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ABSTRACT: Surface-enhanced Raman spectroscopy (SERS) benefits from the enhanced electromagnetic field of the localized surface plasmon resonance effect of metallic (especially coinage metals) nanoparticles or nanostructures. The detection sensitivity and reproducibility of SERS measurement appear to be the two critical issues in SERS. To solve the problem associated with traditional nanoparticle aggregates and SERS substrates, we propose in this work single particle SERS. We prepared uniform gold microspheres with controllable size and surface roughness using an etching-assisted seed-mediated method. Single particle dark-field spectroscopy and SERS measurements show that particles with a larger roughness give a stronger SERS signal, but still retain a good reproducibility. This study points to the promising future of the practical application of the single particle SERS technique for trace analysis.
Physical Chemistry Chemical Physics 02/2013; 15(12):4130-5. · 3.57 Impact Factor
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ABSTRACT: A dispersive scattering centers-based strategy was proposed to enhance the photocatalytic efficiency of photocatalysts in liquid-phase photochemical processes. Photocatalytic efficiencies of the photocatalyst, Degussa P25, in water splitting and photodegradation were markedly enhanced by using Ag nanosheets as dispersive scattering centers.
Nanoscale 01/2013; · 5.91 Impact Factor
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ABSTRACT: Metal-organic frameworks (MOFs) and related material classes are attracting considerable attention for their applications in gas storage/separation as well as catalysis. In contrast, research concerning potential uses in electronic devices (such as sensors) is in its infancy, which might be due to a great challenge in the fabrication of MOFs and semiconductor composites with well-designed structures. In this paper, we proposed a simple self-template strategy to fabricate metal oxide semiconductor@MOF core-shell heterostructures, and successfully obtained freestanding ZnO@ZIF-8 nanorods as well as vertically standing arrays (including nanorod arrays and nanotube arrays). In this synthetic process, ZnO nanorods not only act as the template but also provide Zn(2+) ions for the formation of ZIF-8. In addition, we have demonstrated that solvent composition and reaction temperature are two crucial factors for successfully fabricating well-defined ZnO@ZIF-8 heterostructures. As we expect, the as-prepared ZnO@ZIF-8 nanorod arrays display distinct photoelectrochemical response to hole scavengers with different molecule sizes (e.g., H(2)O(2) and ascorbic acid) owing to the limitation of the aperture of the ZIF-8 shell. Excitingly, such ZnO@ZIF-8 nanorod arrays were successfully applied to the detection of H(2)O(2) in the presence of serous buffer solution. Therefore, it is reasonable to believe that the semiconductor@MOFs heterostructure potentially has promising applications in many electronic devices including sensors.
Journal of the American Chemical Society 01/2013; · 9.91 Impact Factor
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ABSTRACT: A necklacelike SnO2/α-Fe2O3 hierarchical heterostructure was successfully fabricated by chemical vapor deposition method, using SnO2 nanowires with the preferential growth direction of [001] direction as template. Element mapping and transmission electron microscopy analysis proved that the hierarchical heterostructure was factually an assembly constructed with a SnO2/α-Fe2O3 nanocable and a series of pure α-Fe2O3 disks, and the interfacial orientation relationship was (100)SnO2//(110)Fe2O3 and [001]SnO2//[001]Fe2O3. Such a novel hierarchical heterostructure has been proved to present enhanced photocatalytic ability to degradation of methylene blue under visible light due to improvement of the hole−electron separation efficiency.
03/2011;
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ABSTRACT: The development of the instrumentation of a scanning electrochemical microscopy (SECM) is presented. The core of the SECM sensing system is constructed based on piezo-bimorph scanners, a mechanical micropositioner of multi-dimensional adjustment and ultramicroelectrodes. The control of the electrochemical cell and the SECM system is realized by a battery powered bipoteniostat and analog control circuits respectively with the control of a microcomputer work station. The demonstrations of SECM experiments are given on both a standard IDA sample and a silver electrode. Discussions on the resolution and quality of SECM image are made.
