Hollow graphene oxide spheres self-assembled by W/O emulsion

Guo, Peng; Song, Huaihe; Chen, Xiaohong

doi:10.1039/b927302f

Cited by 172 publications

(137 citation statements)

References 61 publications

(72 reference statements)

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“…In 2010, the further progression of graphene-based host structures (i.e., hollow GO spheres, [ 43 ] RGO, [ 37,39,[44][45][46][47][48][49][50] unzipped CNT, [ 51 ] bottom-up-synthesized graphene, [ 52 ] CVD-synthesized graphene [ 40 ] and N-doped graphene [ 40 ] ) only enabled limited progresses (Table 1 ). However, some major advances in understanding the Li-ion storage mechanism in different kinds of graphene were reported.…”

Section: Continuedmentioning

confidence: 99%

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

et al. 2016

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that its extraordinary properties would enable revolutionary new technologies, which gave birth to the "graphene era". [ 3,4 ] Relying on this scenario, in 2013, the European Union launched the ¤1 billion "Graphene Flagship" project aimed to investigate the properties of this new form of carbon for various applications (e.g., electronics, sensors and energy storage devices), with the ambitious goal of guiding graphene from laboratories to commercial applications within a decade. [ 5,6 ] In the same period, the Chinese Government set up a similar investment to mass-produce graphene as thin fi lms (e.g., for touchscreen electrodes) and platelets (e.g., for use in batteries). [ 6 ] In the following years, hundreds of patents, mainly focused on manufacturing and application in energy storage, were fi led and the worldwide production of graphene and graphene-containing materials rapidly increased. Although a few Chinese industries claimed to already use graphene-containing materials for smartphone production, no revolutionary practical application relying on graphene has been yet developed. [ 6 ] Specifi cally with respect to the battery fi eld, a close analysis of the scientifi c literature reveals a struggle to meet the ambitious initial targets. A potential loss of focus from the fi nal application caused by hype and ease of publication on such a novel matter, together with the delivery of very misleading information [ 7,8 ] and erroneous statements [ 7 ] concerning the use of graphene in batteries are emerging as possible reasons of the ineffective graphene-era outburst. In this progress report, we do not focus on production and classifi cation of graphene and graphene-containing materials, which were already well reported in the past years. [ 3,[9][10][11] In contrast, due to the lack of an exhaustive analysis of the progression of the use of such materials in lithium-ion battery (LIB) anodes, we report here a critical evaluation of the most prominent research papers published from 2008 until the end of 2015. As shown in Figure 1 , three different stages of the graphene research in LIB anodes can be distinguished: a fi rst stationary phase between 2008 and 2010 where the lithium-ion storage properties of different graphene and graphene-containing materials were preliminarily explored, a second exponential stage, spanning from 2010 to 2014, where graphene and graphene-containing anode materials were broadly developed and investigated, and fi nally, a third phase, (i.e., starting from 2015), where the research seems to have approached a plateau. After Used as a bare active material or component in hybrids, graphene has been the subject of numerous studies in recent years. Indeed, from the fi rst report that appeared in late July 2008, almost 1600 papers were published as of the end 2015 that investigated the properties of graphene as an anode material for lithium-ion batteries. Although an impressive amount of data has been collected, a real advance in the fi eld still seems to be missing. In this framework, atten...

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Section: Continuedmentioning

confidence: 99%

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

et al. 2016

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“…If the GO sheets are large, they cannot easily remain at the oil-water interface to stabilize the oil dispersion in the aqueous phase like smaller ones, resulting in small particles adhering randomly to the wide GO sheets. Guo et al [26] reported that hollow graphene oxide spheres were generated from self-assembled graphene oxide nanosheets in a water-in-oil emulsion system without surfactants. Owing to the special properties of GO, GO was used in DI water to stabilize PMMA microparticles to form core-shellstructured PMMA/GO composite particles via a self-assembled process without the addition of surfactants in this study.…”

Section: Introductionmentioning

confidence: 99%

Facile fabrication of self-assembled PMMA/graphene oxide composite particles and their electroresponsive properties

