Sonochemical formation of single-crystalline gold nanobelts.
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Journal Article↗
Biomedical subjects
Jimin Du
Publications and source records attributed to Jimin Du.
Controlled synthesis of Ag/TiO2 core-shell nanowires with smooth and bristled surfaces via a one-step solution route.
Ag/TiO2 core-shell nanowires were synthesized via a one-step solution method without using a template. Interestingly, the shell morphologies can be controlled to be smooth or bristled by altering the reaction temperature. Moreover, the TiO2 shell thickness and bristle length can be tuned by changing the AgNO3 concentration. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected-area electron diffraction (SAED), energy-dispersive X-ray analysis (EDS), X-ray powder diffraction (XRD), and X-ray photoelectron spectroscopy (XPS) were used to characterize the resultant Ag/TiO2 core-shell nanowires. Moreover, the absorption peaks of our samples are significantly red-shifted compared with those of the uncoated pure silver nanowires, indicating that interaction between the core and shell occurred. On the basis of the experimental results, we proposed a template-induced Oswald ripening mechanism to explain the formation of the Ag/TiO2 core-shell nanowires.
Journal Article↗
Synthesis of noble metal/carbon nanotube composites in supercritical methanol.
A simple and efficient route has been employed to deposit noble metal nanoparticles (Pt, Ru, Pt-Ru, Rh, Ru-Sn) onto carbon nanotubes (CNTs) in supercritical methanol solution. In this method, the inorganic metallic salts acted as metal precursors, and methanol as solvent as well as reductant for the precursors. The as-prepared nanocomposites were structurally and morphologically characterized by X-ray diffraction spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy, and X-ray photoelectron spectroscopy analyses. It was demonstrated that the CNTs were decorated by crystalline metal nanoparticles with uniform sizes and a narrow particle size distribution. The size and loading content of the nanoparticles on CNTs could be tuned by manipulating reaction parameters. Furthermore, the formation mechanism of the composites was also discussed.
Chromatography, Supercritical Fluid↗
Microwave-assisted synthesis of pt nanocrystals and deposition on carbon nanotubes in ionic liquids.
In this work, a simple, fast and efficient route is presented for the metal (such as Pt, Rh, etc.) nanocrystal synthesis and deposition on carbon nanotubes (CNTs) in ionic liquids (ILs) via microwave heating. In this method, inorganic salts (such as H2PtCl6.4H2O, RhCl3.2H2O, etc.) dissolved in ILs, 1,1,3,3-tetramethylguanidinium trifluoroacetate or 1,1,3,3-tetramethylguanidinium lactate, were reduced to metal nanoparticles by glycol with the aid of microwave heating, and the produced metal nanoparticles could be decorated on CNTs in the presence of CNTs in ILs. The resulting nanomaterials were characterized by means of transmission electron microscopy and X-ray diffraction. It was demonstrated that the homogeneously dispersed Pt nanocrystals with the size of 2-3 nm were obtained using H2PtCl6.4H2O as precursor, and they deposited on CNTs with the similar size when CNTs was present in ILs. This technique also can be extended to fabricate other noble metal nanocrystals (including Rh, Au, etc.) and corresponding CNT composites.
Carbon↗
Synthesis of polyaniline nanofibrous networks with the aid of an amphiphilic ionic liquid.
In this work, polyaniline (PANI) nanofibrous networks were prepared using ionic liquid (IL), 1-hexadecyl-3-methylimidazolium chloride (C16MIMCl), as a template through oxidative polymerization of aniline with ammonium persulfate. The resulting PANI was characterized by means of scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-vis, and FTIR. It was indicated that the as-prepared PANI was in the emeraldine form and its morphology strongly depended on the molar ratio of aniline/C16MIMCI. A possible mechanism for the formation of PANI nanofibrous networks was that the ordered micro-domains of the IL acted as template to direct the growth of the nanostructures.
Aniline Compounds↗
Synthesis of single-crystal gold nanosheets of large size in ionic liquids.
Large-size single-crystal gold nanosheets have been successfully prepared by microwave heating of HAuCl(4) in ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate, without any additional template agent. Transmission electron microscopy (TEM), electron diffraction (ED), scanning electron microscopy (SEM), and X-ray powder diffraction (XRD) were used to characterize the resultant gold nanosheets. It was demonstrated that the ionic liquid could act as template agent for the formation of gold nanosheets. The present synthesis route is very simple and fast. It can be expected that the method can be extended to the fabrication of other metal nanosheets in ionic liquids.
Journal Article↗
Facile route to synthesize multiwalled carbon nanotube/zinc sulfide heterostructures: optical and electrical properties.
A simple method to decorate the multiwalled carbon nanotubes (MWCNTs) with ZnS nanospheres has been developed. The method involves ultrasonic pretreatment and heat treatments of MWCNTs, zinc chloride, and thiourea in ethanol. The heterostructures have been characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Comparative experiments show that both ultrasonic treatment and heat treatment are necessary for synthesizing the MWCNTs/ZnS heterostructures. Moreover, a photoluminescence spectrum shows that the MWCNTs/ZnS heterostructures feature a broad blue emission at about 430 nm, indicating that there exists significant ground-state interaction between ZnS nanospheres and MWCNTs. Meanwhile, the current-voltage characteristic of the MWCNTs/ZnS exhibits clear rectifying behavior, revealing charge transfer between MWCNTs and ZnS nanospheres.
