Synthesis of nanomaterials in microemulsions: formation mechanisms and growth control

López‐Quintela, M. Arturo

doi:10.1016/s1359-0294(03)00019-0

Cited by 420 publications

(257 citation statements)

References 77 publications

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“…Due to the gravity effects, the extended aging time as well as the large molecular weight of MoS 2 make the lipophilic group of the surfactant molecules gradually lost function that maintain the system stable, resulting in the particles irregularly aggregate and conglutinate one another [21].…”

Section: Resultsmentioning

confidence: 99%

Synthesis of chain-like MoS2 nanoparticles in W/O reverse microemulsion and application in photocatalysis

Liu

et al. 2012

Chin. Sci. Bull.

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Chain-like MoS 2 assemblies consisting of hexagonal MoS 2 nanoparticles (20-60 nm) have been successfully synthesized in a Triton X-100/cyclohexane/hexanol/water W/O reverse microemulsion in the presence of (NH 4 ) 2 MoS 4 as the molybdenum source and NH 2 OH·HCl as the reducing agent. The products were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM) and UV-vis diffuse reflectance absorption spectra. The influence of synthetic parameters such as acidity, water/oil ratio ( 0 ), aging time and annealing temperature on the formation of MoS 2 assemblies was investigated. TEM analysis showed that these synthetic factors played important roles in controlling the size of MoS 2 nanoparticles and the length of the chain-like MoS 2 assemblies. XRD analysis indicated that the well-crystallized MoS 2 nanoparticles could be obtained by annealing the precursors at 700C for 2 h under a flow of N 2 atmosphere. In addition, the as-prepared chain-like MoS 2 nanoparticles exhibited excellent photocatalytic H 2 activity in Ru ( The family of layered transition metal chalcogenides, such as MoS 2 , WS 2 , has aroused considerable interest during the past decade because of their unique properties and potential applications in hydrodesulfurization, Mg 2+ and Li + batteries, and solar photocells [1][2][3][4]. Increasing attention is now being focused on their potential applications as promising candidates for Pt, a co-catalyst and as well as a catalyst in photocatalytic H 2 production [5,6]. As it is well known, MoS 2 is an indirect, narrow band gap semiconductor (E g =1.0-1.2 eV, covering the range of solar spectrum energy) with high stability against photocorrosion in solution [7]. The band gap of MoS 2 depends on its crystallinity, size and shape due to the quantum confinement effect. Therefore, considerable effort has been made to the synthesis of MoS 2 nanomaterials with desired size and morphology. This material can be prepared under hydrothermal, solvothermal, sonolysis, inverse micelle, and -irradiation conditions [8][9][10][11][12]. Among the methods, the inverse micelle synthesis has been proven to be a convenient, effective and promising method to regulate the size and morphology of MoS 2 . In this approach, particles are grown inside inverse micelle cages dispersed in non-aqueous solvents. The particle size and morphology of MoS 2 crystals can be tailored through controlling the micelle size, which can be easily achieved by changing the emulsifier/water ratio. For example, Wilcoxon et al. [13,14] synthesized the nanosized MoS 2 crystals as small as 2.5 and 4 nm in EHAB/hexanol/octane and TDAB/hexanol/octane micelle solutions. Chikan et al. [15] obtained MoS 2 nanocrystals with the size of 3.5, 4.5 and 8 nm in DDAB/hexanol/ octane and TDAI/hexanol/octane ternary micelles, respectively. Osseo-Asare and co-workers [11] got MoS 2 nanoparticles ranging 10-80 nm in NP-5/cyclohexane/water microemulsion system. Xie and co-workers [16] fabricated necklace-shaped assembly of fullerene-like Mo...

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Section: Resultsmentioning

confidence: 99%

Synthesis of chain-like MoS2 nanoparticles in W/O reverse microemulsion and application in photocatalysis

Liu

et al. 2012

Chin. Sci. Bull.

