Supporting Information

Fabrication of superelastic and highly conductive graphene aerogels by

precisely “unlocking” the oxygenated groups on graphene oxide sheets

Xiaoxiao Chen‡ a, Dengguo Lai‡ a, Baoling Yuan b, Ming-Lai Fu a, *

a CAS Key Laboratory of Urban Pollutant Conversion, Institute of Urban Environment,

Chinese Academy of Sciences, Xiamen, 361021, Chinab College of Civil Engineering, Huaqiao University, Xiamen, 361020, China

* Corresponding author.

E-mail address: mlfu@iue.ac.cn (M.-L. Fu).

‡ These authors contributed equally to this work.

1

Preparation of GO dispersion: GO was synthesized from natural powder graphite (99.85%,

Sinopharm) by a modified Hummers’ method.[1-2] First, weighted graphite powder (10 g) was

suspended in a solution of concentrated H2SO4 (40 mL) dissolved with K2S2O8 (8.33 g) and

P2O5 (8.33 g). After increasing the mixture temperature to 80 oC and keeping stirring for 4.5

h, the mixture was collected and rinsed with deionized water thoroughly until the pH became

neutral, dried at 60 oC to obtain pre-oxidized graphite. Next, 10 g pre-oxidized graphite was

re-suspended in concentrated H2SO4 (230 mL) with 5 g NaNO3 in an ice bash with stirring.

To keep the suspension at a low temperature (< 4 oC), 30 g KMnO4 was added slowly within

30 min. After that, the temperature was increased to 35 oC and kept for another 2 h. When

finished, the suspension became green and too thick to stir. Then 460 mL deionized water

was gradually added and the suspension was further stirred at 98 oC for 15 min then

terminated by adding another 460 mL deionized water and 25 mL 30% H2O2, leaving a

glittery gold suspension. To remove the residual SO42- and metal ions, the suspension

obtained was rinsed by 10 % HCl, followed by centrifugation at 8000 rpm until no SO42-

could be detected with BaCl2. The resulting solid was re-dispersed in deionized water and

peeled by ultra-sonication for 30 min, and subjected to dialysis to remove the acid and other

impurities for approximately one week. Brown sticky dispersion in its as-synthesized form

was labeled conventional graphene oxide (C-GO) nanosheets.

2

Figure S1. Schematic of the homemade apparatus used for unidirectional freeze casting of

PVA/C-GO and PVA/A-GO dispersion.

Figure S2. Photographs of hydrogels obtained with suspensions containing 1, 2, and 3 mg

mL-1 GO (with fixed GO: PVA mass ratio of 1:1).

3

Figure S3. SEM images of (a, b) A-GO, and (c, d) C-GO sheets.

4

Figure S4. Typical top-view SEM images of (a-d) PA-GA, and (e, f) PC-GA at different

magnifications.

5

Figure S5. Typical top-view SEM images of (a-d) TA-GA, and (e, f) TC-GA after thermal-

treatment at different magnifications.

6

Figure S6. (a) TGA data of C-GO, A-GO, PC-GA and PA-GA, and (b) their PVA contents

calculated.

The residual weight of pure aerogels, PVA/graphene aerogels composites and PVA polymer

at 700 oC are estimated to be 80.54%, 74.97%, 50.73%, 48.69% and 15.34%, respectively.

The mass composition of PVA in PA-GA is calculated as follow: PVA content% = (80.54%-

50.73%) / (80.54%-15.34%) × 100 = 45.7%; similarly, the mass composition of PVA in PC-

GA: PVA content% = (74.97%-48.69%) / (74.97%-15.34%) × 100 = 44.1%.

7

Figure S7. XRD spectrums of TC-GA, TA-GA and graphite powder.

Figure S8. Raman spectra of pristine C-GO, A-GO and synthesized aerogels PC-GA, PA-

GA, TC-GA, and TA-GA.

Table S1. Distribution of C 1s species of C-GO, A-GO, PC-GA, PA-GA, TC-GA and TA-

GA, C/O atomic ratios calculated by XPS survey spectra, Ihydroxyl/Iepoxy calculated by FTIR

spectra, ID/IG calculated by Raman spectra, and PVA contents of PC-GA and PA-GA obtained

by TGA data.

