Xueliang Qiao

Huazhong University of Science and Technology, Wu-han-shih, Hubei, China

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Publications (58)118.53 Total impact

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    ABSTRACT: Ag/ZnO/graphene (Ag/ZnO/G) nanocomposites were successfully synthesized by a facile low-temperature microwave-assisted solution method. The morphology and phase structure of the prepared samples were characterized by field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The photocatalytic performance of the obtained products were evaluated by analyzing the degradation of methyl orange (MO) solution under UV irradiation. The Ag/ZnO/graphene nanocomposites showed higher photocatalytic efficiency than ZnO or Ag/ZnO. Photocatalytic activity of Ag/ZnO/graphene nanocomposites with different graphene content was studied. Firstly the photocatalytic efficiency of the Ag/ZnO/graphene nanocomposites increased with the increase of graphene oxide (GO) content from 0 to 1%, then the photocatalytic efficiency decreased while the percent of GO addition reached 2%. The photostability testing of the Ag/ZnO/graphene nanocomposites with 1% GO content showed that the catalyst has excellent photocatalytic activity and photostability for the degradation of MO. It is believed that this facile, rapid microwave-assisted strategy is scalable and can be applied to synthesize other metal/semiconductor oxide/graphene nanocomposites for different applications in different fields.
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    ABSTRACT: Silver nanorods with different polydispersity were synthesized in the cetyltrimethylammonium bromide (CTAB) rod-shaped micelles by inducing the orientation growth of silver seeds and adjusting the volumes of CTAB. The reaction for the formation of silver nanorods had basically finished in 10 min. A suitable volume of CTAB (i.e., 15.0 mL of 0.1 M CTAB) is beneficial to obtain high-quality silver nanorods in the given reaction system. That is, the volume of added CTAB is a key factor to determine the polydispersity of the formed nanorods. The aging time plays a critical role in the morphology evolution of silver nanorods due to the oxidation of silver nanorods with Br-, O-2 and the Ostwald ripening of the nanoparticles. As a result, the characteristic spectral changes occurred due to the morphology evolution of silver nanorods. The ablation in the top ends of the longer nanorods is often accompanied by the growth of some shorter nanorods and nanospheres. The size distribution of silver nanorods might be more uniform in the early aging stage. All the nanorods in the colloidal solution should turn into the near-spherical nanoparticles with larger sizes and thus the characteristic absorption should change to single peak centered at about 400 nm. Based on the research results, mathematical models are proposed for explaining the formation and morphology changes of silver nanorods. The morphology evolution of silver nanorods may be important and can be used as a reference for preparing silver nanorods, nanowires and other anisotropic nanomaterials.
    Physica E Low-dimensional Systems and Nanostructures 11/2014; 64:211–217. DOI:10.1016/j.physe.2014.07.029 · 1.86 Impact Factor
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    ABSTRACT: In this study, a series of chitosan-stabilized nano zero-valent iron (CNZVI) composites with different amounts of chitosan were prepared and characterized by Fourier transform infrared spectra, X-ray diffraction, and transmission electron microscopy. The adsorption capacity of these composites was evaluated by the removal experiment of cadmium ion (Cd2+) from aqueous solution. These results showed that the as-prepared CNZVI8 composite with loose aggregate structure has the maximum adsorption capacity for Cd2+. Furthermore, batch adsorption experiments of Cd2+ on CNZVI8 composite were performed under various conditions, such as contact time, adsorbent dosage, initial Cd2+ concentration, and the initial pH of solution. The data revealed that the maximum adsorption capacity of CNZVI8 is 124.74 mg/g. The removal efficiency of Cd2+ increased with the increase in solution pH value, and reaches 99.9% at pH 6. In addition, the adsorption isotherm and the adsorption kinetics of Cd2+ on CNZVI8 were also investigated, suggesting that the isothermal data were well fitted to the Langmuir model and the kinetic data were well suitable to the pseudo-second-order kinetic model.