Chinese Journal of Chemistry 08/2010; 13(2):105 - 111. · 0.75 Impact Factor
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ABSTRACT: Fe electrodeposition on Au(111) and Au(100) in BMIBF(4) ionic liquid is found to form hitherto unreported shape-ordered nanoscale morphologies of pseudorods and pseudosquare rings, respectively, both composed of grains of 4-7 nm. The manner of growth of the square rings is a ring-on-ring structure with enlarging side length and slightly protruding four corners. The generality of the growth mechanism is verified by the formation of almost exactly the same shape-ordered Fe nanostructures on Pt, i.e., pseudorod structure on Pt(111) and pseudosquare rings Pt(100). These structures are explained within the framework of magnetostatic interactions of spontaneously magnetized grains under crystallographic constraint of the substrate surface, which result in an antiparallel arrangement in magnetization of the grains at pseudorods and magnetic flux closure at the pseudosquare rings. The closed magnetic flux further leads to magnetic field-enhanced growth at the four corners and the outer peripheries of the pseudosquare rings. The observed shape-ordering of the Fe thin film serves as a paradigm of magnetostatic coupling, in which the roles of ionic liquid as surfactant and magnetic media may not be underestimated. The present work adds a new dimension to electrodeposition in ionic liquid, by which new magnetic film structures may be expected.
Journal of the American Chemical Society 06/2010; 132(23):8152-7. · 9.91 Impact Factor
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ABSTRACT: In this article, we demonstrate successful application of a top-down strategy based on a selective wet-chemical etching technique in fabrication of nanostructures with a special morphology. Pagoda-like and hexagonal pyramidal ZnO nanostructures with the polar (000 (1) over bar) and {10 (1) over bar1} planes as exposed surfaces have been synthesized by refluxing ZnO columns mainly bounded with {10 (1) over bar0} nonpolar faces in the mixed solvent of oleic acid (OA) and 1-octylamine. Adequate evidence demonstrates that OA in the mixed solvent acts as the etchant in the process of morphology evolution, and the appropriate proportion of OA, reaction time, and reaction temperature are crucial for controlling the etching degree of ZnO. Through the selective wet-chemical etching, it has been confirmed that the dumbbell-like ZnO is of twinning morphologies growing along contrary direction on both sides of the (0001) twinning plane. Therefore, our present work provides a simple way to estimate the complicated twinning phenomena. National Natural Science Foundation of China [20725310, 20721001, 20673085, 20801045]; Key Scientific Project of Fujian Province of China [2009HZ0002-1]; National Basic Research Program of China [2007CB815303, 2009CB939804]
The Journal of Physical Chemistry C 06/2010; · 4.80 Impact Factor
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ABSTRACT: Porous hollow nanostructures have attracted intensive interest owing to their unique structure and promising applications in various fields. A facile hydrothermal synthesis has been developed to prepare porous hollow nanostructures of silicate materials through a sacrificial-templating process. The key factors, such as the concentration of the free metal cation and the alkalinity of the solution, are discussed. Porous hollow nanostructures of magnesium silicate, nickel silicate, and iron silicate have been successfully prepared by using SiO(2) spheres as the template, as well as a silicon source. Several yolk-shell structures have also been fabricated by a similar process that uses silica-coated composite particles as a template. As-prepared mesoporous magnesium silicate hollow spheres showed an excellent ability to remove Pb(2+) ions in water treatment owing to their large specific surface and unique structures.
Chemistry - An Asian Journal 04/2010; 5(6):1439 - 1444. · 4.50 Impact Factor
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ABSTRACT: Ag(2)O particles with different polyhedral shapes including octahedron, truncated octahedron, and cube were successfully synthesized by a simple wet-chemical method using silver nitrate, ammonia, and sodium hydroxide as raw materials at room temperature. Simply by tuning the concentration of starting materials, the shape of Ag(2)O particles evolved from octahedron to cube, and the size gradually decreased from 1-2 microm to 400-700 nm. As examples for promising applications, the antibacterial activities of the as-prepared Ag(2)O polyhedral particles were preliminarily studied. It has been found the antibacterial activity of Ag(2)O particles against E. coli depends on the shape of Ag(2)O particles, demonstrating that the surface structure of Ag(2)O particles affects the antibacterial activity.
