www.sciencemag.org/content/353/6304/1137/suppl/DC1

Supplementary Materials for

Electromagnetic interference shielding with 2D transition metal carbides (MXenes)

Faisal Shahzad, Mohamed Alhabeb, Christine B. Hatter, Babak Anasori, Soon Man Hong,

Chong Min Koo,* Yury Gogotsi*

*Corresponding author. Email: gogotsi@drexel.edu (Y.G.); koo@kist.re.kr (C.M.K.)

Published 9 September 2016, Science 353, 1137 (2016) DOI: 10.1126/science.aag2421

This PDF file includes:

Materials and Methods Supplementary Text Figs. S1 to S6 Tables S1 to S3 Full reference list

2

Materials and Methods

Materials Lithium fluoride (LiF, Alfa Aesar, 98.5%), hydrochloric acid (HCl, Fisher Scientific, 37.2%), hydrofluoric acid (HF, Acros Organics, 49.5 wt.%,), tetrabutylammonium hydroxide (TBAOH, Acros Organics, 40 wt.% solution in water), and alginic acid sodium salt (sodium alginate, Sigma Aldrich) were used as received. Aluminum (8 µm) and copper foils (10 µm) were purchased from Alfa Aesar.

Synthesis of Ti3AlC2 (MAX phase) Ti3AlC2 was synthesized as described elsewhere (33), and the powders were crashed and sieved through a 400 mesh size sieve (≤38 µm particle size) and collected for etching.

Minimally Intensive Layer Delamination (MILD) Synthesis of Ti3C2Tx Ti3C2Tx was synthesized using a modified etching route to clay method (34), by using a higher LiF:Ti3AlC2 molar ratio than the clay method (7.5:1 instead of 5:1) and no sonication was used for the delamination step. We designated this modified route as minimally intensive layer delamination (MILD) method because it promotes delamination of Ti3C2Tx, without the sonication step previously needed to delaminate Ti3C2Tx. In this process, the etchant solution was prepared by completely dissolving 1 g LiF in 20 ml of 6 M HCl in 100 ml-polypropylene plastic vial, after which 1 g of Ti3AlC2 was gradually added to the etchant solution and the reaction allowed to proceed at 35 °C for 24 h. The acidic product was washed copiously with deionized water (DI H2O) via centrifugation at 3500 rpm several times for 5 min per cycle until a stable dark-green supernatant solution of Ti3C2Tx flakes, with a pH of ≥ 6, was obtained. At this stage, if the dark supernatant is decanted, swelled clay-like sediment is observed. Adding DI water to the sediment and manually shaking it for < 5 min results in delamination of the flakes. After 1 h centrifugation at 3500 rpm, the resulting supernatant has MXene concentration of ~ 1.5 mg ml–1. It’s worth mentioning that using HCl concentration larger than 6M (e.g., 9M) leads to delamination of Ti3C2Tx and an even higher concentration of MXene in colloidal solution, because the higher concentration of protons (H+) that acid provides and their exchange with Li+ promote the delamination of Ti3C2Tx.

Synthesis of Mo2TiC2Tx and Mo2Ti2C3Tx 1 g of Mo2TiAlC2 was etched in 10 ml solution of 10 wt.% HF and 10 wt.% HCl at 40 °C for 40 h. The product was washed with DI H2O until neutralized before being collected and dried in vacuum overnight. Mo2Ti2C3Tx was synthesized by etching Mo2Ti2AlC3 using the same conditions as in synthesis of Mo2TiAlC2.

Delamination of Mo2TiC2Tx and Mo2Ti2C3Tx 1 g of Mo2TiC2Tx and 1 g Mo2Ti2C3Tx were separately stirred in 50 ml of H2O containing 0.8 wt.% TBAOH for 2 h before collecting the colloidal solution via centrifugation after 1 h at 3500 rpm.

3

Preparing Ti3C2Tx-Sodium Alginate (SA) Composite Ti3C2Tx was synthesized following the MILD method explained earlier and washed for six to seven times until the pH of ~ 5-6 via centrifugation. After decanting the supernatant, the swelled clay-like sediment was redispersed in DI H2O in a wide-mouth jar and ultrasonicated in an ice bath using Bransonic Ultrasonic Cleaner (Branson 2510) for 1 h under Argon (Ar) gas purging. The mixture was then centrifuged at 3500 rpm for 1 h and the delaminated Ti3C2Tx supernatant was collected and stored for future experiments. An aqueous SA solution with concentration of 0.5 mg ml–1 was prepared by completely dissolving desired SA content into deionized water. Subsequently, aqueous Ti3C2Tx colloidal solution, based on the desired final Ti3C2Tx content, was added to SA solution and resultant mixture was then stirred for 24 h at RT yielding a series of aqueous Ti3C2Tx-SA solutions with different initial Ti3C2Tx contents (90, 80, 60, 50, 30, 10 wt.%). This corresponds to approximately 74, 55, 32, 24, 12, and 3 vol.% of Ti3C2Tx. Each aqueous Ti3C2Tx-SA solution was filtered using a polypropylene membrane (Celgard, pore size 0.064 µm). It is important to mention that the polymer content in the membranes may be lower than in the solution due to possibility of some of the polymer going through the filter, especially at lower MXene contents. However, this should not affect the observed trends. Each VAF sample was allowed to filter until dry for 24-72 h at RT. Samples were designated as follows: for example, a 90 wt.% Ti3C2Tx with 10 wt.% SA will be referred to as 90 wt.% Ti3C2Tx-SA. Pure Ti3C2Tx film was filtered using the same method for comparison.

Preparation of Freestanding Films of Ti3C2Tx, Mo2TiC2Tx, Mo2Ti2C3Tx, and Ti3C2Tx-SA Composites All freestanding films were prepared via vacuum-assisted filtration (VAF) using Durapore filter membrane (polyvinyldifluoride PVDF, Hydrophilic, with 0.1 µm pore size) to make Ti3C2Tx, Mo2TiC2Tx, and Mo2Ti2C3Tx films and using Celgard filter membrane (polypropylene, pore size 0.064 µm) to make Ti3C2Tx-SA composite films. All films were allowed to dry at room temperature (RT) before being easily peeled off as freestanding films (see Fig S1) and stored under vacuum for future use.

Spray-Coated Ti3C2Tx Film on Polyethylene Terephthalate A strong and large film is required to handle the heavy weight (~ 13 kg) of ASTM coaxial sample holder used for EMI SE measurement at low frequencies. Accordingly, thin and large area Ti3C2Tx film (20 × 27 cm2) with thickness of ~ 4 µm (see Fig. S1) was prepared by spray coating an aqueous solution of Ti3C2Tx (10 mg/ml) on a 29 × 23 cm2 PET flexible substrate, which was subjected to continuous drying using an air gun. The dried Ti3C2Tx film was subsequently laminated between PET sheets using a commercial laminator (Staples, multiuse laminator) resulting in a PET-Ti3C2Tx-PET sandwich-like structure. For control measurement, a plain PET sheet was laminated in a similar manner.

Materials Characterization Morphology of the composite films was investigated by scanning electron microscopy (SEM) (Zeiss Supra 50VP, Germany). X-ray diffraction (XRD) analysis was carried out using a Rigaku Smartlab (Tokyo, Japan) diffractometer with Cu-Kα radiation (40 kV and 44 mA); step scan 0.02°, 3°-70° 2 theta range, step time of 0.5 s, 10 × 10 mm2 window slit. Sample structure was

4

characterized using Transmission Electron Microscopy (TEM) (JEOL-2100, Japan) at an acceleration voltage of 200.0 kV.