    Desalination and water treatment 07/2014; DOI:10.1080/19443994.2014.934727 · 0.99 Impact Factor
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    ABSTRACT: In this study, silver–graphene nanocomposites (SGNs) were successfully prepared by spontaneous reduction of silver ions and graphene oxide. Silver nanoparticles (about 30 nm) with narrow size distribution were distributed randomly on the surface of graphene. Different amounts of SGNs were introduced into silver flakes filled electrical conductive adhesives (ECAs) to study the effect of SGNs on the properties of the ECAs. The results showed that the volume resistivity of the ECAs decreased first and then increased with the increase of weight ratios of SGNs to silver flakes. While the weight ratio of SGNs to silver flakes was 20:80 (%), the resistivity reached the lowest value of 2.37 × 10−4 Ω cm. The lap shear strength decreased with the increase of the content ration of SGNs. And when the weight ratio of SGNs to silver flakes was 20:80 (%), the lap shear strength of ECA was about 10 MPa. According to the thermogravimetric analysis, the addition of SGNs can cause a slight decrease in the thermal stability of the ECA. In summary, SGNs are the promising candidates for the conductivity improvement of silver flakes filled electrical conductive adhesives.
    Journal of Materials Science Materials in Electronics 03/2014; 25(3). DOI:10.1007/s10854-013-1671-7 · 1.97 Impact Factor
  • Ceramics International 03/2014; 40(2):3503-3509. DOI:10.1016/j.ceramint.2013.09.079 · 2.09 Impact Factor
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    ABSTRACT: Cetyltrimethylammonium bromide rod-like micelles were employed as soft template to prepare one-dimensional and two-dimensional silver nanostructures by a seed-mediated growth method. The results indicate that the acidity-basicity of the solution plays an important role in the formation of silver nanorods and net-like nanostructures. Silver ions are not reduced at the pH lower than the pKa 1 4.1 of ascorbic acid. The lower NaOH concentration (e.g., 4.5 mM) is favorable to the growth of the seed crystals and the self-assembly of silver nanoparticles to form silver net-like nanostructures. The optimal pH for the formation of silver net-like nanostructures is about 6.0. The time-resolved UV-Vis spectra show that the seed crystals grow gradually with time from small nanocrystals to big nanoparticles, short nanorods and net-like nanostructures under the template effect of CTAB micelles. The higher NaOH concentration gives a higher reduction rate of silver ions to facilitate the formation of silver nanorods. The aspect ratio of silver nanorods increases with NaOH concentration from 6.75 mM to 11.25 mM and decreases with NaOH concentration from 11.25 mM to 18.00 mM. However, only silver nanospheres are formed at the pH near to and more than the pKa 2 11.8 of ascorbic acid. The optimal pH range of the solution for the formation of silver nanorods is from 9.56 to 10.80. Furthermore, the lower concentration of crystal seeds also facilitates the formation of silver nanostructures. These results will help in studying the synthesis of anisotropic metal nanomaterials by a seed-mediated growth method.
    Science of Advanced Materials 02/2014; 6(2):304-311. DOI:10.1166/sam.2014.1716 · 2.91 Impact Factor
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    ABSTRACT: Compared with other inorganic antibacterial agents, magnesium oxide (MgO) nanopowders exhibit a unique antibacterial mechanism and various advantages in applications, having attracted extensive attention. In this study, MgO nanopowders doped with different ions (Li+, Zn2+ and Ti4+) were synthesized by a sol-gel method, respectively. The structures and morphologies of the as-obtained precursors and nanopowders were characterized and confirmed by X-ray diffraction (XRD), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS) analysis. The influence of three metal ions doping on the antibacterial properties of MgO nanopowders was also investigated by their bactericidal activity against Escherichia coli (E. coli, ATCC 25922) using the broth microdilution method and the agar method. The results show that Li-doped MgO exhibits better antibacterial activity, Zn-doped and Ti-doped MgO display poorer antibacterial activity than pure MgO. It can be concluded that the influence of different ions doping on the antibacterial properties of MgO mainly lies on oxygen vacancies and basicity of nanopowders.