Zhang

Choi

2012

Colloid Polym Sci

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Core-shell-structured poly(methyl methacrylate) (PMMA)/graphene oxide (GO) composite particles were prepared using a facile process, in which GO was adsorbed spontaneously onto a microspherical PMMA surface when hydrophobic microspheres were dispersed in deionized (DI) water stabilized by amphiphilic GO under ultrasonication. The fabricated composite was characterized by SEM, TEM, FT-IR, and thermogravimetric analysis. Results showed that the particle surface could be wrapped with GO without the need for surfactants. In addition, electrorheological behavior of the chain-forming process of the PMMA/GO composite particles was observed by optical microscopy under an applied electric field. Both shear stress and shear viscosity related to the strength of the applied electric field were measured using a rotational rheometer. The proposed Cho-Choi-Jhon model was used to describe their ER performances for the entire shear rate region. Moreover, the response of the shear stress to an imposed square voltage at a fixed shear rate was also examined.

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“…GO therefore adsorbs on the surface of hexane droplets and other nonpolar solvents acting as an emulsion stabilizer and preventing their breakdown and coalescence from water suspensions. 7,26 This effect also remains when GO is partially substituted by CNTs with a droplet mean size of 212 microns (see the ESI †). During the hydrothermal process the graphene oxide sheets are reduced and assembled around the hexane droplets which act as soft templates for macroporous structures.…”

Section: Scaffold Characterizationmentioning

confidence: 84%

“…These results confirm that the supercritical water produced under the hydrothermal condition plays the role of a reducing agent and offers an effective reduction approach for graphene oxide. 26 By contrast, oxidized carbon nanotubes show no significant changes after HT. GO and GR were characterized by FTIR (ESI †).…”

Section: Scaffold Characterizationmentioning

confidence: 94%

“…27 These results suggest the partial reduction of GO in the hydrothermal reduction and the existence of p-p stacking between graphene sheets after hydrothermal treatment. 26 The XRD pattern of oxidized carbon nanotubes (CNTox) shows two intense peaks at scattering angles of 26.11 and 44.251 which correspond to (0 0 2) and (1 0 1) planes of hexagonal graphite respectively. Some other low intensity peaks corresponding to the remaining catalyst iron oxides can also be observed.…”

Section: Scaffold Characterizationmentioning

confidence: 99%

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High porosity scaffold composites of graphene and carbon nanotubes as microwave absorbing materials

2016

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The design of microwave absorbing materials requires low reflection and high absorption of radiation simultaneously. Low reflection of electromagnetic waves can be achieved inducing porous faces which minimize the impedance mismatch. High absorption can be obtained by increasing the conductivity of the material. We report the preparation of highly porous scaffolds from a combination of graphene and carbon nanotubes. The bimodal porous structure was controlled making use of the surface properties of graphene oxide that are able to stabilize hexane droplets in aqueous dispersions of graphene oxide and carbon nanotubes. After hydrothermal and two step freeze-drying processes, macro-(220 microns) and mesoporous (10 microns) structures, due to hexane droplets and freeze drying, respectively, were obtained. DC conductivities of 8.2, 14.7, 33.2, and 60.7 S m 1 were obtained for graphene scaffolds containing 0, 10, 20 and 40% of carbon nanotubes respectively. An electromagnetic characterization was performed on scaffolds infiltrated with epoxy resin; using appropriate models, the electromagnetic properties of the conducting phase have been obtained. Scaffolds with a thickness of 9 mm were able to absorb up to 80% of the incident radiation keeping the reflection as low as 20%.

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Hollow graphene oxide spheres self-assembled by W/O emulsion

Cited by 172 publications

References 61 publications

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

Critical Insight into the Relentless Progression Toward Graphene and Graphene‐Containing Materials for Lithium‐Ion Battery Anodes

Facile fabrication of self-assembled PMMA/graphene oxide composite particles and their electroresponsive properties

High porosity scaffold composites of graphene and carbon nanotubes as microwave absorbing materials

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