Electromagnetic Interference Shielding Characterization Electromagnetic interference shielding measurements of pristine as well as composite films were carried out in a WR-90 rectangular waveguide using a 2-port network analyzer (ENA5071C, Agilent Technologies, USA) in X-band frequency range (8.2-12.4 GHz). The dynamic range of network analyzer was 80 dB. A standard procedure for calibrating the equipment was performed using short offset, short and load on both ports, 1 and 2. The samples were cut into a rectangular shape, slightly larger in dimension (25 × 12 mm2) as compared to the opening of the sample holder (22.84 × 10.14 mm2). Scotch tape was attached to one end of the film to mount it onto the sample holder. While mounting the film onto the sample holder, extra care was taken to avoid any leakage paths from the edges. The sample holder was tightly fixed with screws and spring-loaded clamps. The distance from sample to port 1 was set as 0, and the length of the sample holder was fixed as 140 mm. Electromagnetic wave has an incident power of 0 dBm, which corresponds to 1 mW. Thickness of samples ranged from 1 µm to about 45 µm for different MXenes and composite films.

The low frequency EMI SE measurement (30 MHz-1.5 GHz) was performed in accordance with ASTM D4935-99 by using a standard enlarged coaxial transmission line sample holder. The reference and load samples for EMI testing were cut into the required shape from the laminated PET-Ti3C2Tx-PET sheet in accordance with ASTM specifications. The reference samples consist of two pieces, a ring-shaped piece with outer and inner diameters of 133.1 mm and of 76.2 mm, respectively, and a circular piece having a diameter of 33.0 mm. The load sample was made by cutting the PET-Ti3C2Tx-PET sheet into a circular shape with an outer diameter of 133.1 mm. Double-sided tape was used to mount the reference and load samples in between the two halves of the sample holder. PET films, that are perfect insulators and transparent to EM radiation, showed ~ 0 dB and did not affect the EMI SE of the laminated Ti3C2Tx film.

Electrical conductivity of all samples was measured using a linear four-pin probe (MCP-TP06P PSP) with a Loresta-GP meter (MCP-T610 model, Mitsubishi Chemical, Japan). Inter-pin distance of the probe was 1.5 mm and voltage at the open terminal was set as 10 V. Samples for electrical conductivity measurements were made by punching the MXene films with a 10 mm custom designed stainless steel cutter. Four-pin probe was placed at the center of the thin films and sheet resistance was recorded. Electrical conductivity of all the samples was calculated by the equation:

σ = (Rst)–1, (1)

where σ is the electrical conductivity [S cm–1], Rs is the sheet resistance [Ω sq–1] and t is the thickness of samples [cm–1]. Thickness measurements were performed by using a highly accurate length gauge (±0.1 µm) of Heidenhain Instruments (Germany) and counter checked by the SEM technique. The density of pure MXene and composite samples was calculated from experimental measurements of the volume and mass of the samples.

5

Supplementary Text

Electromagnetic Interference (EMI) Shielding Measurements The electromagnetic interference shielding effectiveness (EMI SE), is a measure of material’s ability to block electromagnetic waves. For electrically conductive materials, theoretically, EMI SE can be represented by Simon formalism (7, 36);

𝑆𝐸   = 50+ 10 log   !!+ 1.7𝑡 𝜎𝑓   (2)

Where, σ [S cm–1] is the electrical conductivity, f [MHz] is the frequency and t [cm] is the thickness of shield. Thus EMI SE shows strong dependence on electrical conductivity and thickness of the shielding material.

Experimentally, EMI SE is measured in decibels [dB] and defined as the logarithmic ratio of incoming power (PI) to transmitted power (PI) as (2, 37);

Shielding effectiveness 𝑆𝐸   𝑑𝐵 = 10 log !!!!

(3)

When an electromagnetic radiation is incident on shielding device, the reflection (R), absorption (A), and transmission (T) must add up to 1, that is,

R+ A+ T = 1 (4)

The reflection (R) and transmission (T) coefficients were obtained from the network analyzer in form of scattering parameters, “Smn”, which measure how energy is scattered from a material or device. The first letter “m” designate the network analyzer port receiving the EMI radiation and the second letter “n”, represents the port that is transmitting the incident energy. Vector network analyzer directly gives the output in form of four scattering parameters (S11, S12, S21, S22), which can be used to find the R and T coefficients as:

R=|𝑆!!|! =   |𝑆!!|! (5)

T= |𝑆!"|! =   |𝑆!"|! (6)

The total EMI SE (EMI SET) is the sum of the contributions from reflection (33), absorption (SEA) and multiple internal reflections (SEMR). At higher EMI SE values, and with a multilayer EMI shield (as in the case of MXenes), contribution from multiple internal reflection is merged in the absorption, because the re-reflected waves get absorbed or dissipated in form of heat in the shielding material. The total SET can be written as (8);

𝑆𝐸!   =  𝑆𝐸!   +  𝑆𝐸! (7)

6

The effective absorbance (Aeff), a measure of the absorbed electromagnetic waves in a material can be described as:

𝐴!""   =  !!!!!!!!

(8)

SER and SEA can be expressed in terms of reflection and effective absorption considering the power of the incident electromagnetic waves inside the shielding material as (8, 37):

𝑆𝐸!   = 10 log   !!!!

= 10 log   !!!|!!!|!

(9)

𝑆𝐸!   = 10 log   !!!!!""  

= 10 log   !!!!

= 10 log   !!|!!!|!

|!!"|! (10)

Calculation of Specific Shielding Effectiveness (SSE) Specific shielding effectiveness (SSE) is derived to compare the effectiveness of shielding materials taking into account the density. Lightweight materials (with low density), deliver high SSE. The SSE parameter is relative, and high values show more suitability of a particular material.

Mathematically, SSE can be obtained by dividing the EMI SE with density of material as follow (27, 31);

SSE = EMI SE/density = dB cm3 g–1 (11)

SSE has a basic limitation, that is, it does not account for the thickness information. Higher values of SSE can simply be obtained at large thickness while maintaining the low density. However, large thickness increases the net weight and is disadvantageous. To account for the thickness contribution, following equation is used to evaluate the absolute effectiveness (SSEt) of a material in relative terms (27, 31):

SSEt= SSE/t = dB cm3 g–1 cm-1 = dB cm2 g–1 (12)

Calculation of EMI Shielding Efficiency (%) EMI shielding efficiency presents the material ability to block waves in terms of percentage. For example, EMI SE of 10 dB corresponds to 90% blockage of incident radiation, 30 dB corresponds to 99.9% blockage of incident radiation, respectively (Table S1) (27). EMI shielding effectiveness [dB] is converted into EMI shielding efficiency [%] using the equation (2) as:

Shielding efficiency (%) = 100 - !

!"!"!"

 ×  100 (13)

7

Fig. S1. Optical images of free-standing films. Digital photographs of (A) Ti3C2Tx, (B) Mo2TiC2Tx, and (C) Mo2Ti2C3Tx films, which were made using VAF, (D) laminated Ti3C2Tx film was spray-coated on PET.

Fig. S2. TEM image 30 wt.% Ti3C2Tx-SA composite. Restacking of Ti3C2Tx MXene in sodium alginate binder leads to regions of multilayer MXene within the polymer matrix.

8

Fig. S3. Experimental and theoretical EMI SE of a Ti3C2Tx film. (A) EMI SE of a 6-µm Ti3C2Tx film. Theoretical EMI SE values, derived by using equation 2 in a broad frequency range, are compared with experimentally calculated values in X-band. Calculated results predict high EMI SE values at low frequencies as well. (B) Experimental EMI SE measurements on a 4-µm spray-coated and laminated MXene film (PET-Ti3C2Tx-PET) show similar EMI SE values at lower and higher frequencies.

Fig. S4. EMI SE of Ti3C2Tx-SA composites. Variation of EMI SE upon increasing the Ti3C2Tx content in the sodium alginate polymer matrix at 8.2 GHz.