C-GO A-GO PC-GA PA-GA TC-GA TA-GA

C

1s/%

C=C 34.97 45.47 46.59 52.75 67.40 66.19

C-O 43.94 38.55 26.52 30.79 15.00 16.00

C=O 18.41 12.80 22.39 12.84 6.74 7.55

O-

C=O

2.68 3.18 4.51 3.62 3.37 3.36

C/O atomic

ratio

3.06 3.57 3.18 3.41 51.18 50.87

Ihydroxyl/Iepoxy 1.01 1.40 \ \ \ \

ID/IG 1.045±0.00

7

1.094±0.00

8

0.987±0.02

1

1.096±0.00

1

0.869±0.02

3

0.950±0.008

8

PVA

content/%

\ \ 44.1 45.7 \ \

Figure S9. Digital images of TA-GA after 1000 compression cycles.

Figure S10. Cyclic stress-strain curves of TC-GA at 50% strain under (a) axial (Z) and (b)

radial compressions.

9

Table

S2.

Summary of n-hexane and chloroform absorption capacities of various carbon aerogels for

comparison with our work.

10

MaterialsQw

(g g-1)

n-Hexane

(g g-1)

Chlorofor

m (g g-1)Refs.

TA-GA 279.3-587.5 295.8 587.5 This

work

TC-GA 217.0-411.6 217.0 401.5 This

work

Silane-modified GA 407-1035 400 977 [3]

RGO/CNF aerogel 393-1002 390 820 [4]

Ultra-flyweight aerogel 215-743 215 550 [5]

Graphene aerogel bulk 220-560 \ 520 [6]

MWCNT-PDA/GA 125-525 ~225 ~525 [7]

GA (melamine foam as

sacrificial skeleton)

176-513 ~176 ~460 [8]

Superelastic GA 178-330 180 330 [9]

ultralight GA 134.0-282.9 ~160 282.9 [10]

PVA/GA 130-274 \ 274 [11]

CNT/RGO aerogel 120-320 140 265 [12]

rGO/SWCNT aerogel 100-140 135 \ [13]

EDA/GA 120-250 120 \ [14]

MOF/rGA 50-160 65 125 [15]

Graphene foam 50-110 \ 110 [16]

CNT/GA 100-270 ~110 \ [17]

GA 22-86 ~43 ~86 [18]

cellulose fibers aerogel 80-161 ~80 ~161 [19]

CNT sponge 89-175 ~89 ~175 [20]

Table S3. Comparison of the electrical conductivity and specific conductivity of various

carbon-based 3D architectures. I: pure graphene aerogels assembled by GO sheets; II:

graphene aerogels composites; III: other carbon aerogels; IV: graphene aerogels with perfect

graphene nanosheets assisted by chemical vapor deposition (CVD) or from nonoxidized

graphene flakes.

MaterialsDensity

(mg cm-3)

Conductivity

(S m-1)

Specific

conductivity

(S cm2 g-1)

Ref.

ITA-GA

1.73±0.0

617.1±2.2 98.8

This

workTC-GA

1.69±0.0

68.2±1.8 48.5

3D print grapheme lattices 10.16 81 79.7 [21]

1.58 11 69.6

NS-HGA

NS-GA

6.29 21.66 34.4 [22]

3.42 12.43 36.3

3D printed graphene

aerogel

31 74 23.9 [23]

60 198 33.0

123 278 22.6

6 4.5 7.5 [24]

8.5 9.5 11.2

11 13 11.9

16.2 23 14.2

N-doped rGO aerogels 2.32 11.74 50.6 [25]

GA 14.2 24.8 17.5 [26]

8 18.3 22.9

4.5 7.3 16.2

3.6 3.1 8.6

2.2 0.7 3.2

GA 5.1 12 23.5 [27]

11

GA 96 100 10.4 [28]

graphene sponge-radial 1.15 0.44 3.8 [29]

graphene sponge-axial 1.15 0.35 3.0

GA 6.73 0.48 0.71 [30]

