Junpeng Wang

University of Jinan (Jinan, China), Chi-nan-shih, Shandong Sheng, China

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Publications (16)68.96 Total impact

  • Yunshi Liu · Junpeng Wang · Quande Che · Ping Yang · Yunlong Yue
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    ABSTRACT: Hydrophilic and hydrophobic quantum dots (QDs) including oleic acid (OA)-capped CdSe, thiodipropioyic acid (TDPA)-capped CdSe, and thioglycollic acid (TGA)-capped CdTe were incorporated into poly(vinyl pyrrolidone) (PVP) fibers via an electrospinning method using a PVP ethanol solution with PVP weight ratio of 8% which was obtained by optimizing preparation conditions. The amounts of the QDs were adjusted to investigate the effect of QD surface state on the morphologies of fibers. The QDs retained their photoluminescence (PL) peak wavelengths in PVP solutions and fibers. The PVP fiber with aqueous CdTe QDs was fabricated by dispersing QDs in water while the hydrophobic ones were firstly dispersed in hexane. With increasing the amount of CdSe QDs, the PL intensity of the fibers was gradually enhanced. In addition, CdSe nanorods were characterized by evident unevenness and local enrichment in the fibers because of rod morphology and properties of TDPA ligand. The fiber surface was rather smooth and it almost had no wrinkles.
    Nanoscience and Nanotechnology Letters 02/2015; 7(2). DOI:10.1166/nnl.2015.1911 · 1.44 Impact Factor
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    ABSTRACT: The polyvinylpyrrolidone (PVP) hybrid luminescent micro-/nanofibers doped with the novel hybrid SiO2-coated CdTe nanocrystals (HS-CdTe NCs) have been fabricated for the first time via the electrospinning technique. The morphologies and photoluminescence (PL) emissions of HS-CdTe/PVP micro-/nanofibers prepared by doping the HS-CdTe NCs with the different PL peak wavelength (571, 616, and 643 nm) in PVP fibers were investigated by optical and PL microscope. The results revealed that all the HS-CdTe/PVP hybrid fibers showed an ultralong length for several hundreds of micrometers and a relatively uniform diameter of 1000 similar to 1200 nm. The hybrid fibers displayed a wavelength-tunable PL emission, determining by the PL of doped HS-CdTe NCs. Moreover, similar to the original PL properties of HS-CdTe NCs before the electrospinning, the HS-CdTe/PVP fibers also showed a series of superior PL properties, such as narrow and symmetry PL spectrum, high, and uniform brightness. For comparison purpose, we also prepared three CdTe/PVP hybrid fibers by doping the 553 nm, 600 nm, and 633 nm PL-emitting CdTe NCs respectively in PVP electrospinning fibers. The characterization results showed that, the obtained three CdTe/PVP hybrid fibers had a basically satisfactory micro-/nanofiber morphology with a long length and relatively uniform diameter, but all the fibers exhibited very weak PL emissions. The enormous contrast in PL properties between HS-CdTe/PVP and CdTe/PVP fibers should mainly be ascribed to the different connection modes of ligands with the NCs and the passivation effect of inert hybrid silica shell on HS-CdTe. It is hopeful that the high luminescent HS-CdTe/PVP micro-/nanofibers with the tunable PL peak wavelength would be a good candidate in the optical sensor, light-emitting devices (LEDs), nanometerscale waveguides, and the other related photonic materials.
    Materials Chemistry and Physics 01/2015; 149-150:51-58. DOI:10.1016/j.matchemphys.2014.09.030 · 2.13 Impact Factor
  • Ruixia Shi · Ping Yang · Qian Ma · Junpeng Wang · Quande Che
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    ABSTRACT: The monoclinic CuO nanosheet arrays, disk-like and sheaf-like CuO have been synthesized on Cu substrate by a facile solution route in absence of surfactant at room temperature (20 °C). The thickness of sheets and morphology of CuO can be tuned by the concentration and kind of alkali. A plausible growth mechanism was proposed to account for the formation of the nanosheet arrays. Due to the different rate of nucleation and crystal growth the morphology of CuO changed with the concentration of OH– when the same alkali metal hydroxide was used during reaction. The ionic radius of alkali metal hydroxide utilized to generate [Cu(OH)4]2– ions significantly influenced the morphology of CuO. The different cation radius has different charge density, which causes the different formation rate of the copper oxide precipitates.