9

Fig. S5. Specific EMI shielding of MXene and other materials. SSE/t vs. thickness comparison of MXenes and their composites with previously reported EMI shielding materials. Data taken from Table S3.

10

Fig. S6. EMI SE comparison of MXene and its composite with known materials of comparable thickness. Measured EMI SE (maximum) values of thin films of sodium alginate (thickness: 9 µm), 90 wt.% Ti3C2Tx-SA (8 µm), Ti3C2Tx (11.2 µm), aluminum (8 µm) and copper (10 µm) in X-band range. Sodium alginate being electrical insulator is transparent to electromagnetic waves (close to 0 dB). For comparison, a previously reported value for rGO film (8.4 µm thick) is shown (32). The numbers are presented in Table S3.

Table S1. Relationship between shielding effectiveness (dB) and shielding efficiency (%)

Shielding Effectiveness (dB)

Shielding Efficiency (%)

0 0 10 90 20 99 30 99.9 40 99.99 50 99.999 60 99.9999 70 99.99999 80 99.999999 90 99.9999999 92 99.99999994

11

Table S2. EMI shielding performance of various shielding materials Type Filler Filler

[wt.%] Matrix Thickness

[mm] Conductivity

[S m–1] EMI SE

[dB]* Ref

Red

uced

gra

phen

e ox

ide

(rG

O)

rGO 7 PS 2.5 43.5 45.1 (2) rGO 10 PEI 2.3 0.001 22 (37) rGO 0.7 PDMS 1 180 30◊ (1) rGO 20 Wax 2.0 < 0.1 29Δ (38) rGO 60# Wax 0.35 2500 27 (39) rGO 7.5 WPU 1 16.8 34 (40) rGO 15 Epoxy / 10 21 (21) rGO 30 PS 2.5 1.25 29 (41) rGO 10 PU 60 0.06 39.4 (28) rGO 4 PI 0.073 2x 105 51 (31) rGO 33 PANI 2.8 1800 34.2Δ (42) S-doped rGO 15 PS 2 33 24.5§ (43) B,N-doped rGO Bulk / 1.2 124 42Δ (44) S-doped rGO Bulk / 0.15 3.1 x 104 38.5§ (22) Graphene film Bulk / 0.25 / 17Δ (45) Graphene film Bulk / 0.050 1.13 x 104 60 (46) Graphene film Bulk / 0.008 105 20 (32) Graphene film Bulk / 0.015 2.4 x 104 20.2§ (47) Graphene foam Bulk / 0.3 310 25 (48)

rGO

with

mag

netic

fille

rs

rGO/δ-Fe2O3 40 PVA 0.36 3 20.3 (39) rGO/γ-Fe2O3 75 PANI 2.5 80 51 (49) rGO/Fe3O4 35 PVA 0.3 < 0.1 15 (50) rGO/Fe3O4 66 PANI 2.5 260 30Δ (51) rGO/CF/γ-Fe2O3 50 Resin 0.4 1.7 x 104 41.8 (52) rGO/Fe3O4 10 PVC 1.8 7.7 × 10–4 13 (53) rGO/Fe3O4 10 PEI 2.5 10–4 18 (54) rGO/MnO2 Bulk / 3 / 57Δ (55) rGO/Fe3O4 Bulk / 0.25 5000 24 (56) rGO/Fe3O4 Bulk / 3 700 41 (57) rGO-BaTiO3 Bulk / 1.5 / 41.7 (58) rGO-Ba Ferrite Bulk / 1 98 18 (59) rGO/CNT/Fe3O4 Bulk / 2 / 37.5Δ (60)

Gra

phite

/ CB

CB 15 SEBS 5 22 20 (61) Graphite 25# PA 6,6 3.2 / 12§ (62) Graphite 7.05# PE 2.5 10 51.6 (63) Graphite 18.7# PE 3 / 33 (64) Graphite 2 Epoxy 5 2.6 11 (65) Graphite 15 ABS 3 16 60 (66)

Car

bon

nano

tube

s MWCNT 76 WPU 0.8 2.1x 103 80 (23) CNT 0.66 Epoxy 2 516 33 (30) MWCNT 76.2 WPU 4.5 44.6 50 (31) MWCNT 15 Cellulose 0.15 / 35◊ (67) MWCNT 40 PMMA 0.165 1000 27§+ (68)

12

MWCNT 15 PEDOT 2.8 1935 58Δ (69) MWCNT 10 PTT 2 30 42Δ (70) SWCNT 15 Epoxy 2 20 25 (71) SWCNT 20 PU 2 2.2 x 10-4 17 (72) CNT 7 PS / / 18.5 (29) CNT 25 Coal tar 0.6 1.1 x 103 -56 (73)

Car

bon

fiber

CF/Fe3O4 10 Epoxy 13 0.2 20 (74) CF/Fe3O4 5 PDMS 0.7 710 67.9 (75) CF 40# PES 2.87 / 38§ (76) CF 10 PVDF 0.05 180 14◊ (77) CF 10# PP 3.2 10 25 (78) CF 15 PS / 0.1 19 (79) CF/CNT 13 PS 1 0.215 21.9Δ (80) CF-GN 17.2 Wax 0.27 800 28 (81)

Ni 10# PP 3 100 20 (35) Ni/CB 50 Resin 1 31.6 85 (82) Ni 40# PVDF 1.95 <0.1 23 (83) Ni Fiber 7# PES 2.85 / 58§ (84)

M

etal

s

Ni-Co Fiber 30 Wax 2.5 1.3 x 103 41.2 (85) Ag/CF 4.5 Epoxy 2.5 / 38 (86) Ag Nanowires 75 phr Epoxy 0.040 4.7 x 103 35 (87) Ag Nanowires 14# PANI 0.013 5.3 x 105 50 (88) Ag Nanowires 2.5# PS 0.8 1.9 x 103 33 (89) Cu/Graphite 20 PVC 2 80 70 (90) Cu Nanowires 2.1# PS 0.2 / 35 (91) Al Flakes 20# PES 2.9 / 39§ (76) SS 1.1# PP 3.1 0.1 48 (27) SS 10# PES 3.08 / 35 (76) SS Bulk / 4 / 89§ (84) Copper Bulk / 3.1 / 90§ (84) Cu Foil Bulk / 0.010 8.0 x 107 70 This work Al Foil Bulk / 0.008 2.8 x 107 66 This work

Oth

ers

Flexible graphite Bulk / 3.1 1.351 x 105 130 (92) Flexible graphite Bulk / 0.79 1.351 x 105 102 (92) Carbon Foam Bulk / 2 2.4 x 102 51.2 (93) Carbon Foam Bulk / 2 126.5 40§ (94) MoS2 30 Glass 1.5 100 24.2 (95) MoS2 60 Wax 2.4 2.2 x 10–5 -38 (RL) (96) rGO-SiO2 Bulk / 1.5 33 38 (97) Ni Ferrite / PVDF 2 / 67 (98) Fe2O3/ash 60 PP 2 1 25.5Δ (24) Ba Ferrite 38.2 PPY 2 >1 12 (25) Fe2O3 / PEDOT 6 40 22.8 (99) Ba Ferrite* / PEDOT / / 22.5Δ (100) Carbon Aerogel Bulk / 10 133.3 51 (101) Zn Ferrite 50 PPY 2.7 / -29 (RL) (102) Mn Ferrite 15 PPY 1.5 / -12 (RL) (103)

13

* Values in bracket indicate maximum EMI SE value in measured range. EMI SE is obtained mainly in X-band (8.2-12.4 GHz), except otherwise specified; / - values not provided; # - Vol. %; RL - Reflection loss; SS - Stainless steel; Bulk - 100% pure material with no polymeric binder; Δ - Ku-band (12.4-18 GHz); § - L and S-band; 1-4 GHz; ◊ - Ultra high frequency (UHF); + -C band.