8.6 0.75 0.87

12.32 1.76 1.4

UGA 0.9 4 44.4 [31]

2 10 50.0

3.5 17 48.6

II

PDA/rGO aerogels 8.7 13.289 15.3 [32]

CS/RGA series 17.3 65 37.6 [33]

11.2 75 67.0

GO-CNT aerogel 1.9 1.1 5.8 [34]

3.1 2.4 7.7

M-GS 5.8 0.122 0.21 [35]

RGO/PI aerogel 20 17 8.5 [36]

RGO/CNF aerogel series 1.75 10 57.1 [4]

1.9 16 84.2

4.5 47 104.4

8.33 98 117.6

AAm/GA series 4.8 12.3 25.6 [37]

Fe3O4/GA 5.8 34.8 60.0 [38]

GA/PI 10 0.022 0.022 [39]

GPA 1.8 0.015 0.083 [40]

6.9 0.043 0.062

14.2 0.57 0.40

27.2 1 0.37

PVA/GA 6.5 2.8 4.3 [41]

CS-GA 14.1 6.7 4.8 [42]

CF/GA 2.83 15.93 56.3 [43]

12

Silane-b-RGO 11.1 0.69 0.63 [44]

16.5 0.24 0.15

41.1 0.08 0.020

12.5 0.98 0.78

23 23 10.0

III

Pectin/PANI aerogel 80 0.002 0.00025 [45]

Pectin/PANI aerogel 110 0.02 0.0018

Pectin/PANI aerogel 110 0.1 0.0091

Catkins carbon aerogel 21.5 47 21.7 [19]

IV

graphene/Al2O3 ceramic

aerogel

10 102 102.0 [46]

GA-Graphene Nanosheets 48.2 1000 207.5 [47]

Nonoxidized

graphene/PVA aerogel

5.7 202.9 356.0 [48]

13

Figure S10. I-V curves of TA-GA under different pressures.

References

[1]. Hummers, W. S.; Offeman, R. E., Preparation of graphitic oxide. J. Am. Chem. Soc. 1958,

80, 1339.

[2]. Chen, X.; Lai, D.; Yuan, B.; Fu, M.-L., Tuning oxygen clusters on graphene oxide to

synthesize graphene aerogels with crumpled nanosheets for effective removal of organic

pollutants. Carbon 2019, 143, 897-907.

[3]. Xiao, J.; Tan, Y.; Song, Y.; Zheng, Q., A flyweight and superelastic graphene aerogel as a

high-capacity adsorbent and highly sensitive pressure sensor. J. Mater. Chem. A 2018, 6 (19),

14

9074-9080.

[4]. Li, C.; Wu, Z. Y.; Liang, H. W.; Chen, J. F.; Yu, S. H., Ultralight Multifunctional Carbon-

Based Aerogels by Combining Graphene Oxide and Bacterial Cellulose. Small 2017, 13 (25),

1700453-1-1700453-8.

[5]. Sun, H.; Xu, Z.; Gao, C., Multifunctional, ultra-flyweight, synergistically assembled carbon

aerogels. Adv. Mater. 2013, 25 (18), 2554-2560.

[6]. Yang, H.; Li, Z.; Lu, B.; Gao, J.; Jin, X.; Sun, G., et al., Reconstruction of Inherent Graphene

Oxide Liquid Crystals for Large-Scale Fabrication of Structure-Intact Graphene Aerogel Bulk

toward Practical Applications. ACS nano 2018, 12 (11), 11407-11416.

[7]. Zhan, W.; Yu, S.; Gao, L.; Wang, F.; Fu, X.; Sui, G., et al., Bioinspired Assembly of Carbon

Nanotube into Graphene Aerogel with "cabbagelike" Hierarchical Porous Structure for Highly

Efficient Organic Pollutants Cleanup. ACS Appl. Mater. Interfaces 2018, 10 (1), 1093-1103.

[8]. Li, C.; Jiang, D.; Liang, H.; Huo, B.; Liu, C.; Yang, W. , et al., Superelastic and Arbitrary-

Shaped Graphene Aerogels with Sacrificial Skeleton of Melamine Foam for Varied

Applications. Adv. Funct. Mater. 2017, 1704674-1-1704674-9.