Langmuir 02/2010; 26(4):2774-8. · 4.19 Impact Factor
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ABSTRACT: Higher-ordered architectures self-assembly of nanomaterials have recently attracted increasing attention. In this work, we report a spontaneous and efficient route to simultaneous synthesis and self-assembly of 3D layered β-FeOOH nanorods depending on a pH-induced strategy, in which the continuous change of pH is achieved by hydrolysis of FeCl 3 3 6H 2 O in the presence of urea under hydrothermal conditions. The electron microscopy observations reveal that the square-prismic β-FeOOH nanorods are self-assembled in a side-by-side fashion to form highly oriented 2D nanorod arrays, and the 2D nanorod arrays are further stacked in a face-to-face fashion to form the final 3D layered architectures. On the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the 3D layered β-FeOOH nanorods architecture is presented, involving the fast growth and synchronous self-assembly of the nanorods toward 1D, 2D, and 3D spontaneously. The experimental evidence further demonstrates that the urea-decomposition-dependent pH continuously changing in the solution, spontaneously altering the driving force competition between the electrostatic repulsive force and the attractive van der Waals force among the nanorods building blocks, is the essential factor to influence the self-assembly of the β-FeOOH nanorods from 1D to 3D.
Langmuir 01/2010; 26:2745-2750. · 4.19 Impact Factor
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ABSTRACT: Here we proposed a synthetic method of high-purity Ag nanoplates by the reduction of aqueous Ag+ ions at the aqueous-organic interface with the reductant ferrocene. We demonstrated that the as-prepared Ag nanoplates can be widely tunable from 600 nm to 7 mu m in size and from 10 to 35 nm in thickness, simply by adjusting the component of organic phase To our knowledge, there are few methods to tailor the size and the thickness of metal nanoplates in such a large range although many efforts have been made aiming to realize it. Our proposed synthetic strategy is rapid, template-free, seed-less, and high-yield, and could be applied to synthesize analogous two-dimensional nanostructures of other noble metals, such as Pt, Au, and Pd. (C) 2010 Elsevier Inc All rights reserved. National Natural Science Foundation of China [20725310, 20721001, 20801045]; National Basic Research Program of China [2007CB815303, 2009CB939804]; Key Scientific Project of Fujian Province of China [2009HZ0002-1]
Journal of Solid State Chemistry 01/2010; · 2.16 Impact Factor
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ABSTRACT: Higher-ordered architectures self-assembly of nanomaterials have recently attracted increasing attention. In this work, we report a spontaneous and efficient route to simultaneous synthesis and self-assembly of 3D layered beta-FeOOH nanorods depending on a pH-induced strategy, in which the continuous change of pH is achieved by hydrolysis of FeCl(3).6H(2)O in the presence of urea under hydrothermal conditions. The electron microscopy observations reveal that the square-prismic beta-FeOOH nanorods are self-assembled in a side-by-side fashion to form highly oriented 2D nanorod arrays, and the 2D nanorod arrays are further stacked in a face-to-face fashion to form the final 3D layered architectures. On the basis of time-dependent experiments, a multistage reaction mechanism for the formation of the 3D layered beta-FeOOH nanorods architecture is presented, involving the fast growth and synchronous self-assembly of the nanorods toward 1D, 2D, and 3D spontaneously. The experimental evidence further demonstrates that the urea-decomposition-dependent pH continuously changing in the solution, spontaneously altering the driving force competition between the electrostatic repulsive force and the attractive van der Waals force among the nanorods building blocks, is the essential factor to influence the self-assembly of the beta-FeOOH nanorods from 1D to 3D.