Table S3. Specific EMI shielding performance optimized with thickness of various shielding materials

Type Filler Filler [wt.%]

Matrix t [cm]

SE [dB]

SSE [dB cm3g-1]

SSE/t [dB cm2g-1]

Ref

Foam

Stru

ctur

es

C

arbo

n B

ased

rGO 10 PEI 0.23 12.8 44 191.3 (37) rGO 30 PS 0.20 29 64.4 257.6 (41) rGO 16 PI 0.08 21 937 11712 (106) rGO/ Fe3O4 10 PEI 0.25 18 44 176 (54) SWCNT 7 PS 0.12 18.5 33 275 (29) MWCNT 76.2 WPU 0.1 21.1 541 5410 (31) Carbon / PN resin 0.2 51.2 341 1705 (93) Carbon foam Bulk / 0.2 40 241 1250 (94)

Met

al

Bas

ed CuNi Bulk /   0.15 25 104 690 (107)

CuNi-CNT Bulk /   0.15 54.6 237 1580 (107) Ag nanowires 4.5 PI 0.5 35 1208 2416 (108) SS 1.1# PP 0.31 48 75 241.9 (27)

Solid

Stru

ctur

es Car

bon

Bas

ed

rGO 7 PS   0.25 45.1 173 692 (2) rGO/ Fe3O4 Bulk / 0.03 24 31 1033 (56) rGO 25 PEDOT   0.08 70 67.3 841 (109) MWCNT 20 PC   0.21 39 34.5 164 (110) MWCNT 15 ABS 0.11 50 47.6 432.7 (8) MWCNT 20 PS 0.2 30 57 285 (111) CB 15 ABS 0.11 20 20.9 190 (8) CB 37.5 EPDM 0.2 18 30.3 15.1 (112)

Met

al B

ased

Copper Bulk /   0.31 90 10 32.3 (84) SS Bulk /   0.4 89 11 27.5 (84) Ni fiber 7# PES 0.285 58 31 108.7 (84) Ni filaments 7# PES 0.285 87 47 164.9 (84) Al Foil Bulk / 0.0008 66 24.4 30555 This

work Cu Foil Bulk /   0.0010 70 7.8 7812

MX

ene

s

*Ti3C2Tx Bulk / 0.0011 68 28.4 25863 This work

*Ti3C2Tx 90 SA 0.0008 57 24.6 30830 *Densities of pure Ti3C2Tx and 90 wt.% Ti3C2Tx-SA were ca. 2.39 and 2.31 g cm–3, respectively; / indicates that the values were either not available or impossible to calculate. Thin MXene films show a better specific EMI shielding.

Fe3O4 40 PANI 2 / -33 (RL) (104) Carbonyl Iron 50 PPY 2.2 / -39 (RL) (105)

MX

enes

Mo2TiC2Tx Bulk / 0.004 1.0 x 104 23 This work

Mo2Ti2C3Tx Bulk / 0.0035 2.5 x 104 26 Ti3C2Tx Bulk / 0.045 4.8 x 105 92 Ti3C2Tx 90 SA 0.008 2.9 x 105 57

References and Notes 1. Z. Chen, C. Xu, C. Ma, W. Ren, H. M. Cheng, Lightweight and flexible graphene foam

composites for high-performance electromagnetic interference shielding. Adv. Mater. 25, 1296–1300 (2013). Medline doi:10.1002/adma.201204196

2. D. X. Yan, H. Pang, B. Li, R. Vajtai, L. Xu, P.-G. Ren, J.-H. Wang, Z.-M. Li, Structured Reduced Graphene Oxide/Polymer Composites for Ultra-Efficient Electromagnetic Interference Shielding. Adv. Funct. Mater. 25, 559–566 (2015). doi:10.1002/adfm.201403809

3. N. Yousefi, X. Sun, X. Lin, X. Shen, J. Jia, B. Zhang, B. Tang, M. Chan, J. K. Kim, Highly aligned graphene/polymer nanocomposites with excellent dielectric properties for high-performance electromagnetic interference shielding. Adv. Mater. 26, 5480–5487 (2014). Medline doi:10.1002/adma.201305293

4. Y. Zhang, Y. Huang, T. Zhang, H. Chang, P. Xiao, H. Chen, Z. Huang, Y. Chen, Broadband and tunable high-performance microwave absorption of an ultralight and highly compressible graphene foam. Adv. Mater. 27, 2049–2053 (2015). Medline doi:10.1002/adma.201405788

5. A. H. Frey, Headaches from cellular telephones: Are they real and what are the implications? Environ. Health Perspect. 106, 101–103 (1998). Medline doi:10.1289/ehp.98106101

6. D. D. L. Chung, Electromagnetic interference shielding effectiveness of carbon materials. Carbon 39, 279–285 (2001). doi:10.1016/S0008-6223(00)00184-6

7. N. C. Das, Y. Liu, K. Yang, W. Peng, S. Maiti, H. Wang, Single-walled carbon nanotube/poly (methyl methacrylate) composites for electromagnetic interference shielding. Polym. Eng. Sci. 49, 1627–1634 (2009). doi:10.1002/pen.21384

8. M. H. Al-Saleh, W. H. Saadeh, U. Sundararaj, EMI shielding effectiveness of carbon based nanostructured polymeric materials: A comparative study. Carbon 60, 146–156 (2013). doi:10.1016/j.carbon.2013.04.008

9. H. B. Zhang, Q. Yan, W. G. Zheng, Z. He, Z. Z. Yu, Tough graphene-polymer microcellular foams for electromagnetic interference shielding. ACS Appl. Mater. Interfaces 3, 918–924 (2011). Medline doi:10.1021/am200021v

10. J.-M. Thomassin, C. Jérôme, T. Pardoen, C. Bailly, I. Huynen, C. Detrembleur, Polymer/carbon based composites as electromagnetic interference (EMI) shielding materials. Mater. Sci. Eng. Rep. 74, 211–232 (2013). doi:10.1016/j.mser.2013.06.001

11. M.-S. Cao, X.-X. Wang, W.-Q. Cao, J. Yuan, Ultrathin graphene: Electrical properties and highly efficient electromagnetic interference shielding. J. Mater. Chem. C 3, 6589–6599 (2015). doi:10.1039/C5TC01354B

12. M. Naguib, V. N. Mochalin, M. W. Barsoum, Y. Gogotsi, 25th anniversary article: MXenes: a new family of two-dimensional materials. Adv. Mater. 26, 992–1005 (2014). Medline doi:10.1002/adma.201304138

13. M. R. Lukatskaya, O. Mashtalir, C. E. Ren, Y. Dall’Agnese, P. Rozier, P. L. Taberna, M. Naguib, P. Simon, M. W. Barsoum, Y. Gogotsi, Cation intercalation and high volumetric

14

capacitance of two-dimensional titanium carbide. Science 341, 1502–1505 (2013). Medline doi:10.1126/science.1241488

14. B. Anasori, Y. Xie, M. Beidaghi, J. Lu, B. C. Hosler, L. Hultman, P. R. Kent, Y. Gogotsi, M. W. Barsoum, Two-dimensional, ordered, double transition metals carbides (MXenes). ACS Nano 9, 9507–9516 (2015). Medline doi:10.1021/acsnano.5b03591

15. J. Halim, S. Kota, M. R. Lukatskaya, M. Naguib, M.-Q. Zhao, E. J. Moon, J. Pitock, J. Nanda, S. J. May, Y. Gogotsi, M. W. Barsoum, Synthesis and characterization of 2D molybdenum carbide (MXene). Adv. Funct. Mater. 26, 3118–3127 (2016). doi:10.1002/adfm.201505328