    Applied Surface Science 11/2013; 284:726-731. DOI:10.1016/j.apsusc.2013.08.001 · 2.54 Impact Factor
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    ABSTRACT: Magnesium oxide (MgO) nanopowders were synthesised by a sol-gel method with different amounts of ammonium hydroxide (NH3·H2O) and characterised by a combination of thermo gravimetric analysis, X-ray diffraction and transmission electron microscopy. It was found that the structure and morphology of MgO nanopowders can be regulated by the addition of NH3·H2O. When an appropriate amount of NH3·H2O was added into the reaction system, plate-like nanoMgO was obtained. The antibacterial activity of MgO nanoplates was also investigated by the minimum inhibition concentration (MIC) test and bactericidal efficacy against Escherichia coli (E. coli, ATCC 25922). The tested results revealed that the MgO nanoplates have great antibacterial effect with an MIC value of 600 mg/l and the bactericidal rate was about 99.8% at a concentration of 500 mg/l. Furthermore, the effect of NH3·H2O on the structure and morphology of MgO nanopowders and on the growth mechanism are briefly discussed. The hydroxide ion of NH3·H2O, in favour of Mg(OH)2 generation in the precursors, is essential for the formation of MgO nanoplates.
    Micro & Nano Letters 09/2013; 8(9):479-482. DOI:10.1049/mnl.2013.0348 · 0.80 Impact Factor
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    ABSTRACT: Silver nanoparticles (Ag NPs) were prepared via a wet-chemical method in the presence of poly(vinyl pyrrolidone) (PVP) without other reducing agents at room temperature. The influence of the addition of water on the preparation of Ag NPs was investigated. It was found that water addition has a significant influence on the reduction reaction, resulting in changes of shape, size and optical properties of the particles. When large amounts of water were added, the reduction rate was very slow. However, when small amounts of water were used, the opposite effects on the reaction process were observed, initial inhibition effect and final promotion effect. Two main possible mechanisms were proposed to explain the opposite effects of two reaction stages with small amounts of water addition: (1) the initial inhibition effect was induced by free oxygen in water, which would react preferentially with the reducing species in the system; (2) the promotion effect thereafter may be due to the differences of chain extension of PVP molecules and electron transfer rate in ethanol and water.
    Journal of Nanoscience and Nanotechnology 06/2013; 13(6):4084-9. DOI:10.1166/jnn.2013.7142 · 1.34 Impact Factor
  • Fazhe Sun, Fatang Tan, Wei Wang, Xueliang Qiao
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    ABSTRACT: The unique bouquet-like ZnO arrays were successfully synthesized via a two-step route. First, flower-like ZnO arrays were prepared by a hydrothermal reaction. Then the bouquet-like structure was obtained by the selective etching of the ZnO nano-flowers in NaCl aqueous solution. Each ZnO bouquet was composed of many tube-like petals radiating from the center outwards. Based on the experimental evidences, a possible mechanism involving face-selective etching and defect-selective etching was proposed for the formation of bouquet-like ZnO arrays. It was found that the distribution of defects played a critical role in the structure of petals of ZnO bouquets. Photoluminescence (PL) spectrum of the bouquet-like ZnO arrays exhibited two emission bands, including a strong ultraviolet (UV) emission at 382 nm and a weak visible emission band centered at 532 nm.
    Materials Letters 05/2013; 99:176–179. DOI:10.1016/j.matlet.2013.03.042 · 2.27 Impact Factor
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    ABSTRACT: The highly pure nano-silver sols were prepared by an electrolysis method using two highly pure silver flakes as electrodes and deionized water as electrolytic solution, and PVP served as stabilizer. The effects of PVP content, electrolytic time and current density on the colloidal silver nanoparticles were researched. The results indicate that as-synthesized particles were spherical about 1∼3 nm in size, and monodispersed and its concentration reached to 130 μg/g under the condition of 5.0 wt% PVP with current density about 1∼2 mA/cm2 for 150 min. Moreover, the nano-silver sol had such an excellent stability that it had not any change though it was placed in dark at room temperature for 6 months.