Langmuir 12/2009; 26(4):2745-50. · 4.19 Impact Factor
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ABSTRACT: Neutral inorganic molecules are generally weak in surface adsorption and intermolecular interactions. Self-assembly of such types of molecule would provide valuable information about various interactions. At electrochemical interfaces, the relative strength of these interactions may be modified through control of electrode potential and electrolyte, which may lead to the discovery of new structures and new phenomena. However, studies of this nature are as yet lacking. In this work, we consider the covalent-bound semimetal compound molecules, XCl(3) (X = Sb, Bi), as model systems of neutral inorganic molecules to investigate their self-assembly at electrochemical interfaces under a high ionic atmosphere. To fulfill such investigations, in situ STM and cyclic voltammetry are employed, and comparative experiments are performed on Au(111) in ionic liquids as well as aqueous solutions with high ionic strength. In the room temperature ionic liquid of 1-butyl-3-methylimidazolium tetrafluoroborate (BMIBF(4)), potential-dependent partial charge transfer between the Au surface and XCl(3) molecules creates a molecule-surface interaction and provides the driving force for adsorption of the molecules. Supramolecular aggregations of adsorbed XCl(3) are promoted through chlorine-based short-range intermolecular correlation under crystallographic constraint, while repulsive Coulombic interactions created between the partially charged aggregations facilitate their long-range ordering. For SbCl(3) molecules, hexagonally arranged 6- or 7-member clusters are formed at 0.08 to -0.2 V (vs Pt), which assemble into a secondary ( radical31 x radical31)R8.9 degrees structure. For BiCl(3) molecules, both the 6-membered hexagonal and 3-membered trigonal clusters are formed in the narrow potential range -0.3 to -0.35 V, and are also arranged into an ordered secondary structure. Comparative studies were performed with SbCl(3) in concentrated aqueous solutions containing 2 M HCl to simulate the strong ionic strength of the ionic liquid. Almost identical 6-/7-member clusters and long-range ( radical31 x radical31)R8.9 degrees structure are observed at -0.1 V, demonstrating the crucial role of strong ionic strength in such supramolecular aggregations. However, such supramolecular structures are modified and eventually destroyed as ionic strength is further increased by addition of NaClO(4) up to 6 M. The destructive changes of the supramolecular structures are attributed to the alteration of ion distribution in the double layer from cation-rich to anion-rich at increasing NaClO(4) concentration. This modifies and eventually breaks the balance of intermolecular and molecule-electrolyte interactions. Finally, the dynamic behavior of the SbCl(3) assembly is investigated down to molecular level. It has been demonstrated that the initial stage of assembly follows a two-dimensional nucleation and growth mechanism and has a potential-dependent rate that is closely related to the surface mobility of the SbCl(3) clusters. There is a probability that clusters can escape from an existing assembly domain or insert into a vacancy in such a domain while they can also relax with central or ring members in a dynamic fashion. These phenomena indirectly reflect the dynamic properties of cations from electrolytes at the interface. The rich information contained in the self-assembly behavior of SbCl(3) and BiCl(3) demonstrates that neutral inorganic molecules can be employed for fundamental studies of a variety of interesting issues, especially the interplay of various interfacial interactions.
Journal of the American Chemical Society 09/2009; 131(41):14728-37. · 9.91 Impact Factor
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Hai-Ming Zhang,
Zu-Kui Pei, Zhao-Xiong Xie,
谢兆雄,
La-Sheng Long,
龙腊生,
Bing-Wei Mao,
毛秉伟,
Xin Xu,
徐昕,
Lan-Sun Zheng,
郑兰荪
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ABSTRACT: A kind of robust molecular template formed between melamine (M) and cyanuric acid (CA) molecules on highly oriented pyrolytic graphite (HOPG) surfaces has been prepared by putting a droplet of hot aqueous solutions containing equal mol of M and CA molecules on preheated substrate. The CA.M SAMs exhibit features of hexagonal open networks which makes them an ideal molecular template for further processing of functional guest entities. In addition to the preparation of CA.M SAMs, SAMs of M and CA molecules alone were also studied on HOPG surfaces. Chiral structures were found in the SAMs of M molecules. National Natural Science Foundation of China [20725310, 20533030, 20525311, 20673085, 20671078]; National Basic Research Program of China [2007CB815303, 2007CB815206]; Key Scientific Project of Fujian Province of China [2005HZ01-3]; NCET from the Ministry of Education of China
07/2009;
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ABSTRACT: A novel direct readout colorimetric optical glucose sensor strip was constructed based on a three-layer film, including a green-emitted CdTe/CdS quantum dots (QDs) layer as a stable color background, a red-fluorescent platinum-porphyrin oxygen-sensing layer and a glucose oxidase layer. The sensor achieved high resolution (up to 0.2 mmol L(-1)) glucose determination with a detection range from 0 to 3.0 mmol L(-1). A "glucose ruler" which acts as a glucose standard colorimetric card was obtained. Glucose concentration could easily be directly readout using the "glucose ruler", which made the glucose determination rapid, convenient and easy. The effects of pH, salinity and temperature were systematically investigated. The prepared sensor was finally applied for glucose sample analysis, compared with the "glucose ruler", accurate results could be directly readout.