16. Z. Ling, C. E. Ren, M. Q. Zhao, J. Yang, J. M. Giammarco, J. Qiu, M. W. Barsoum, Y. Gogotsi, Flexible and conductive MXene films and nanocomposites with high capacitance. Proc. Natl. Acad. Sci. U.S.A. 111, 16676–16681 (2014). Medline doi:10.1073/pnas.1414215111

17. M. Boota, B. Anasori, C. Voigt, M. Q. Zhao, M. W. Barsoum, Y. Gogotsi, Pseudocapacitive Electrodes produced by oxidant-free polymerization of pyrrole between the layers of 2D titanium carbide (MXene). Adv. Mater. 28, 1517–1522 (2016). Medline

18. I. Kovalenko, B. Zdyrko, A. Magasinski, B. Hertzberg, Z. Milicev, R. Burtovyy, I. Luzinov, G. Yushin, A major constituent of brown algae for use in high-capacity Li-ion batteries. Science 334, 75–79 (2011). Medline doi:10.1126/science.1209150

19. B. Anasori et al., Control of electronic properties of 2D carbides (MXenes) by manipulating their transition metal layers. Nanoscale Horizons 1, 227–234 (2016).

20. M. Khazaei, M. Arai, T. Sasaki, C.-Y. Chung, N. S. Venkataramanan, M. Estili, Y. Sakka, Y. Kawazoe, Novel Electronic and Magnetic Properties of two-dimensional transition metal carbides and nitrides. Adv. Funct. Mater. 23, 2185–2192 (2013). doi:10.1002/adfm.201202502

21. J. J. Liang, Y. Wang, Y. Huang, Y. Ma, Z. Liu, J. Cai, C. Zhang, H. Gao, Y. Chen, Electromagnetic interference shielding of graphene/epoxy composites. Carbon 47, 922–925 (2009). doi:10.1016/j.carbon.2008.12.038

22. F. Shahzad, P. Kumar, Y.-H. Kim, S. M. Hong, C. M. Koo, Biomass-derived thermally annealed interconnected sulfur-doped graphene as a shield against electromagnetic interference. ACS Appl. Mater. Interfaces 8, 9361–9369 (2016). doi:10.1021/acsami.6b00418

23. Z. Zeng, M. Chen, H. Jin, W. Li, X. Xue, L. Zhou, Y. Pei, H. Zhang, Z. Zhang, Thin and flexible multi-walled carbon nanotube/waterborne polyurethane composites with high-performance electromagnetic interference shielding. Carbon 96, 768–777 (2016). doi:10.1016/j.carbon.2015.10.004

24. S. Varshney, A. Ohlan, V. K. Jain, V. P. Dutta, S. K. Dhawan, In situ synthesis of polypyrrole-γ-Fe2O3-Fly ash nanocomposites for protection against EMI pollution. Ind. Eng. Chem. Res. 53, 14282–14290 (2014). doi:10.1021/ie500512d

15

25. P. Xu, X. Han, C. Wang, H. Zhao, J. Wang, X. Wang, B. Zhang, Synthesis of electromagnetic functionalized barium ferrite nanoparticles embedded in polypyrrole. J. Phys. Chem. B 112, 2775–2781 (2008). Medline doi:10.1021/jp710259v

26. L. Liu, Z. H. Yang, C. R. Deng, Z. W. Li, M. A. Abshinova, L. B. Kong, High frequency properties of composite membrane with in-plane aligned Sendust flake prepared by infiltration method. J. Magn. Magn. Mater. 324, 1786–1790 (2012). doi:10.1016/j.jmmm.2011.12.038

27. A. Ameli, M. Nofar, S. Wang, C. B. Park, Lightweight polypropylene/stainless-steel fiber composite foams with low percolation for efficient electromagnetic interference shielding. ACS Appl. Mater. Interfaces 6, 11091–11100 (2014). Medline doi:10.1021/am500445g

28. B. Shen, Y. Li, W. Zhai, W. Zheng, Compressible graphene-coated polymer foams with ultra-low density for adjustable EMI shielding. ACS Appl. Mater. Interfaces 8, 8050–8057 (2016).doi:10.1021/acsami.5b11715

29. Y. Yang, M. C. Gupta, K. L. Dudley, R. W. Lawrence, Novel carbon nanotube-polystyrene foam composites for electromagnetic interference shielding. Nano Lett. 5, 2131–2134 (2005). Medline doi:10.1021/nl051375r

30. Y. Chen, H.-B. Zhang, Y. Yang, M. Wang, A. Cao, Z.-Z. Yu, High-performance epoxy nanocomposites reinforced with three-dimensional carbon nanotube sponge for electromagnetic interference shielding. Adv. Funct. Mater. 26, 447–455 (2016). doi:10.1002/adfm.201503782

31. Z. Zeng, H. Jin, M. Chen, W. Li, L. Zhou, Z. Zhang, Lightweight and anisotropic porous MWCNT/WPU composites for ultrahigh performance electromagnetic interference shielding. Adv. Funct. Mater. 26, 303–310 (2016). doi:10.1002/adfm.201503579

32. B. Shen, W. Zhai, W. Zheng, Ultrathin flexible graphene film: An excellent thermal conducting material with efficient EMI shielding. Adv. Funct. Mater. 24, 4542–4548 (2014). doi:10.1002/adfm.201400079

33. M. Naguib, M. Kurtoglu, V. Presser, J. Lu, J. Niu, M. Heon, L. Hultman, Y. Gogotsi, M. W. Barsoum, Two-dimensional nanocrystals produced by exfoliation of Ti3AlC2. Adv. Mater. 23, 4248–4253 (2011). Medline doi:10.1002/adma.201102306

34. M. Ghidiu, M. R. Lukatskaya, M.-Q. Zhao, Y. Gogotsi, M. W. Barsoum, Conductive two-dimensional titanium carbide ‘clay’ with high volumetric capacitance. Nature 516, 78–81 (2014). Medline doi:10.1038/nature13970

35. K. Wenderoth, J. Petermann, K. D. Kruse, J. L. ter Haseborg, W. Krieger, Synergism on electromagnetic inductance (EMI)-shielding in metal-and ferroelectric-particle filled polymers. Polymer Composites 10, 52–56 (1989). doi:10.1002/pc.750100108

36. R. M. Simon, EMI shielding through conductive plastics. Polym.-Plastics Technol. Eng. 17, 1–10 (1981). doi:10.1080/03602558108067695

37. J. Ling, W. Zhai, W. Feng, B. Shen, J. Zhang, W. Zheng, Facile preparation of lightweight microcellular polyetherimide/graphene composite foams for electromagnetic interference

16

shielding. ACS Appl. Mater. Interfaces 5, 2677–2684 (2013). Medline doi:10.1021/am303289m

38. B. Wen, X. X. Wang, W. Q. Cao, H. L. Shi, M. M. Lu, G. Wang, H. B. Jin, W. Z. Wang, J. Yuan, M. S. Cao, Reduced graphene oxides: The thinnest and most lightweight materials with highly efficient microwave attenuation performances of the carbon world. Nanoscale 6, 5754–5761 (2014). Medline doi:10.1039/c3nr06717c

39. B. Yuan, C. Bao, X. Qian, L. Song, Q. Tai, K. M. Liew, Y. Hu, Design of artificial nacre-like hybrid films as shielding to mitigate electromagnetic pollution. Carbon 75, 178–189 (2014). doi:10.1016/j.carbon.2014.03.051

40. S.-T. Hsiao, C. C. Ma, W. H. Liao, Y. S. Wang, S. M. Li, Y. C. Huang, R. B. Yang, W. F. Liang, Lightweight and flexible reduced graphene oxide/water-borne polyurethane composites with high electrical conductivity and excellent electromagnetic interference shielding performance. ACS Appl. Mater. Interfaces 6, 10667–10678 (2014). Medline doi:10.1021/am502412q