    Rare Metal Materials and Engineering 02/2013; 42(2):249–253. DOI:10.1016/S1875-5372(13)60040-5 · 0.16 Impact Factor
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    ABSTRACT: ZnO nanorods have been successfully prepared at low temperature (60 °C) in the presence of ammonia via a simple aqueous solution-based chemical approach. After calcination at 300 °C, many unique pitted structures are found on the surface of ZnO nanorods, although the shape and size of ZnO nanorods have almost no changes. Furthermore, the pit-structured ZnO nanorods exhibit higher photocatalytic activity for methylene blue photodegradation with a rate constant (k) of 0.01402 min−1, which is about 3 times more than that of uncalcined sample. The formation of the pitted structures is presumably attributed to the decomposition of a trace amount of ZnO(NH3)n complex implanted into ZnO crystals. In addition, a photocatalytic mechanism is proposed to explain the enhanced photocatalytic activity of the pit-structured ZnO nanorods.
    RSC Advances 01/2013; 3(43):20054. DOI:10.1039/c3ra42874e · 3.71 Impact Factor
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    ABSTRACT: Controllable synthesis of uniform silver particles was investigated via rapid mixing of l-ascorbic acid aqueous solution and silver–amine complex aqueous solution in the presence of polyvinyl pyrrolidone (PVP) at room temperature. It is found that the addition of nitric acid and aqueous ammonia into the reaction solution has a crucial effect on the final morphology of the resulting products. Furthermore, the effect of aqueous ammonia addition on the morphology and size of silver particles was investigated in this study. Smooth silver particles with the diameters ranging from 0.2 μm up to 2 μm were obtained by varying the concentration of aqueous ammonia. The synthesis method was of excellent stability in the range of 20–40 °C, which can be considered as an effective method for large-scale preparation of mono-dispersive silver particles with a wide size range.
    Powder Technology 01/2013; 233:91–95. DOI:10.1016/j.powtec.2012.08.036 · 2.27 Impact Factor
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    ABSTRACT: Large-scale ZnO arrays with a series of morphologies, including nest-like, tower-like, and flower-like samples, have been successfully synthesized by a simple hydrothermal method. The morphologies of the obtained ZnO arrays can be conveniently tailored by changing seeding conditions. The samples were characterized using X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and photoluminescence (PL) spectroscopy. Their PL spectra depend on their morphologies and defects density. The morphology-dependent photocatalytic performances were studied by analyzing the degradation of methylene blue (MB) in aqueous solution. The nest-like ZnO arrays exhibited higher photocatalytic activity than tower-like and flower-like ZnO arrays.
    Applied Surface Science 12/2012; 263:704-711. DOI:10.1016/j.apsusc.2012.09.144 · 2.54 Impact Factor
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    ABSTRACT: Ag/ZnO heterostructure nanocrystals were successfully synthesized by a novel method using glucose as a reducing agent. The Ag/ZnO heterostructure nanocrystals were composed of ZnO nanorods and metallic Ag nanoparticles (10–30 nm). The formation mechanism of Ag/ZnO heterostructure nanocrystals was clearly discussed. The photocatalytic performance of Ag/ZnO heterostructure nanocrystals was evaluated by analyzing the degradation of methylene blue (MB) under UV illumination. The Ag/ZnO heterostructure nanocrystals showed an enhanced photocatalytic performance, and the optimized Ag content was investigated. Besides, no obvious loss of photocatalytic activity was observed after five cycles, indicating the excellent photostability of Ag/ZnO heterostructure nanocrystals. This synthesis method has great potential for the industrial production of Ag/ZnO heterostructure nanocrystals as photocatalysts.
    Materials Research Bulletin 11/2012; 47(11):3357–3361. DOI:10.1016/j.materresbull.2012.07.025 · 1.97 Impact Factor
  • Journal of Materials Science 10/2012; 47(20):7262-7268. DOI:10.1007/s10853-012-6676-8 · 2.31 Impact Factor
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    ABSTRACT: Hybrid nanocomposite films of magnesium oxide (MgO) in fluorinated polyimide (PI) from 4, 4′-(hexafluoroisopropylidene) diphthalic anhydride (6FDA) and 4, 4′-Diaminodiphenyl ether (ODA) have been successfully fabricated via an in situ sol–gel polymerization technique. The MgO content in hybrid films was varied from 0 to 5 wt%. The hybrid films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), ultraviolet–visible (UV–Vis) spectroscopy and thermal gravimetric analyses (TGA). The results of FTIR, XRD and FESEM showed that the MgO nanoparticles were well dispersed in the polymer matrix due to the coordination between the carbonyl group of polymers and Mg atom, and the as-prepared hybrid films exhibited excellent optical transparency in the visible region and good UV-shielding properties in the UV region. Although the thermal stability of the hybrid films is slight inferior to pure PI, it is still good for the practical application below the temperature of 300 °C.