    Nanoscience and Nanotechnology Letters 10/2014; 6(10). DOI:10.1166/nnl.2014.1838 · 1.44 Impact Factor
  • Xiaobin Dong · Ping Yang · Junpeng Wang · Baibiao Huang
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    ABSTRACT: ZnO rhombic sheets consisting of small particles with a size range of 150–250 nm have been prepared successfully using zinc glycerolate as a template through calcining at 600 °C. The crystallinity of the small particle plays an important role toward highly efficient photocatalysis. The sheet consisting of regular ZnO particles with fewer surface defects revealed enhanced photocatalysis compared with that constructed from small ZnO nanoparticles. Monodisperse Ag2O nanoparticles were deposited on the rhombic sheet. Highly efficient photocatalysis was observed after Ag2O nanoparticle decoration under ultraviolet and visible-light irradiation for degradation of methyl orange (MO) and 2,4-dichlorophenol (2,4-DCP). The results of photocatalysis investigations demonstrated that the ZnO rhombic sheets with Ag2O/ZnO molar ratio of 1:6 had great activity for decomposing MO and 2,4-DCP. Ag2O/ZnO rhombic sheets are favorable for the separation of the photocatalyst, which is important for applications.
    ChemPlusChem 09/2014; 79(12). DOI:10.1002/cplu.201402182 · 3.24 Impact Factor
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    ABSTRACT: A Ti3+:TiO2/TiF3 hybrid was synthesized via a one-step facile solvothermal method. Due to the presence of TiF3, TiO2 contained a high concentration of Ti3+ species and Ti3+ was stabilized. The Ti3+:TiO2/TiF3 hybrid exhibited excellent visible-light photocatalytic reactivity. The electron structure of TiF3 was studied, and a photocatalytic mechanism was also proposed.
    CrystEngComm 08/2014; 16(29):6538. DOI:10.1039/c4ce00569d · 3.86 Impact Factor
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    ABSTRACT: To investigate the shell deposited kinetics, CdSe quantum dots (QDs) and nanorods (NRs) with a maximum length of 17 nm were fabricated via organic synthesis routes. CdSe with a hexagonal crystal structure (wurtzite) favors epitaxial growth on the {002} surfaces when well-controlled conditions were used. The morphologies and sizes of CdSe samples depended strongly on chemicals and temperature. In the case of 320 °C, CdSe NRs with adjusted length of 7–17 nm were obtained from trioctylphosphine oxide (TOPO) and tetradecylphosphonic acid (TDPA). In contrast, short CdSe NRs (less than 10 nm) were created from octadecylphosphonic acid (ODPA) and trioctylamine (TOA). Spherical CdSe QDs were further fabricated using stearic acid (SA) and TOPO at 300 °C. CdSe cores were coated with Cd0.5Zn0.5S and CdTe shells. Anisotropic growth occurred during shell deposition because CdS shells grown preferentially on the {001} facet of the CdSe core. In the case of CdSe core prepared from TOPO and TDPA, CdSe/Cd0.5Zn0.5S core/shell samples prepared from long CdSe NRs (more than 10 nm) revealed a peanut morphology while the core/shell samples created from short ones (less than 10 nm) exhibited a spherical morphology. All of the CdSe/Cd0.5Zn0.5S core/shell samples revealed a similar length to that of the CdSe cores. This phenomenon was also observed for the core/shell samples fabricated using CdSe NRs prepared by ODPA and TOA. This is ascribed to the well-developed crystal structure of CdSe NRs fabricated using an organic synthesis at high temperature. In contrast, this anisotropic growth did not occur when spherical CdSe QDs prepared from SA and TOPO and the shell (Cd0.5Zn0.5S) coating carried out using SA and TOA. To indicate the shell depositing process, CdSe NRs fabricated using TDPA and TOPO were coated with a CdTe shell. CdTe monomers were deposited on the middle and tip parts of the CdSe NRs to form a tetrapod-like morphology at 220 °C. This is ascribed to the large difference of structure of CdSe (hexagonal) and CdTe (zinc blende).
    Journal of Nanoparticle Research 08/2014; 16(8). DOI:10.1007/s11051-014-2524-x · 2.28 Impact Factor
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    ABSTRACT: A sol-gel SiO2 film prepared from 3-aminopropyltrimethoxysilane (APS) has been developed as an excellent medium to encapsulate both hydrophobic and hydrophilic quantum dots (QDs). The film was fabricated by spin and dip coating on flat substrates as well as by a spraying approach on various substrates with a 3dimensional (3D) surface. Pre-heat-treatment of the substrate plays an important role for creating homogeneous films on a 3D surface. In the case of aqueous CdTe and ZnSe0.9Te0.1 QDs, APS did not decrease the photoluminescence (PL) efficiency of the QDs. For hydrophobic QDs, a phase transfer from oil to water phase was first performed through the ligand exchange process between APS and the capping agent. By mixing QDs with different emitting colors, silica gel with white-light emission was obtained. Based on hydrophobic and hydrophilic QDs, white-light-emitting diodes with adjustable chromaticity coordinates were fabricated using a UV-emitting InGaN chip as excitation source. Because of the facile preparation procedure, high stability, and high PL efficiency, the magic film shows great potential for use in white-lighting-emission applications.