[9]. Li, Y.; Zhang, G.; Gao, A.; Cui, J.; Zhao, S.; Yan, Y., Robust Graphene/Poly(vinyl alcohol)

Janus Aerogels with a Hierarchical Architecture for Highly Efficient Switchable Separation of

Oil/Water Emulsions. ACS Appl. Mater. Interfaces 2019, 11 (40), 36638-36648.

[10]. Li, L.; Li, B.; Zhang, J., Dopamine-mediated fabrication of ultralight graphene

aerogels with low volume shrinkage. J. Mater. Chem. A 2016, 4 (2), 512-518.

[11]. Ye, S.; Liu, Y.; Feng, J., Low-Density, Mechanical Compressible, Water-Induced Self-

Recoverable Graphene Aerogels for Water Treatment. ACS Appl. Mater. Interfaces 2017, 9

(27), 22456-22464.

[12]. Wang, C.; Yang, S.; Ma, Q.; Jia, X.; Ma, P., Preparation of carbon

nanotubes/graphene hybrid aerogel and its application for the adsorption of organic

compounds. Carbon 2017, 118, 765-771.

[13]. Tan, D.; Zhao, J.; Gao, C.; Wang, H.; Chen, G.; Shi, D., Carbon Nanoparticle Hybrid

Aerogels: 3D Double-Interconnected Network Porous Microstructure, Thermoelectric, and

Solvent-Removal Functions. ACS Appl. Mater. Interfaces 2017, 9 (26), 21820-21828.

15

[14]. Li, J.; Li, J.; Meng, H.; Xie, S.; Zhang, B.; Li, L., et al., Ultra-light, compressible and fire-

resistant graphene aerogel as a highly efficient and recyclable absorbent for organic liquids.

J. Mater. Chem. A 2014, 2 (9), 2934–2941.

[15]. Eom, S.; Kang, D. W.; Kang, M.; Choe, J. H.; Kim, H.; Kim, D. W. , et al., Fine-tuning of

wettability in a single metal-organic framework via postcoordination modification and its

reduced graphene oxide aerogel for oil-water separation. Chem. Sci. 2019, 10 (9), 2663-

2669.

[16]. Li, Y.; Zhang, H. B.; Zhang, L.; Shen, B.; Zhai, W.; Yu, Z. Z., et al., One-Pot Sintering

Strategy for Efficient Fabrication of High-Performance and Multifunctional Graphene Foams.

ACS Appl. Mater. Interfaces 2017, 9 (15), 13323-13330.

[17]. Wan, W.; Zhang, R.; Li, W.; Liu, H.; Lin, Y.; Li, L., et al., Graphene-carbon nanotube

aerogel as an ultra-light, compressible and recyclable highly efficient absorbent for oil and

dyes. Environ. Sci.: Nano 2016, 3 (1), 107-113.

[18]. Bi, H.; Xie, X.; Yin, K.; Zhou, Y.; Wan, S.; He, L., et al., Spongy Graphene as a Highly

Efficient and Recyclable Sorbent for Oils and Organic Solvents. Adv. Funct. Mater. 2012, 22

(21), 4421-4425.

[19]. Li, L.; Hu, T.; Sun, H.; Zhang, J.; Wang, A., Pressure-Sensitive and Conductive Carbon

Aerogels from Poplars Catkins for Selective Oil Absorption and Oil/Water Separation. ACS

Appl. Mater. Interfaces 2017, 9 (21), 18001-18007.

[20]. Gui, X.; Wei, J.; Wang, K.; Cao, A.; Zhu, H.; Jia, Y., et al., Carbon nanotube sponges.

Adv. Mater. 2010, 22 (5), 617-621.

[21]. Zhang, Q.; Zhang, F.; Xu, X.; Zhou, C.; Lin, D., Three-Dimensional Printing Hollow

Polymer Template-Mediated Graphene Lattices with Tailorable Architectures and

Multifunctional Properties. ACS nano 2018, 12 (2), 1096-1106.