Journal Article↗
Compressed-CO2-assisted patterning of polymers.
We report a facile route to pattern polymer surfaces with the aid of compressed CO(2), termed the compressed-CO(2)-assisted imprint method. In this method, compressed CO(2) serves as a plasticizer for polymers (such as poly(methyl methylate) and polystyrene), which leads to a tremendous reduction in the glass transition temperature and viscosity of the polymers. Nylon fabrics and anode aluminum oxide porous membranes are used as molds, respectively, to pattern the softened polymers at relatively low temperatures, resulting in patterns at the scale of micrometers and nanometers on the surface of polymer films. The patterned structures can be tuned by changing CO(2) pressure and temperature in the imprinting process. This method is simple and environmentally benign. It also can be operated at low temperatures, for instance, ambient temperature.
Journal Article↗
TX-100/water/1-butyl-3-methylimidazolium hexafluorophosphate microemulsions.
Both ionic liquids and water are typical green solvents. In this work, the phase behavior of the ternary system consisting of ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), TX-100, and water was determined at 25.0 degrees C. The water-in-bmimPF6, bicontinuous, and bmimPF6-in-water microregions of the microemulsions were identified by cyclic voltammetry method using potassium ferrocyanide K4Fe(CN)6 as the electroactive probe. Dynamic light scattering (DLS) and the UV-vis method were used to characterize the microemulsions. It was demonstrated that the hydrodynamic diameter (Dh) of the bmimPF6-in-water microemulsions is nearly independent of the water content but increases with increasing bmimPF6 content due to the swelling of the micelles by the ionic liquid. The UV-vis further confirmed the existence of water domains in the water-in-bmimPF6 microemulsions, and the salt potassium ferricyanide K3Fe(CN)6 could be dissolved in the water domains.
Journal Article↗
Replication of biological organizations through a supercritical fluid route.
A novel and simple method to replicate biological organizations (cotton and pollen grains) with high precision was proposed, in which the precursor dissolved in supercritical CO2 reacted with the surface active groups and adsorbed surface water on biological templates, followed by in situ SCF extraction of the byproducts and unreacted precursor, resulting in inorganic replicas faithfully copying both the macro- and microstructures of the biotemplates.
Carbon Dioxide↗
Tautomeric equilibrium of ethyl acetoacetate in compressed CO2 + ethanol and CO2 + methanol mixtures.
Tautomerism equilibrium of ethyl acetoacetate (EAA) in compressed CO2 + methanol and CO2 + ethanol mixtures was studied by UV-Vis spectroscopy at 308.15 K and different pressures. The volume expansion coefficient (alpha) of the solvents at different pressures was also determined. The relative permittivity (epsilon) of CO2 + methanol and CO2 + ethanol mixtures at different conditions was calculated using the Kc and Onsager solvent parameter. The equilibrium constant (Kc) of EAA in the binary mixtures increases considerably with increasing pressure or volume expansion coefficient. The relative permittivity or the polarity of the binary mixtures decreases sharply with increasing volume expansion coefficient in the range of 0 < alpha < 1.5. However, as the volume expansion coefficient exceeds 1.5, the relative permittivity decreases slowly. In other words, the dissolution of CO2 in the polar solvents can reduce the polarity of the solvents significantly in the low volume expansion coefficient range, and the polarity of the solution is not sensitive to the volume expansion coefficient as its value is large enough. The difference in polarity of the two solvents reduces with increasing pressure and becomes negligible after volume expansion coefficient exceeds about 2.5.
Acetoacetates↗
Organic reactions and nanoparticle preparation in CO(2)-induced water/P104/p-xylene microemulsions.
Nanometer-sized gold particles are synthesized by the reduction of HAuCl(4) with KBH(4) in the CO(2)-induced microemulsion of (EO)(27)(PO)(61)(EO)(27) (P104; EO=ethylene oxide, PO=propylene oxide)/p-xylene/CO(2)/H(2)O. The recovery of gold particles from the microemulsion can be easily accomplished by the venting of CO(2), while the surfactant remains in the organic phase. The effect of the molar ratio of the reductant to HAuCl(4), the concentration of the reactants, and the molar ratio of water to EO segments (W(0)) in the reverse micelles on the size of the gold particles is studied. The hydrolysis of benzoyl chloride (BzCl) and p-nitrophenyl chloroformate (NPhCl) has also been carried out in the microemulsion. The results show that the observed rate constants k(obs) of both substrates increase significantly with W(0), and that W(0) has a larger influence on the hydrolysis of BzCl. The different extents of the influence of W(0) on the two reactions can be ascribed to the different reaction mechanisms and the expected changes in nucleophilicity and polarity of water in the reverse micelles.
Journal Article↗