Janus graphene oxide nanosheets prepared via Pickering emulsion template

Wu, Hao; Yi, Wenyuan; Chen, Zhe; Wang, Haitao; Du, Qiangguo

doi:10.1016/j.carbon.2015.05.083

Cited by 122 publications

(93 citation statements)

References 65 publications

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“…Initially, GO was synthesized from chemical oxidation of graphite (15). Single-surface hydrophobization was then carried out (16,17). The nanofluid was made stable to avoid agglomeration of the nanosheets.…”

Section: Methodsmentioning

confidence: 99%

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Luo

Wang

Zhu

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

211

143

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The current simple nanofluid flooding method for tertiary or enhanced oil recovery is inefficient, especially when used with low nanoparticle concentration. We have designed and produced a nanofluid of graphene-based amphiphilic nanosheets that is very effective at low concentration. Our nanosheets spontaneously approached the oil-water interface and reduced the interfacial tension in a saline environment (4 wt % NaCl and 1 wt % CaCl 2 ), regardless of the solid surface wettability. A climbing film appeared and grew at moderate hydrodynamic condition to encapsulate the oil phase. With strong hydrodynamic power input, a solid-like interfacial film formed and was able to return to its original form even after being seriously disturbed. The film rapidly separated oil and water phases for slug-like oil displacement. The unique behavior of our nanosheet nanofluid tripled the best performance of conventional nanofluid flooding methods under similar conditions. nanofluid flooding | amphiphilic Janus nanosheets | enhanced oil recovery | climbing film | interfacial film F inding economically viable and environmentally friendly methods to extract the huge amount of residual oil after primary and secondary recovery remains challenging for the oil and gas industry and is also of significant importance in efforts to satisfy the world's increasing energy demand. Nanofluid flooding as an alternative tertiary oil recovery method has been recently reported (1-5). Obviously, simple nanofluid flooding (containing only nanoparticles) at low concentration (0.01 wt % or less) shows the greatest potential from the environmental and economic perspective. Several corresponding oil displacement mechanisms have also been introduced, including reduction of oil-water interfacial tension (6, 7), alteration of rock surface wettability (8-10), and generation of structural disjoining pressure (11-13). However, the oil recovery factor is below 5% with 0.01% nanoparticle loading in core flooding tests in a saline environment (2 wt % or higher NaCl content). Here we show that an oil recovery factor of 15.2% is achieved by using a simple nanofluid of graphene-based Janus amphiphilic nanosheets. To our knowledge, this is the first report of applying nanofluid of amphiphilic Janus two-dimensional materials in tertiary or enhanced oil recovery. We found that in a saline environment, the nanosheets spontaneously approach the oil-water interface, reducing the interfacial tension. A climbing film emerges and encapsulates the oil phase and may carry it forward. Furthermore, we found that a solid-like film forms with strong hydrodynamic power. The film rapidly separates oil and water for slug-like oil displacement. Even though there are ways to achieve 20% enhanced recovery by complicated alkali/surfactant/polymer flooding (14) or by surfactants with added nanoparticles (5), the necessary concentrations of the chemicals and nanoparticles are much higher than 0.01 wt %. Our results provide a nanofluid flooding method for tertiary oil recovery that is compar...

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Section: Methodsmentioning

confidence: 99%

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Luo

Wang

Zhu

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

211

143

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“…The exposed fresh side of the graphene was further functionalized by phenylation reaction. Graphene-based Janus nanosheets were also prepared using a Pickering emulsion [25]. A graphene oxide (GO) dispersion was mixed with hydrochloric acid and wax, and this mixture was ultrasonicated to prepare a Pickering emulsion.…”

Section: Introductionmentioning

confidence: 99%

Janus Nanosheets Derived from K₄Nb₆O₁₇·3H₂O via Regioselective Interlayer Surface Modification