41. D.-X. Yan, P.-G. Ren, H. Pang, Q. Fu, M.-B. Yang, Z.-M. Li, Efficient electromagnetic interference shielding of lightweight graphene/polystyrene composite. J. Mater. Chem. 22, 18772–18774 (2012). doi:10.1039/c2jm32692b

42. B. Yuan, L. Yu, L. Sheng, K. An, X. Zhao, Comparison of electromagnetic interference shielding properties between single-wall carbon nanotube and graphene sheet/polyaniline composites. J. Phys. D Appl. Phys. 45, 235108 (2012). doi:10.1088/0022-3727/45/23/235108

43. F. Shahzad, S. Yu, P. Kumar, J.-W. Lee, Y.-H. Kim, S. M. Hong, C. M. Koo, Sulfur doped graphene/polystyrene nanocomposites for electromagnetic interference shielding. Compos. Struct. 133, 1267–1275 (2015). doi:10.1016/j.compstruct.2015.07.036

44. S. Umrao, T. K. Gupta, S. Kumar, V. K. Singh, M. K. Sultania, J. H. Jung, I. K. Oh, A. Srivastava, Microwave-assisted synthesis of boron and nitrogen co-doped reduced graphene oxide for the protection of electromagnetic radiation in Ku-band. ACS Appl. Mater. Interfaces 7, 19831–19842 (2015). Medline doi:10.1021/acsami.5b05890

45. P. Tripathi, C. R. Prakash Patel, A. Dixit, A. P. Singh, P. Kumar, M. A. Shaz, R. Srivastava, G. Gupta, S. K. Dhawan, B. K. Gupta, O. N. Srivastava, High yield synthesis of electrolyte heating assisted electrochemically exfoliated graphene for electromagnetic interference shielding applications. RSC Adv. 5, 19074–19081 (2015). doi:10.1039/C4RA17230B

46. L. Zhang, N. T. Alvarez, M. Zhang, M. Haase, R. Malik, D. Mast, V. Shanov, Preparation and characterization of graphene paper for electromagnetic interference shielding. Carbon 82, 353–359 (2015). doi:10.1016/j.carbon.2014.10.080

47. P. Kumar, F. Shahzad, S. Yu, S. M. Hong, Y.-H. Kim, C. M. Koo, Large-area reduced graphene oxide thin film with excellent thermal conductivity and electromagnetic interference shielding effectiveness. Carbon 94, 494–500 (2015). doi:10.1016/j.carbon.2015.07.032

17

48. B. Shen, Y. Li, D. Yi, W. Zhai, X. Wei, W. Zheng, Microcellular graphene foam for improved broadband electromagnetic interference shielding. Carbon 102, 154–160 (2016). doi:10.1016/j.carbon.2016.02.040

49. A. P. Singh, M. Mishra, P. Sambyal, B. K. Gupta, B. P. Singh, A. Chandra, S. K. Dhawan, Encapsulation of γ-Fe2O3 decorated reduced graphene oxide in polyaniline core-shell tubes as an exceptional tracker for electromagnetic environmental pollution. J. Mater. Chem. A 2, 3581–3593 (2014). doi:10.1039/C3TA14212D

50. B. V. B. Rao, P. Yadav, R. Aepuru, H. S. Panda, S. Ogale, S. N. Kale, Single-layer graphene-assembled 3D porous carbon composites with PVA and Fe₃O₄ nano-fillers: An interface-mediated superior dielectric and EMI shielding performance. Phys. Chem. Chem. Phys. 17, 18353–18363 (2015). Medline doi:10.1039/C5CP02476E

51. K. Singh, A. Ohlan, V. H. Pham, B. R, S. Varshney, J. Jang, S. H. Hur, W. M. Choi, M. Kumar, S. K. Dhawan, B. S. Kong, J. S. Chung, Nanostructured graphene/Fe₃O₄ incorporated polyaniline as a high performance shield against electromagnetic pollution. Nanoscale 5, 2411–2420 (2013). Medline doi:10.1039/c3nr33962a

52. A. P. Singh, P. Garg, F. Alam, K. Singh, R. B. Mathur, R. P. Tandon, A. Chandra, S. K. Dhawan, Phenolic resin-based composite sheets filled with mixtures of reduced graphene oxide, γ-Fe2O3 and carbon fibers for excellent electromagnetic interference shielding in the X-band. Carbon 50, 3868–3875 (2012). doi:10.1016/j.carbon.2012.04.030

53. K. Yao, J. Gong, N. Tian, Y. Lin, X. Wen, Z. Jiang, H. Na, T. Tang, Flammability properties and electromagnetic interference shielding of PVC/graphene composites containing Fe3O4 nanoparticles. RSC Adv. 5, 31910–31919 (2015). doi:10.1039/C5RA01046B

54. B. Shen, W. Zhai, M. Tao, J. Ling, W. Zheng, Lightweight, multifunctional polyetherimide/graphene@Fe3O4 composite foams for shielding of electromagnetic pollution. ACS Appl. Mater. Interfaces 5, 11383–11391 (2013). Medline doi:10.1021/am4036527

55. T. K. Gupta, B. P. Singh, V. N. Singh, S. Teotia, A. P. Singh, I. Elizabeth, S. R. Dhakate, S. K. Dhawan, R. B. Mathur, MnO2 decorated graphene nanoribbons with superior permittivity and excellent microwave shielding properties. J. Mater. Chem. A 2, 4256–4263 (2014). doi:10.1039/c3ta14854h

56. W.-L. Song, X.-T. Guan, L.-Z. Fan, W.-Q. Cao, C.-Y. Wang, Q.-L. Zhao, M.-S. Cao, Magnetic and conductive graphene papers toward thin layers of effective electromagnetic shielding. J. Mater. Chem. A 3, 2097–2107 (2015). doi:10.1039/C4TA05939E

57. M. Mishra, A. P. Singh, B. P. Singh, V. N. Singh, S. K. Dhawan, Conducting ferrofluid: A high-performance microwave shielding material. J. Mater. Chem. A 2, 13159–13168 (2014). doi:10.1039/C4TA01681E

58. Q. Yuchang, W. Qinlong, L. Fa, Z. Wancheng, Z. Dongmei, Graphene nanosheets/BaTiO3 ceramics as highly efficient electromagnetic interference shielding materials in the X-band. J. Mater. Chem. C 4, 371–375 (2016). doi:10.1039/C5TC03035H

59. M. Verma, A. P. Singh, P. Sambyal, B. P. Singh, S. K. Dhawan, V. Choudhary, Barium ferrite decorated reduced graphene oxide nanocomposite for effective electromagnetic

18

interference shielding. Phys. Chem. Chem. Phys. 17, 1610–1618 (2015). Medline doi:10.1039/C4CP04284K

60. A. P. Singh, M. Mishra, D. P. Hashim, T. N. Narayanan, M. G. Hahm, P. Kumar, J. Dwivedi, G. Kedawat, A. Gupta, B. P. Singh, A. Chandra, R. Vajtai, S. K. Dhawan, P. M. Ajayan, B. K. Gupta, Probing the engineered sandwich network of vertically aligned carbon nanotube–reduced graphene oxide composites for high performance electromagnetic interference shielding applications. Carbon 85, 79–88 (2015). doi:10.1016/j.carbon.2014.12.065

61. S. Kuester, C. Merlini, G. M. O. Barra, J. C. Ferreira Jr., A. Lucas, A. C. de Souza, B. G. Soares, Processing and characterization of conductive composites based on poly(styrene-b-ethylene-ran-butylene-b-styrene) (SEBS) and carbon additives: A comparative study of expanded graphite and carbon black. Compos., Part B Eng. 84, 236–247 (2016). doi:10.1016/j.compositesb.2015.09.001