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“…Reverse micelles stabilize reactive species that is insoluble in nonpolar solvents, and is also used as a size controlling micro-reactor for different aqueous chemical reactions 1,2 . Reverse micelles have been used as template for the synthesis of nanomaterials for a long time [3][4][5][6][7][8][9] . It has been found that the structure of the nanomaterials largely depends on the structure size and shape of the template micelles 10 .…”

Section: Introductionmentioning

confidence: 99%

Structure of Diglycerol Polyisostearate Nonionic Surfactant Micelles in Nonpolar Oil Hexadecane: A SAXS Study

Shrestha

Oyama

et al. 2010

J. Oleo Sci.

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Using a small-angle X-ray scattering technique, shape and size, and internal structure of diglycerol polyisostearate nonionic surfactant micelles in nonpolar oil n-hexadecane (HD) were investigated at 25 . Furthermore, the effect of added water on the structure of host reverse micelles was also investigated. The scattering data were evaluated by the generalized indirect Fourier transformation (GIFT) method and model fi ttings. It was found that diglycerol polyisostearate (abbreviated as (iso-C 18 ) n G 2 , where n = 2-4 represent the number of isostearate chain per surfactant molecule) spontaneously form reverse micelles in HD at 25 and their geometry (shape and size, and internal structure) could fl exibly be controlled by a small change in the lipophilic tail architecture of the surfactant, temperature, and water addition. Increasing number of isostearate chain per surfactant molecule decreases the micelles size favoring prolate-to-sphere type transition. This phenomenon could be best understood due to voluminous lipophilic part of the surfactant. Increasing temperature decreases the size of the reverse micelles due to enhanced interpenetration of the surfactant chain and the oil and also due to dominant hydrophobic character of the surfactant at higher temperatures. In the studies of effect of added water on the structure of micelles, it was found that the reverse micelles swell with water causing two dimensional micellar growths.

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“…Of recently, focus has shifted on NiO nanoparticles, due to their small size (<100 nm) and unique material and functional properties, such as a wide bandgap (∼3.88 eV), 2,3,5 high discharge capacity (∼638 mA h/g) 6 and specific capacitance (∼390 F/g), 7 high carrier density (∼7.35 × 10 18 cm -3 ), 8 and photon-to-current conversion efficiency (∼45%), 9 in addition to superb catalytic activity (42.3 gm -2 ) for CO oxidation, 10 which make them a highly desirable candidate for applications in electronics, electrochemical devices, photovoltaics, and catalysis, among others. Due to such attractive functional properties, a great deal of recent efforts have been devoted to develop application-relevant synthetic approaches, such as sol-gel embedded, 11 microemulsion precipitation, 12,13 and laser pulse deposition. 14,15 However, these approaches require complex multiple steps, often necessitating use of capping agents, and are time consuming.…”

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confidence: 99%

Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

et al. 2017

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Due to their unique chemical, thermal, electronic and photonic properties, low -dimensional transition metal oxides, especially NiO, have attracted great deal of attention for potential applications in a wide range of technologies, such as, sensors, electrochromic coatings and self-healing materials. However, their synthesis involves multi-step complex procedures that in addition to being expensive, further introduce impurities. Here we present a low cost facile approach to synthesize uniform size NiO nanoparticles (NPs) from hydrothermally grown Ni(OH)2. Detailed transmission electron microscopic analysis reveal the average size of NiO NPs to be around 29 nm. The dimension of NiO NP is also corroborated by the small area scanning tunneling microscope (STM) measurements. Further, we investigate electron transport characteristics of newly synthesized Ni(OH)2 and NiO nanoparticles on p-type Si substrate using scanning tunneling microscopy. The conductivity of Ni(OH)2 and NiO are determined to be 1.46x10-3 S/cm and 2.37x10-5 S/cm, respectively. The NiO NPs exhibit a lower voltage window (∼0.7 V) electron tunneling than the parent Ni(OH)2.

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Synthesis of nanomaterials in microemulsions: formation mechanisms and growth control

Cited by 420 publications

References 77 publications

Synthesis of chain-like MoS2 nanoparticles in W/O reverse microemulsion and application in photocatalysis

Synthesis of chain-like MoS2 nanoparticles in W/O reverse microemulsion and application in photocatalysis

Structure of Diglycerol Polyisostearate Nonionic Surfactant Micelles in Nonpolar Oil Hexadecane: A SAXS Study

Facile synthesis and electron transport properties of NiO nanostructures investigated by scanning tunneling microscopy

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