Effect of flake size on the mechanical properties of graphene aerogels prepared by freeze casting

Gao, Weiwei; Zhao, Nifang; Yao, Weiquan; Xu, Zhen; Bai, Hao; Gao, Chao

doi:10.1039/c7ra05557a

Cited by 61 publications

(40 citation statements)

References 40 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Additionally, several other methods report, GO could be reduced to reduced GO (rGO) and isolate as a monolayer by ascorbic acid (AA), where overall flake sizes are 10–60 μm [ 59 ]. GO monolayer could be isolated using a mixture of poly-vinyl alcohol and H 2 O mixture where flake sizes differ from 1–80 μm, although the size of the flakes would be controlled by duration of sonication as well as temperature at the time of sonication [ 60 ]. Further investigation is required to explore the ability of these solvents in isolating large planar GO flakes, and it is our next target in the future.…”

Section: Discussionmentioning

confidence: 99%

Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules

2021

View full text Add to dashboard Cite

In this manuscript, we report the application of graphene oxide (GO) in the preparation of cryo-electron microscopy (cryo-EM) and transmission electron microscopy (TEM) grids. We treated GO with water and organic solvents, such as, methanol, ethanol and isopropanol separately to isolate significantly large GO monolayer flake to fabricate the grids for cryo-EM and TEM study. We implemented a simplified approach to isolate flakes of GO monolayer for constructing the TEM grids, independent of expensive heavy equipment (Langmuir–Blodgett trough, glow-discharge system, carbon-evaporator or plasma-cleaner or peristaltic pumps). We employed confocal microscopy, SEM and TEM to characterize the flake size, stability and transparency of the GO monolayer and atomic force microscopy (AFM) to probe the depth of GO coated grids. Additionally, GO grids are visualized at cryogenic condition for suitability of GO monolayer for cryo-EM study. In addition, GO-Met-H2O grids reduce the effect of preferred orientation of biological macromolecules within the amorphous ice. The power-spectrum and contrast-transfer-function unequivocally suggest that GO-Met-H2O fabricated holey grids have excellent potential for application in high-resolution structural characterization of biomolecules. Furthermore, only 200 movies and ~8000 70S ribosome particles are selected on GO-coated grids for cryo-EM reconstruction to achieve high-resolution structure.

show abstract

Section: Discussionmentioning

confidence: 99%

Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules

2021

View full text Add to dashboard Cite

show abstract

“…Electrical conductivity of CRtTR300 (with t min chemical reduction and 300°C thermal reduction for 40 min at Ar atmosphere), CRtTR800 (with t min chemical reduction and 800°C thermal reduction for 40 min at Ar atmosphere) and rGO-EEG CRtTR800 (GO with electrically exfoliated graphene at t min chemical reduction and 800°C thermal reduction for 40 min at Ar atmosphere) (a) and compressive modulus of CRtTR300 samples (with t min chemical reduction and 300°C thermal reduction for 40 min at Ar atmosphere) developed in this work in comparison to literature values for other nanocarbon-based materials. Reduced-graphene cellular network [47], CNT foam [50], reduced graphene based aerogel [51], CVD graphene foam [52], graphene elastomer [16], 3D printed graphene [53], 3D graphene acroassembly [51], 3D printing graphene [48], GO aerogel [17], rGO-GNP hydrogel [54] and rGO aerogel [16,19,44,55].…”

Section: Discussionmentioning

confidence: 99%

Ice-templated hybrid graphene oxide—graphene nanoplatelet lamellar architectures: tuning mechanical and electrical properties

et al. 2021

View full text Add to dashboard Cite

The traditional freeze-casting route for processing graphene-based aerogels is generally restricted to aqueously dispersed flakes of graphene oxide (GO) and post-processing reduction treatments, which brings restrictions to the aerogels electrical properties. In this work, we report a versatile aqueous processing route that uses the ability of GO todisperse graphene nanoplatelets (GNP) to produce rGO-GNP lamellar aerogels via unidirectional freeze-casting. In order to optimise the properties of the aerogel, GO-GNP dispersions were partially reduced by L-ascorbic acid prior to freeze-casting to tune the carbon and oxygen (C/O) ratio. The aerogels were then heat treated after casting to fully reduce the GO. The chemical reduction time was found to control the microstructure of the resulting aeorgels and thus to tune their electrical and mechanical properties. An rGO-GNP lamellar aerogel with density of 20.8±0.8 mg cm −3 reducing using a reduction of 60 min achieved an electrical conductivity of 42.3 S m −1 . On the other hand, an optimal reduction time of 35 min led to an aerogel with compressive modulus of 0.51 ±0.06 MPa at a density of 23.2±0.7 mg cm −3 , revealing a compromise between the tuning of electrical and mechanical properties. We show the present processing route can also be easily applied to produce lamellar aerogels on other graphene-based materials such as electrochemically exfoliated graphene.