62. Q. J. Krueger, J. A. King, Synergistic effects of carbon fillers on shielding effectiveness in conductive nylon 6,6- and polycarbonate-based resins. Adv. Polym. Technol. 22, 96–111 (2003). doi:10.1002/adv.10040

63. X. Jiang, D.-X. Yan, Y. Bao, H. Pang, X. Ji, Z.-M. Li, Facile, green and affordable strategy for structuring natural graphite/polymer composite with efficient electromagnetic interference shielding. RSC Adv. 5, 22587–22592 (2015). doi:10.1039/C4RA11332B

64. V. Panwar, R. M. Mehra, Analysis of electrical, dielectric, and electromagnetic interference shielding behavior of graphite filled high density polyethylene composites. Polym. Eng. Sci. 48, 2178–2187 (2008). doi:10.1002/pen.21163

65. G. De Bellis, A. Tamburrano, A. Dinescu, M. L. Santarelli, M. S. Sarto, Electromagnetic properties of composites containing graphite nanoplatelets at radio frequency. Carbon 49, 4291–4300 (2011). doi:10.1016/j.carbon.2011.06.008

66. V. K. Sachdev, K. Patel, S. Bhattacharya, R. P. Tandon, Electromagnetic interference shielding of graphite/acrylonitrile butadiene styrene composites. J. Appl. Polym. Sci. 120, 1100–1105 (2011). doi:10.1002/app.33248

67. L.-L. Wang, B.-K. Tay, K.-Y. See, Z. Sun, L.-K. Tan, D. Lua, Electromagnetic interference shielding effectiveness of carbon-based materials prepared by screen printing. Carbon 47, 1905–1910 (2009). doi:10.1016/j.carbon.2009.03.033

68. H. M. Kim, K. Kim, C. Y. Lee, J. Joo, S. J. Cho, H. S. Yoon, D. A. Pejaković, J. W. Yoo, A. J. Epstein, Electrical conductivity and electromagnetic interference shielding of multiwalled carbon nanotube composites containing Fe catalyst. Appl. Phys. Lett. 84, 589–591 (2004). doi:10.1063/1.1641167

69. M. Farukh, A. P. Singh, S. K. Dhawan, Enhanced electromagnetic shielding behavior of multi-walled carbon nanotube entrenched poly (3,4-ethylenedioxythiophene) nanocomposites. Compos. Sci. Technol. 114, 94–102 (2015). doi:10.1016/j.compscitech.2015.04.004

70. A. Gupta, V. Choudhary, Electromagnetic interference shielding behavior of poly(trimethylene terephthalate)/multi-walled carbon nanotube composites. Compos. Sci. Technol. 71, 1563–1568 (2011). doi:10.1016/j.compscitech.2011.06.014

19

71. Y. Huang, N. Li, Y. Ma, F. Du, F. Li, X. He, X. Lin, H. Gao, Y. Chen, The influence of single-walled carbon nanotube structure on the electromagnetic interference shielding efficiency of its epoxy composites. Carbon 45, 1614–1621 (2007). doi:10.1016/j.carbon.2007.04.016

72. Z. Liu, G. Bai, Y. Huang, Y. Ma, F. Du, F. Li, T. Guo, Y. Chen, Reflection and absorption contributions to the electromagnetic interference shielding of single-walled carbon nanotube/polyurethane composites. Carbon 45, 821–827 (2007). doi:10.1016/j.carbon.2006.11.020

73. A. Chaudhary, S. Kumari, R. Kumar, S. Teotia, B. P. Singh, A. P. Singh, S. K. Dhawan, S. R. Dhakate, Lightweight and easily foldable MCMB-MWCNTs composite paper with exceptional electromagnetic interference shielding. ACS Appl. Mater. Interfaces 8, 10600–10608 (2016). Medline doi:10.1021/acsami.5b12334

74. M. Crespo, N. Méndez, M. González, J. Baselga, J. Pozuelo, Synergistic effect of magnetite nanoparticles and carbon nanofibres in electromagnetic absorbing composites. Carbon 74, 63–72 (2014). doi:10.1016/j.carbon.2014.02.082

75. M. Bayat, H. Yang, F. K. Ko, D. Michelson, A. Mei, Electromagnetic interference shielding effectiveness of hybrid multifunctional Fe3O4/carbon nanofiber composite. Polymer (Guildf.) 55, 936–943 (2014). doi:10.1016/j.polymer.2013.12.042

76. L. Li, D. D. L. Chung, Electrical and mechanical properties of electrically conductive polyethersulfone composites. Composites 25, 215–224 (1994). doi:10.1016/0010-4361(94)90019-1

77. B. Lee, W. J. Woo, H. S. Park, H. S. Hahm, J. P. Wu, M. S. Kim, Influence of aspect ratio and skin effect on EMI shielding of coating materials fabricated with carbon nanofiber/PVDF. J. Mater. Sci. 37, 1839–1843 (2002). doi:10.1023/A:1014970528482

78. A. Ameli, P. U. Jung, C. B. Park, Electrical properties and electromagnetic interference shielding effectiveness of polypropylene/carbon fiber composite foams. Carbon 60, 379–391 (2013). doi:10.1016/j.carbon.2013.04.050

79. Y. Yang, M. C. Gupta, K. L. Dudley, R. W. Lawrence, Conductive carbon nanofiber–polymer foam structures. Adv. Mater. 17, 1999–2003 (2005). doi:10.1002/adma.200500615

80. Y. Yang, M. C. Gupta, K. L. Dudley, Towards cost-efficient EMI shielding materials using carbon nanostructure-based nanocomposites. Nanotechnology 18, 345701 (2007). doi:10.1088/0957-4484/18/34/345701

81. W.-L. Song, J. Wang, L. Z. Fan, Y. Li, C. Y. Wang, M. S. Cao, Interfacial engineering of carbon nanofiber-graphene-carbon nanofiber heterojunctions in flexible lightweight electromagnetic shielding networks. ACS Appl. Mater. Interfaces 6, 10516–10523 (2014). Medline doi:10.1021/am502103u

82. F. El-Tantawy, N. A. Aal, Y. K. Sung, New functional conductive polymer composites containing nickel coated carbon black reinforced phenolic resin. Macromol. Res. 13, 194–205 (2005). doi:10.1007/BF03219052

20

83. H. Gargama, A. K. Thakur, S. K. Chaturvedi, Polyvinylidene fluoride/nickel composite materials for charge storing, electromagnetic interference absorption, and shielding applications. J. Appl. Phys. 117, 224903 (2015). doi:10.1063/1.4922411

84. X. Shui, D. D. L. Chung, Nickel filament polymer-matrix composites with low surface impedance and high electromagnetic interference shielding effectiveness. J. Electron. Mater. 26, 928–934 (1997). doi:10.1007/s11664-997-0276-4

85. X. Huang, B. Dai, Y. Ren, J. Xu, P. Zhu, Preparation and study of electromagnetic interference shielding materials comprised of ni-co coated on web-like biocarbon nanofibers via electroless deposition. J. Nanomater. 2015, 320306 (2015). doi:10.1155/2015/320306

86. J. Li, S. Qi, M. Zhang, Z. Wang, Thermal conductivity and electromagnetic shielding effectiveness of composites based on Ag-plating carbon fiber and epoxy. J. Appl. Polym. Sci. 132, 42306 (2015).