[22]. Kotal, M.; Kim, H.; Roy, S.; Oh, I.-K., Sulfur and nitrogen co-doped holey graphene

aerogel for structurally resilient solid-state supercapacitors under high compressions. J.

Mater. Chem. A 2017, 5 (33), 17253-17266.

[23]. Zhu, C.; Han, T. Y.-J.; Duoss, E. B.; Golobic, A. M.; Kuntz, J. D.; Spadaccini, C. M., et

al., Highly compressible 3D periodic graphene aerogel microlattices. Nat. Commun. 2015, 6,

16

6962-16962-8.

[24]. Wang, Z.; Shen, X.; Garakani, M. A.; Lin, X.; Wu, Y.; Liu, X., et al., Graphene

Aerogel/Epoxy Composites with Exceptional Anisotropic Structure and Properties. ACS Appl.

Mater. Interfaces 2015, 7 (9), 5538-5549.

[25]. Moon, I. K.; Yoon, S.; Chun, K.-Y.; Oh, J., Highly Elastic and Conductive N-Doped

Monolithic Graphene Aerogels for Multifunctional Applications. Adv. Funct. Mater. 2015, 25

(45), 6976-6984.

[26]. Zhang, L.; Chen, G.; Hedhili, M. N.; Zhang, H.; Wang, P., Three-dimensional

assemblies of graphene prepared by a novel chemical reduction-induced self-assembly

method. Nanoscale 2012, 4 (22), 7038-7045.

[27]. Qiu, L.; Liu, J. Z.; Chang, S. L.; Wu, Y.; Li, D., Biomimetic superelastic graphene-based

cellular monoliths. Nat. Commun. 2012, 3, 1241-1-1241-7.

[28]. Zhang, X.; Sui, Z.; Xu, B.; Yue, S.; Luo, Y.; Zhan, W., et al., Mechanically strong and

highly conductive graphene aerogel and its use as electrodes for electrochemical power

sources. J. Mater. Chem. 2011, 21 (18), 6494-6497.

[29]. Wu, Y.; Yi, N.; Huang, L.; Zhang, T.; Fang, S.; Chang, H., et al., Three-dimensionally

bonded spongy graphene material with super compressive elasticity and near-zero Poisson's

ratio. Nat. Commun. 2015, 6, 6141-16141-9.

[30]. Li, Y.; Chen, J.; Huang, L.; Li, C.; Hong, J.-D.; Shi, G., Highly Compressible

Macroporous Graphene Monoliths via an Improved Hydrothermal Process. Adv. Mater.

2014, 26 (28), 4789–4793.

[31]. Wang, Z.; Shen, X.; Han, N. M.; Liu, X.; Wu, Y.; Ye, W., et al., Ultralow Electrical

Percolation in Graphene Aerogel/Epoxy Composites. Chem. Mater. 2016, 28 (18), 6731-6741.

[32]. Wang, L.; Zhang, X.; He, Y.; Wang, Y.; Zhong, W.; Mequanint, K. , et al., Ultralight

Conductive and Elastic Aerogel for Skeletal Muscle Atrophy Regeneration. Adv. Funct. Mater.

2019, 29 (1), 1806200-1-1806200-17.

[33]. Zhang, Y.; Zhang, L.; Zhang, G.; Li, H., Naturally Dried Graphene-Based

Nanocomposite Aerogels with Exceptional Elasticity and High Electrical Conductivity. ACS

Appl. Mater. Interfaces 2018, 10 (25), 21565-21572.

17

[34]. Wu, X.; Liu, X.; Wang, J.; Huang, J.; Yang, S., Reducing Structural Defects and

Oxygen-Containing Functional Groups in GO-Hybridized CNTs Aerogels: Simultaneously

Improve the Electrical and Mechanical Properties To Enhance Pressure Sensitivity. ACS Appl.

Mater. Interfaces 2018, 10 (45), 39009-39017.

[35]. Liu, W.; Jiang, H.; Ru, Y.; Zhang, X.; Qiao, J., Conductive Graphene-Melamine Sponge

Prepared via Microwave Irradiation. ACS Appl. Mater. Interfaces 2018, 10 (29), 24776-24783.