Biosensors & bioelectronics 06/2009; 24(12):3702-5. · 5.43 Impact Factor
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ABSTRACT: Nearly monodisperse single-crystalline palladium (Pd) nanocubes and nanodendrites have been successfully prepared in aqueous solution at room temperature, for the first time, mainly by utilizing the equilibrium between the dissolution and precipitation of the Pd-cetyltrimethylammonium bromide (Pd-CTAB) complexes. The morphology of the obtained Pd nanocrystals can be tuned by the addition of foreign halide ions (Cl− and Br−). The corresponding selected area electron diffraction (SAED) and X-ray diffraction (XRD) patterns confirmed that the synthesis of nanocubes and nanodendrites are single-crystalline pure Pd structures with fcc crystal lattice. A preliminary formation mechanism based on the dissolution and precipitation of the Pd-CTAB complexes and competitive adsorption between different ions on the nanoparticle surface has been proposed.
05/2009;
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ABSTRACT: A colorimetric electrochemiluminescence (ECL) sensor was fabricated for the first time, based on a dual-color system including a strong red Ru(bpy)(3)(2+) ECL and a green reference light from a light emitting diode. Traditional ECL intensity information can be easily transformed into a color variation with this sensor, and the color variation can be directly monitored using the naked eye or a commercial CCD camera. The sensor has been successfully used to determine the concentration of tripropylamine, proline (enhancing system), and dopamine (quenching system). The results indicated that the color variation obtained corresponded to the concentration of target analytes. This sensor has potential application in rapid and semiquantitative ECL analysis.
Analytical Chemistry 01/2009; 81(2):830-3. · 5.86 Impact Factor
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Xi-Guang Han,
Hui-Zhong He,
Qin Kuang,
匡勤,
Xi Zhou,
Xian-Hua Zhang,
Tao Xu, Zhao-Xiong Xie,
谢兆雄,
Lan-Sun Zheng,
郑兰荪
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ABSTRACT: In this paper, we successfully synthesized three kinds of typical ZnO micro/nanocrystallites including flakes, columns, and pyramids by means of different facile wet chemical routes. The growth environment plays a crucial role in the morphologies of these ZnO micro/nanocrystallites. At the same time, we find that physical/chemical properties of these ZnO samples are dependent on their exposed surface, and the order of gas sensing and photocatalytic efficiency of the ZnO crystal planes is (0001) > {10 (1) over bar0} > {10 (1) over bar1} and (000 (1) over bar). On the basis of structural analyses of various exposed surfaces and related X-ray photoelectron spectroscopy, we deeply discussed the effect of definite surface structures on their gas sensing and photocatalytic properties. National Natural Science Foundation of China [20725310, 20721001, 20673085, 20801045]; National Basic Research Program of China [2007CB815303, 2009CB939804]
12/2008;
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ABSTRACT: a b s t r a c t In this paper, we report a simple two-step approach to prepare porous octahedron-and rod-shaped ZnO architectures. The morphology of porous ZnO particles can be conveniently tuned by controlling morphologies of the ZnC 2 O 4 Á 2H 2 O precursor. SEM and TEM characterization results indicate that these porous ZnO architectures are built up by numerous ZnO primary nanoparticles with random attachment. Based on thermogravimetry analysis, we believe that the release of water vapor, CO and CO 2 leads to the formation of high-density pores in shape-controlled particles during the calcination process. Further experimental results indicate that as-prepared porous ZnO particles exhibit good photocatalytic activity due to large surface area.
11/2008;
