280 282 284 286 288 290 292 294 296 298

Binding Energy (eV)

(f)

Fe 2p

Raw Fitted curve Fe 2p3/2 Fe 2p3/2 Fe 2p1/2

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545

700

705

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(h) Intensity (a.u.)

Zn 2p1/2

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Intensity (a.u.)

Zn 2p3/2

1015 1020 1025 1030 1035 1040 1045 1050

Fig. 1

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715

D G

ID/IG = 1.26

S2

ID/IG = 0.89

GO

1000 1200 1400 1600 1800 2000 2200 2400

Binding Energy (eV)

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Binding Energy (eV)

Binding Energy (eV)

(g) Zn 2p

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Raw Fitted curve Fe-O O-C=O Fe-O-C

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Intensity (a.u.)

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Binding Energy (eV)

(e) O 1s

N 1s

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0

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Intensity (a.u.)

(d)

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Raw Fitted curve C-C/C=C C-O O=C-O

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O 1s Fe 2p C 1s N 1s

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Intensity (a.u.)

Intensity (a.u.)

S3

S2

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C 1s

Zn 2p

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(b)

(440)

(511)

(400)

Intensity (a.u.)

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(311)

3D plot of reflection loss for S2.

Raman shift (cm-1)

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Fig. 2

-1.5 -2.0 -2.5

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EAB = 4.2 GHz

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RLmin = -54.5 dB 4

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10 12 14 16 18 20 22

Frequency (GHz) S3

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d / mm 1.0 1.5 2.0 EAB = 3.6 GHz 2.5 3.0 3.5 3.6 4.0 4.5 RLmin = -54.6 dB 5.0

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Frequency (GHz)

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S2

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Reflection Loss (dB)

Reflection Loss (dB)

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

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-0.5

-60

(b)

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Reflection Loss (dB)

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

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Frequency (GHz) Fig. 3 7

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Conflict of interest Dear Editor, We declare that we have no conflict of interest. Signed by all authors as follows: Ruiwen Shu*, Jiabin Zhang, Yue Wu, Zongli Wan,

(c)

S2

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Binding Energy (eV)

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280 282 284 286 288 290 292 294 296 298

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Binding Energy (eV)

Raw Fitted curve Fe-O O-C=O Fe-O-C

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Intensity (a.u.)

396

400

Binding Energy (eV)

(e) O 1s

N 1s

392

0

80

(f)

530

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Fe 2p

Intensity (a.u.)

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2 (o)

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(h) Intensity (a.u.)

Zn 2p1/2

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Zn 2p3/2

1015 1020 1025 1030 1035 1040 1045 1050

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Binding Energy (eV)

Binding Energy (eV)

(g) Zn 2p

Raw Fitted curve C-C/C=C C-O O=C-O

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O 1s Fe 2p C 1s N 1s

S1 20

Intensity (a.u.)

Intensity (a.u.)

S3

S2

10

C 1s

Zn 2p

O

(b)

(440)

(511)

(400)

Intensity (a.u.)

(220)

(a)

(311)

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Mingdong Zheng.

D G

ID/IG = 1.26

S2

ID/IG = 0.89

GO

1000 1200 1400 1600 1800 2000 2200 2400

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Binding Energy (eV)

Raman shift (cm-1)

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Fig. 1. XRD patterns of S1, S2 and S3 (a), XPS spectra of wide scan (b), C 1s (c), N 1s (d), O 1s (e), Fe 2p (f) and Zn 2p (g) for S2, Raman spectra of GO and S2 (h).

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Fig. 2. TEM images with different magnifications: (a) and (b), HRTEM image (c), particle size distribution histogram of ZnFe2O4 nanoparticles (d) of S2.

-1.0 -1.5

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-2.0

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-2.5

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4

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(b)

S1

Reflection Loss (dB)

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-0.5

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Reflection Loss (dB)

(a) 0.0

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

S2

0

d / mm 1.0 1.5 2.0 EAB = 3.6 GHz 2.5 3.0 3.5 3.6 4.0 4.5 RLmin = -54.6 dB 5.0

-10 -20 -30 -40 -50 -60

10 12 14 16 18 20 22

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Frequency (GHz)

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10 12 14 16 18 20 22

Frequency (GHz)

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S3

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-20 -30

EAB = 4.2 GHz

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RLmin = -54.5 dB

-60 2

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

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-10

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Reflection Loss (dB)

(c)

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Frequency (GHz)

Fig. 3. Frequency dependence of reflection loss with different thicknesses: (a) S1, (b) S2 and (c) S3;

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Graphical Abstract

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(d) 3D plot of reflection loss for S2.

Highlights 

NRGO/ZnFe2O4 hybrid nanocomposites were fabricated by a facile hydrothermal route.



ZnFe2O4 nanoparticles were uniformly loaded on the crumpled surface of NRGO.



Additive amounts of GO had notable influence on microwave absorption properties. 10

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Optimal reflection loss was -54.6 dB in the X-band with a filler loading of 40 wt%.



Maximum absorption bandwidth reached 4.2 GHz with a thickness of merely 2.0 mm.

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