Suzuki¹,

Sudo²,

Hirano³

et al. 2019

Functional Materials

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Inorganic Janus nanosheets were successfully prepared using the difference in reactivity between interlayers I and II of layered hexaniobate K 4 Nb6O 17 ·3H 2 O. Janus nanosheets exhibit the highest anisotropy among Janus compounds due to their morphology. It is therefore important to prepare Janus nanosheets with stable shapes in various solvents, robust chemical bonds between nanosheets and fuctional groups and high versatility due to surface functional groups. K 4 Nb 6 O 17 ·3H 2 O, which possesses two types of interlayers and two types of organophosphonic acids that react with metal oxides to form robust covalent bonds, was employed to prepare Janus nanosheets for this study. Interlayer I was modified by octadecylphosphonic acid, followed by modification by carboxypropylphosphonic acid mainly at interlayer II. Preparation of Janus nanosheets with two organophosphonate moieties was confirmed by 31 P MAS NMR. After these regioselective and sequential modifications, the products were exfoliated into single-layered nanosheets in THF. Two types of derivatives with different repeating distances were recovered from a dispersion containing nanosheets exfoliated by different processes, centrifugation, and solvent evaporation. AFM analysis of the exfoliated nanosheets revealed that the products were Janus compounds. There are high expectations for application of these types of Janus nanosheets in various fields and for design of various Janus nanosheets using this preparation method.There are various methods of preparing Janus nanoparticles. Regioselective surface modification of nanoparticles can produce Janus nanoparticles [11]. By forming nanoparticles with two raw materials, Janus nanoparticles with different compositions can be prepared [2]. Self-assembly and subsequent cross-linking of polymer chains can also produce Janus nanoparticles [12]. Janus rods can be prepared by forming silica using TEOS by the sol-gel method on Fe 3 O 4 regioselectively [13]. Janus cylinders can be prepared by masking one side of a cylinder and conducting subsequent modification of the other side [14].Janus nanosheets exhibit the highest anisotropy among Janus compounds due to their unique morphology. They are also useful as emulsifiers, because Janus nanosheets cannot rotate at the interfaces of micelles [15]. Most Janus nanosheets reported so far have consisted of polymers. Stupp et al. reported the preparation of Janus nanosheets by polymerization of oligomers with polymerizable groups [16]. Polymerization of oligomers led to the formation of sheet morphology, because the polymerizable groups were located at the center of an oligomer. Walther et al. used triblock copolymers, polystyrene-block-polybutadiene-block-poly(tert-butyl methacrylate), for preparing Janus nanosheets [17]. Janus nanosheets were prepared by cross-linking polybutadiene domains of the triblock copolymers, and the resulting Janus nanosheets had two types of surfaces, polystyrene, and poly(tertbutyl methacrylate) moieties. These methods are based on selective polym...

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“…One key difference of this reported method is that it uses a destructive strategy. Other methods use the conventional additive strategy, which functionalizes particles with the surface coating only after the particles are embedded in wax . These particles sometimes require surfactants, which may limit their ability to uptake the functional coatings.…”

Section: Resultsmentioning

confidence: 99%

“…The extent of particle embedment in the wax could be tuned using surfactants that increase the hydrophobicity of the particle, allowing it to be embedded more deeply . Since then, many other methods have employed paraffin wax as an emulsification template to functionalize various particles and surfaces . Due to the vast property combinations available on Janus particles, they may find applications as probes and sensors, micromotors and nanomotors, in electronic paper, in cargo encapsulation and delivery, etc …”

Section: Introductionmentioning

confidence: 99%

Preparation of Janus Titanium Dioxide Particles via Ultraviolet Irradiation of Pickering Emulsions

Tan

Wong

Chen

2020

Adv Materials Inter

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Pickering emulsions are stabilized by solid particles assembled at an immiscible liquid–liquid interface. In this work, the use of such emulsions to prepare semiconductor Janus particles through UV‐irradiation is explored. Titanium dioxide particles that are prefunctionalized with an alkylsilane or a fluoroalkylsilane are employed to obtain wax‐in‐water emulsion droplets, which consist of the particles partially embedded in the wax core. Different emulsion formation mechanisms are discussed. The emulsified wax droplets are then subjected to ultraviolet irradiation, which photocatalytically degrades the silanes on the exposed portion of the particle surfaces, leading to Janus particles containing partial silane coatings. The particles are finally recovered through dissolution of wax. The Janus particles, which have contrasting wettabilities over their surface, are characterized based on self‐assembly behavior and bulk wetting performance in a compact film, as compared with nonfunctionalized and fully‐functionalized homogeneous particles. Three different types of Janus particles are created and their characters are explained using the concept of the Janus balance. The method has the potential to produce large scale yields in a relatively short time, and can be potentially applied to other semiconductor particles for the generation of Janus particles.

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Janus graphene oxide nanosheets prepared via Pickering emulsion template

Cited by 122 publications

References 65 publications

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Janus Nanosheets Derived from K₄Nb₆O₁₇·3H₂O via Regioselective Interlayer Surface Modification

Preparation of Janus Titanium Dioxide Particles via Ultraviolet Irradiation of Pickering Emulsions

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Janus graphene oxide nanosheets prepared via Pickering emulsion template

Cited by 122 publications

References 65 publications

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Nanofluid of graphene-based amphiphilic Janus nanosheets for tertiary or enhanced oil recovery: High performance at low concentration

Janus Nanosheets Derived from K4Nb6O17·3H2O via Regioselective Interlayer Surface Modification

Preparation of Janus Titanium Dioxide Particles via Ultraviolet Irradiation of Pickering Emulsions

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Janus Nanosheets Derived from K₄Nb₆O₁₇·3H₂O via Regioselective Interlayer Surface Modification