[36]. Liu, J.; Liu, Y.; Zhang, H.-B.; Dai, Y.; Liu, Z.; Yu, Z.-Z., Superelastic and multifunctional

graphene-based aerogels by interfacial reinforcement with graphitized carbon at high

temperatures. Carbon 2018, 132, 95-103.

[37]. Li, C.; Qiu, L.; Zhang, B.; Li, D.; Liu, C.-Y., Robust Vacuum-/Air-Dried Graphene

Aerogels and Fast Recoverable Shape-Memory Hybrid Foams. Adv. Mater. 2016, 28 (7),

1510-1516.

[38]. Xu, X.; Li, H.; Zhang, Q.; Hu, H.; Zhao, Z.; Li, J. , et al., Self-Sensing, Ultra light, and

Conductive 3D Graphene/Iron Oxide Aerogel Elastomer Deformable in a Magnetic Field. ACS

nano 2015, 9 (4), 3969-3977.

[39]. Qin, Y.; Peng, Q.; Ding, Y.; Lin, Z.; Wang, C.; Li, Y., et al., Lightweight, Superelastic,

and Mechanically Flexible Graphene/Polyimide Nanocomposite Foam for Strain Sensor

Application. ACS nano 2015, 9 (9), 8933-8941.

[40]. Tang, G.; Jiang, Z.-G.; Li, X.; Zhang, H.-B.; Dasari, A.; Yu, Z.-Z., Three dimensional

graphene aerogels and their electrically conductive composites. Carbon 2014, 77, 592-599.

[41]. Yang, M.; Zhao, N.; Cui, Y.; Gao, W.; Zhao, Q.; Gao, C., et al., Biomimetic

Architectured Graphene Aerogel with Exceptional Strength and Resilience. ACS nano 2017,

11 (7), 6817-6824.

[42]. Gao, H. L.; Zhu, Y. B.; Mao, L. B.; Wang, F. C.; Luo, X. S.; Liu, Y. Y. , et al., Super-elastic

and fatigue resistant carbon material with lamellar multi-arch microstructure. Nat. Commun.

2016, 7, 12920-1-12920-8.

[43]. Wan, Y.-J.; Zhu, P.-L.; Yu, S.-H.; Sun, R.; Wong, C.-P.; Liao, W.-H., Ultralight, super-

elastic and volume-preserving cellulose fiber/graphene aerogel for high-performance

electromagnetic interference shielding. Carbon 2017, 115, 629-639.

18

[44]. Guan, L.-Z.; Gao, J.-F.; Pei, Y.-B.; Zhao, L.; Gong, L.-X.; Wan, Y.-J., et al., Silane bonded

graphene aerogels with tunable functionality and reversible compressibility. Carbon 2016,

107, 573-582.

[45]. Zhao, H.-B.; Yuan, L.; Fu, Z.-B.; Wang, C.-Y.; Yang, X.; Zhu, J.-Y., et al., Biomass-Based

Mechanically Strong and Electrically Conductive Polymer Aerogels and Their Application for

Supercapacitors. ACS Appl. Mater. Interfaces 2016, 8 (15), 9917-9924.

[46]. Zhang, Q.; Lin, D.; Deng, B.; Xu, X.; Nian, Q.; Jin, S., et al., Flyweight, Superelastic,

Electrically Conductive, and Flame-Retardant 3D Multi-Nanolayer Graphene/Ceramic

Metamaterial. Adv. Mater. 2017, 29 (28), 1605506-1-1605506-12.

[47]. Zhang, Q.; Wang, Y.; Zhang, B.; Zhao, K.; He, P.; Huang, B., 3D superelastic graphene

aerogel-nanosheet hybrid hierarchical nanostructures as high-performance supercapacitor

electrodes. Carbon 2018, 127, 449-458.

[48]. Kim, J.; Han, N. M.; Kim, J.; Lee, J.; Kim, J.-K.; Jeon, S., Highly Conductive and

Fracture-Resistant Epoxy Composite Based on Non-oxidized Graphene Flake Aerogel. ACS

Appl. Mater. Interfaces 2018, 10 (43), 37507-37516.

19