Coupling Hollow Fe 3 O 4 -Fe Nanoparticles with Graphene Sheets for High-performance Electromagnetic Wave Absorbing Material

Transcription

1 Supporting Information Coupling Hollow Fe 3 O 4 -Fe Nanoparticles with Graphene Sheets for High-performance Electromagnetic Wave Absorbing Material Bin Qu,,#,, Chunling Zhu, *, Chunyan Li, Xitian Zhang, # Yujin Chen *, Key Laboratory of In-Fiber Integrated Optics, Ministry of Education, and College of Science, Harbin Engineering University, Harbin , China College of Material Science and Chemical Engineering, Harbin Engineering University, Harbin , China # Key Laboratory for Photonic and Electronic Bandgap Materials, Ministry of Education, and School of Physics and Electronic Engineering, Harbin Normal University, Harbin , China. Department of Applied Chemistry, College of Science, Northeast Agricultural University, Harbin , China *Corresponding authors. addresses: chenyujin@hrbeu.edu.cn and zhuchunling@hrbeu.edu.cn S-1

2 Experimental Details: Pg S-3 Figure S1: M-H loop of the hollow Fe 3 O 4 -Fe /G composite. Pg S-5 Figure S2: (a) The complex permittivity, (b) the complex permeability of the hollow Fe 3 O 4 -Fe/G composite,(c) the dielectric loss tangent, (d) the magnetic loss tangent. Pg S-5 Figure S3:Reflection losses map of the hollow Fe 3 O 4 -Fe /G composite. Pg S-6 Figure S4: (a) The minimal reflection loss (R L ) value of the solid Fe 3 O 4 -Fe/G nanocomposites at d = mm, (b) comparison of the calculated matching thickness (t fi ) under n = 1 to the values (t exp m ) obtained from R L values shown in a), and (c) the normalized input impendence ( Z in /Z 0 ) for the solid Fe 3 O 4 -Fe/G nanocomposites. Pg S-6 fit Table S1: Comparison of values between hollow Fe 3 O 4 -Fe/G and solid Fe 3 O 4 -Fe/G Pg S-7 Table S2: Comparison of Z values between hollow Fe 3 O 4 -Fe/G and solid Fe 3 O 4 -Fe/G Pg S-7 S-2

3 Experimental details Materials. Graphene sheets with a thickness of about 0.8 nm were purchased from Nanjing XFNANO Material Tech Co., Ltd. (Nanjing City, China). Ferric nitrate were purchased from Tianjin Kermel Chemical Reagent Co., Ltd. (China). Synthesis of hollow Fe 3 O 4 -Fe/G composite. We first synthesized FeOOH nanoparticle/g composite according to our previously reported method. Typically, 20 mg of the graphene was dispersed into 600 ml water, and 8.0 g of ferric nitrate was added. The mixture above was kept at 55 o C for 2.5 h under stirring. The precipitates were washed with distilled water and dried under vacuum by 40 o C for 12 h. The FeOOH nanoparticle/g composite was first treated in a furnace at 420 o C for 3 h under an Ar/H 2 flow. The obtained powder was treated in a furnace at 200 o C for 3 h and then at 250 o C for 2 h under air. After the furnace being cooled to room temperature, the hollow Fe 2 O 3 nanoparticle/g composite was obtained. Finally the hollow Fe 3 O 4 -Fe/G composite was fabricated after heating the hollow Fe 2 O 3 nanoparticle/g composite in a furnace at 360 o C for 2 h under an Ar/H 2 flow. Structure Characterization. The morphology and size of the samples were characterized by scanning electron microscope (Hitachi SU 70) and a FEI Tecnai-F20 transmission electron microscope equipped with a Gatan imaging filter (GIF). The crystal structure of the sample was determined by X-ray diffraction (XRD; D/max-2600/PC, Rigaku, Japan) with Cu Kα radiation (λ = Å) in the 2θ of XPS measurements were carried out by using a spectrometer with Mg Kα radiation (PHI 5700 ESCA System).The binding energy was calibrated with the C 1s position of contaminant carbon in the vacuum chamber of the XPS S-3

4 instrument (284.6 ev). The magnetic properties were measured by a vibrating sample magnetometer (VSM; Lakeshore 7410) at room temperature. Electromagnetic parameter measurements. The EM parameters of samples were measured by using the transmission/refection coaxial line method. The measurement setup consisted of in a vector network analyzer (Anritsu MS4644A Vectorstar) with a synthesized sweep oscillator source and an S parameter test set in the frequency of 2 18 GHz. The cylindrical sample (with 3.00 mm inner diameter, 7.00 mm outer diameter and 3.00 mm thickness) was fabricated by uniformly mixing 18 wt% of the sample with a paraffin matrix. Before measurement, the electromagnetic parameter was verified by standard Teflon sample with the same shape and size as the tested sample. The transmission line theory was introduced to characterize the wave-absorbing properties. S-4

5 Figure S1 M-H loop of the hollow Fe 3 O 4 -Fe /G composite. Figure S2 (a) The complex permittivity, (b) the complex permeability of the hollow Fe 3 O 4 -Fe/G composite, (c) the dielectric loss tangent, (d) the magnetic loss tangent. S-5

6 Figure S3 Reflection loss map for the hollow Fe 3 O 4 -Fe/G composite. Figure S4 (a) The minimal reflection loss (R L ) value of the solid Fe 3 O 4 -Fe/G nanocomposites at d = mm, (b) comparison of the calculated matching thickness ( fit ) under n = 1 to the values ( exp ) obtained from R L values shown in a), and (c) the normalized input impendence ( Z in /Z 0 ) for the solid Fe 3 O 4 -Fe/G nanocomposites. S-6

7 Table S1 Comparison of the difference between fit and exp values for hollow Fe 3 O 4 -Fe/G and solid Fe 3 O 4 -Fe/G exp (mm) fit (mm) for hollow Fe 3 O 4 -Fe/G fit (mm) for solid Fe 3 O 4 -Fe/G Table S2 Comparison of Z values between hollow Fe 3 O 4 -Fe/G and solid Fe 3 O 4 -Fe/G exp (mm) Z for hollow Fe 3 O 4 -Fe/G Z for solid Fe 3 O 4 -Fe/G S-7