87. N. M. Abbasi, H. Yu, L. Wang, Zain-ul-Abdin, W. A. Amer, M. Akram, H. Khalid, Y. Chen, M. Saleem, R. Sun, J. Shan, Preparation of silver nanowires and their application in conducting polymer nanocomposites. Mater. Chem. Phys. 166, 1–15 (2015). doi:10.1016/j.matchemphys.2015.08.056

88. F. Fang, Y.-Q. Li, H.-M. Xiao, N. Hu, S.-Y. Fu, Layer-structured silver nanowire/polyaniline composite film as a high performance X-band EMI shielding material. J. Mater. Chem. C 4, 4193–4203 (2016). doi:10.1039/C5TC04406E

89. M. Arjmand, A. A. Moud, Y. Li, U. Sundararaj, Outstanding electromagnetic interference shielding of silver nanowires: Comparison with carbon nanotubes. RSC Adv. 5, 56590–56598 (2015). doi:10.1039/C5RA08118A

90. A. A. Al-Ghamdi, F. El-Tantawy, New electromagnetic wave shielding effectiveness at microwave frequency of polyvinyl chloride reinforced graphite/copper nanoparticles. Compos., Part A Appl. Sci. Manuf. 41, 1693–1701 (2010). doi:10.1016/j.compositesa.2010.08.006

91. M. H. Al-Saleh, G. A. Gelves, U. Sundararaj, Copper nanowire/polystyrene nanocomposites: Lower percolation threshold and higher EMI shielding. Compos. Part A Appl. Sci. Manuf. 42, 92–97 (2011). doi:10.1016/j.compositesa.2010.10.003

92. X. Luo, D. D. L. Chung, Electromagnetic interference shielding reaching 130 dB using flexible graphite. Carbon 34, 1293–1294 (1996). doi:10.1016/0008-6223(96)82798-9

93. L. Zhang, M. Liu, S. Roy, E. K. Chu, K. Y. See, X. Hu, Phthalonitrile-based carbon foam with high specific mechanical strength and superior electromagnetic interference shielding performance. ACS Appl. Mater. Interfaces 8, 7422–7430 (2016). Medline doi:10.1021/acsami.5b12072

94. F. Moglie, D. Micheli, S. Laurenzi, M. Marchetti, V. Mariani Primiani, Electromagnetic shielding performance of carbon foams. Carbon 50, 1972–1980 (2012). doi:10.1016/j.carbon.2011.12.053

21

95. Q. Wen, W. Zhou, J. Su, Y. Qing, F. Luo, D. Zhu, High performance electromagnetic interference shielding of lamellar MoSi2/glass composite coatings by plasma spraying. J. Alloys Compd. 666, 359–365 (2016). doi:10.1016/j.jallcom.2016.01.123

96. M.-Q. Ning, M. M. Lu, J. B. Li, Z. Chen, Y. K. Dou, C. Z. Wang, F. Rehman, M. S. Cao, H. B. Jin, Two-dimensional nanosheets of MoS2: A promising material with high dielectric properties and microwave absorption performance. Nanoscale 7, 15734–15740 (2015). Medline doi:10.1039/C5NR04670J

97. B. Wen, M. Cao, M. Lu, W. Cao, H. Shi, J. Liu, X. Wang, H. Jin, X. Fang, W. Wang, J. Yuan, Reduced graphene oxides: Light-weight and high-efficiency electromagnetic interference shielding at elevated temperatures. Adv. Mater. 26, 3484–3489 (2014). Medline doi:10.1002/adma.201400108

98. B.-W. Li, Y. Shen, Z.-X. Yue, C.-W. Nan, Enhanced microwave absorption in nickel/hexagonal-ferrite/polymer composites. Appl. Phys. Lett. 89, 132504 (2006). doi:10.1063/1.2357565

99. K. Singh, A. Ohlan, P. Saini, S. K. Dhawan, Poly (3,4-ethylenedioxythiophene) γ-Fe2O3 polymer composite–super paramagnetic behavior and variable range hopping 1D conduction mechanism–synthesis and characterization. Polym. Adv. Technol. 19, 229–236 (2008). doi:10.1002/pat.1003

100. A. Ohlan, K. Singh, A. Chandra, S. K. Dhawan, Microwave absorption behavior of core-shell structured poly (3,4-ethylenedioxy thiophene)-barium ferrite nanocomposites. ACS Appl. Mater. Interfaces 2, 927–933 (2010). Medline doi:10.1021/am900893d

101. Y.-Q. Li, Y. A. Samad, K. Polychronopoulou, K. Liao, Lightweight and highly conductive aerogel-like carbon from sugarcane with superior mechanical and EMI shielding properties. ACS Sustain. Chem. Eng. 3, 1419–1427 (2015). doi:10.1021/acssuschemeng.5b00340

102. Y. Li, R. Yi, A. Yan, L. Deng, K. Zhou, X. Liu, Facile synthesis and properties of ZnFe2O4 and ZnFe2O4/polypyrrole core-shell nanoparticles. Solid State Sci. 11, 1319–1324 (2009). doi:10.1016/j.solidstatesciences.2009.04.014

103. S. H. Hosseini, A. Asadnia, Synthesis, characterization, and microwave-absorbing properties of polypyrrole/MnFe2O4 nanocomposite. J. Nanomater. 2012, 198973 (2012). doi:10.1155/2012/198973

104. H. Xiao, W. Yuan-Sheng, Studies on the synthesis and microwave absorption properties of Fe3O4/polyaniline FGM. Phys. Scr. 2007, 335 (2007).

105. M. Sui, X. Lü, A. Xie, W. Xu, X. Rong, G. Wu, The synthesis of three-dimensional (3D) polydopamine-functioned carbonyl iron powder@polypyrrole (CIP@PPy) aerogel composites for excellent microwave absorption. Synth. Met. 210, 156–164 (2015). doi:10.1016/j.synthmet.2015.09.025

106. Y. Li, X. Pei, B. Shen, W. Zhai, L. Zhang, W. Zheng, Polyimide/graphene composite foam sheets with ultrahigh thermostability for electromagnetic interference shielding. RSC Adv. 5, 24342–24351 (2015). doi:10.1039/C4RA16421K

22

107. K. Ji, H. Zhao, J. Zhang, J. Chen, Z. Dai, Fabrication and electromagnetic interference shielding performance of open-cell foam of a Cu–Ni alloy integrated with CNTs. Appl. Surf. Sci. 311, 351–356 (2014). doi:10.1016/j.apsusc.2014.05.067

108. J. Ma, K. Wang, M. Zhan, A comparative study of structure and electromagnetic interference shielding performance for silver nanostructure hybrid polyimide foams. RSC Adv. 5, 65283–65296 (2015). doi:10.1039/C5RA09507G

109. N. Agnihotri, K. Chakrabarti, A. De, Highly efficient electromagnetic interference shielding using graphite nanoplatelet/poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) composites with enhanced thermal conductivity. RSC Adv. 5, 43765–43771 (2015). doi:10.1039/C4RA15674A

110. S. Pande, A. Chaudhary, D. Patel, B. P. Singh, R. B. Mathur, Mechanical and electrical properties of multiwall carbon nanotube/polycarbonate composites for electrostatic discharge and electromagnetic interference shielding applications. RSC Adv. 4, 13839–13849 (2014). doi:10.1039/c3ra47387b

111. M. Arjmand, T. Apperley, M. Okoniewski, U. Sundararaj, Comparative study of electromagnetic interference shielding properties of injection molded versus compression molded multi-walled carbon nanotube/polystyrene composites. Carbon 50, 5126–5134 (2012). doi:10.1016/j.carbon.2012.06.053

112. P. Ghosh, A. Chakrabarti, Conducting carbon black filled EPDM vulcanizates: Assessment of dependence of physical and mechanical properties and conducting character on variation of filler loading. Eur. Polym. J. 36, 1043–1054 (2000). doi:10.1016/S0014-3057(99)00157-3

23