    Journal of Sol-Gel Science and Technology 09/2012; 63(3). DOI:10.1007/s10971-012-2811-x · 1.55 Impact Factor
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    ABSTRACT: Silver nanocrystals with controlled particle size were prepared by reduction of silver nitrate with sodium borohydride in the presence of trisodium citrate and then silver nanorods were synthesized by using the nanocrystals as seeds. The aging has obvious influence on the small nanocrystals but little influence on the large nanocrystals, implying different structural defects on the crystal surfaces of the two kinds of nanocrystals. The use of silver nanocrystals prepared by addition of NaBH4 all at once and prepared at 0 °C helps produce the most silver nanorods with maximum aspect ratio. Only the smaller and slightly aged nanocrystals can be used as seeds for the formation of silver nanorods with high aspect ratio. The effects of concerned parameters of silver seeds can be applied to the synthesis of other anisotropic nanomaterials by a seed-mediated growth approach.
    Applied Surface Science 05/2012; 258(15):5909–5913. DOI:10.1016/j.apsusc.2012.02.138 · 2.54 Impact Factor
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    ABSTRACT: Here we report a facile, surfactant-free and template-free synthesis process of highly uniform dendritic silver nanostructures with high catalytic activity for the reduction of p-nitrophenol. By controlling the concentration of AgNO(3) aqueous solution and the reaction time, various shapes of silver nanodendrites (SNDs) could be obtained easily. The effects of different parameters such as concentrations of the reagents and reaction time on the morphology and structure of as-prepared tree-like nanostructures have also been investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). Also, the X-ray photoelectron spectroscopy (XPS) has been used to identify the oxidation state of SNDs. In addition, the catalytic activity of the as-prepared SNDs samples at 200 mM AgNO(3) aqueous solution was evaluated by a redox reaction of p-nitrophenol in the presence of an excess amount of NaBH(4). It was found that the highly symmetrical SNDs with roughly 60-120 nm in stem and branch diameter and 3-12 μm in length obtained after 120 s reaction time do have higher catalytic activity than other SNDs prepared at different reaction time, several times stronger catalytic activity in the sodium borohydride reduction of p-nitrophenol to p-aminophenol, compared to some other silver nanoparticles reported in literature. The crystallinity provided by X-ray diffraction (XRD) analysis indicates that the improvement of the crystallinity is also very crucial for SNDs' catalytic activities. The SNDs are very promising catalytic candidates for the reduction of p-nitrophenol because of easily simple preparation route and high catalytic activity.
    Journal of hazardous materials 03/2012; 217-218:36-42. DOI:10.1016/j.jhazmat.2012.01.056 · 4.33 Impact Factor
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    ABSTRACT: A modified chemical-precipitation method is proposed to synthesize MgO nanopowders with high crystallinity at a low temperature of 400 degrees C using acetic acid as a modifier. The as-obtained intermediates and final products were investigated by Fourier-transformed infrared spectroscopy, thermogravimetric analysis, X-ray diffraction and transmission electron microscopy, respectively. The influence of acetic acid in the MgO preparation process was also investigated by a comparison of the samples without acetic acid, and the mechanism of acetic acid modification is also proposed. The carboxyl group of acetic acid could coordinate with Mg atom in a monodentate mode to form a new organic ligand intermediate Mg(OH)(OCOCH3), which facilitates the thermal decomposition of the intermediate at low temperature and enhances the crystallization of MgO.
    Journal of Nanoscience and Nanotechnology 03/2012; 12(3):1919-23. DOI:10.1166/jnn.2012.5669 · 1.34 Impact Factor