show abstract

“…4d) and GA (Fig. 4e), illustrating the bad mechanical strength, which are a common phenomenon for graphene based aerogel 48 . However, Cu@GA40 retained its shape integrity well, and no dreg was observed, owing to the protection of copper layer on its surface (Fig.…”

Section: Cu@gasmentioning

confidence: 96%

Fabrication of Three-Dimensional Copper@Graphene Phase Change Composite with High Structural Stability and Low Leakage Rate

李晓明¹,

高逸丹²,

孔庆强³

et al. 2021

Acta Physico Chimica Sinica

View full text Add to dashboard Cite

Owing to the continuous increase in energy consumption and the growing depletion of traditional fossil fuels, the development of renewable energy is becoming increasingly urgent. Renewable energy has come to the fore, represented by geothermal energy and solar energy. However, the application of these energy sources is highly susceptible to weather, season, location, and time. Thus, these alternative energies are unstable, random, fluctuating, intermittent, and inefficient. The development of energy storage technologies can efficiently solve these problems, storing and releasing energy when needed. Among the key materials used in various energy-storage technologies, phase-change materials (PCMs) are strong candidates for smart thermal energy management and portable thermal energy sectors. As most innate PCMs face issues of low thermal conductivity, environmental pollution, and leakage over their melting point, encapsulating PCMs into supporting materials is necessary. However, these supporting materials face significant challenges in their application. First, skeleton materials should be resistant to the PCM volume changes during melting and solidification processes to achieve suitable structural stability. Second, skeleton materials should also have high thermal conductivity and a low leakage rate. Graphene aerogel (GA) has proven to be an effective supporting skeleton to improve the shape-stability of PCMs; however, the leakage caused by the phase transition and the brittleness of the network structure is a primary problem restricting its application. Skeleton materials play a crucial role in the performance of PCMs. Herein, we propose a double-pulse plating reinforcement strategy for fabricating copper@graphene aerogel (Cu@GA) as a skeleton material for phase change energy. In this design, individual nanosheets of the GA were uniformly covered and interlinked by copper particles. The Cu@GA interlinked networks ensure suitable thermal conductivity and a robust framework, beneficial for phase change heat transfer and leaksuppression performance. In addition, we prepared a PCM composite with high structural stability and low leakage rate by encapsulating octadecylamine (ODA) in Cu@GA through vacuum impregnation to ensure homogeneous ODA dispersion in the Cu@GA porous structure. The influence of different skeletons on the PCM composite leakage rate was investigated by comparing the weight change of the PCM composite. Benefiting from these structural features, the optimized composite phase change material (CPCM) Cu@GA/ODA showed a reduced leakage rate of 19.82% (w, mass fraction) compared to 80.31% (w) of GA/ODA and 72.99% (w) of GOA/ODA after 20 heat storage and release cycles. The cycled skeleton morphology was investigated using scanning electron microscopy to determine the origin of this influence. The skeleton

show abstract

Effect of flake size on the mechanical properties of graphene aerogels prepared by freeze casting

Abstract: Graphene flake size has a profound effect on the mechanical performance of the assembled graphene aerogels, particularly their strength, modulus and fatigue resistance under compression.

Cited by 61 publications

References 40 publications

Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules

Simplified Approach for Preparing Graphene Oxide TEM Grids for Stained and Vitrified Biomolecules

Ice-templated hybrid graphene oxide—graphene nanoplatelet lamellar architectures: tuning mechanical and electrical properties

Fabrication of Three-Dimensional Copper@Graphene Phase Change Composite with High Structural Stability and Low Leakage Rate

Contact Info

Product

Resources

About