    RSC Advances 01/2014; 4(39):20358. DOI:10.1039/c4ra01739k · 3.84 Impact Factor
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    ABSTRACT: Stable Ti(3+) self-doped TiO(2) with tunable phase composition and highly efficient visible-light photoactivity (ca. 32.7 times stronger than an undoped sample for ˙OH formation) was synthesized via a facile metallic zinc-assisted method. The surface Ti(3+) species can be stabilized by Zn doping, and the photocatalytic selectivity can be regulated by the phase composition.
    Chemical Communications 12/2012; 49(9). DOI:10.1039/c2cc37976g · 6.83 Impact Factor
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    ABSTRACT: Oxygen vacancies in crystal have important impacts on the electronic properties of ZnO. With ZnO(2) as precursors, we introduce a high concentration of oxygen vacancies into ZnO successfully. The obtained ZnO exhibits a yellow color, and the absorption edge shifts to longer wavelength. Raman and XPS spectra reveal that the concentration of oxygen vacancies in the ZnO decreased when the samples are annealed at higher temperature in air. It is consistent with the theory calculation. The increasing of oxygen vacancies results in a narrowing bandgap and increases the visible light absorption of the ZnO. The narrowing bandgap can be confirmed by the enhancement of the photocurrent response when the ZnO was irradiated with visible light. The ZnO with oxygen vacancies are found to be efficient for photodecomposition of 2,4-dichlorophenol under visible light irradiation.
    ACS Applied Materials & Interfaces 07/2012; 4(8):4024-30. DOI:10.1021/am300835p · 6.72 Impact Factor
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    ABSTRACT: A new class of AgCl microstructures, concave cubes, with preferential overgrowth along <110> and <111> directions, has been prepared in a monodisperse fashion by a wet chemical oxidization method. With high-index facets exposed, the concave cubic AgCl exhibits higher photocatalytic activity in O(2) evolution than cubic ones.
    Chemical Communications 03/2012; 48(29):3488-90. DOI:10.1039/c2cc30766a · 6.83 Impact Factor
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    ABSTRACT: We report a facile and simple way to synthesize graphene@TiO 2 nanocomposites with controlled crystal facets by a one-pot hydrothermal process. By controlling the concentrations of the starting materials and reaction times, graphene@TiO 2 nanocomposites with various exposed crystal facets can be obtained. The surface states and the growth process of graphene@TiO 2 nanocomposites have been studied. Owing to the exposed high-reactive crystal facets and high dispersities of TiO 2 nanocrystals on graphene surfaces, the as-prepared sample exhibited enhanced photocatalytic activities over graphene@P25 nanocomposites.
    CrystEngComm 03/2012; 14(5). DOI:10.1039/C1CE06193C · 3.86 Impact Factor
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    ABSTRACT: A novel Ag/AgBr/BiOBr hybrid was prepared by a rational in situ ion exchange reaction between BiOBr hierarchical microspheres and AgNO(3) in ethylene glycol followed by light reduction, which displayed superior visible light driven photocatalytic activities in sterilization of pathogenic organism and degradation of organic dye compared to N-doped P25.
    Chemical Communications 07/2011; 47(25):7054-6. DOI:10.1039/c1cc11525a · 6.83 Impact Factor
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    ABSTRACT: (GaN)1−x(ZnO)x solid solutions are potential photocatalysts for water splitting and environmental decontamination under visible light. Solid solutions prepared by the traditional method are not effective because of their low Zn content (x < 0.5). Here, we show that Zn-rich solid solutions (0.5 < x < 0.8) are readily prepared by the nitridation of layered double hydroxides (LDHs) containing Zn2+ and Ga3+ ions, and that the Zn content is easily adjusted by changing the Zn/Ga ratio of the LDH precursors. The band gap of (GaN)1−x(ZnO)x decreases gradually from 2.60 eV at x = 0.46 to 2.37 eV at x = 0.81. The Zn-rich solid solutions absorb strongly above 500 nm, and these solutions loaded with 1 wt% Pt are found to be efficient for photoreducing Cr6+ ions under visible light.
    Journal of Materials Chemistry 03/2011; 21(12):4562-4567. DOI:10.1039/C0JM04277C · 7.44 Impact Factor
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    ABSTRACT: Visible-light response C, N-codoped TiO2 nanotubes with high aspect ratios were prepared by a two-step method. First the TiO2 nanotubes were synthesized by an ion-exchange method, and then the nanotubes were calcined at different temperatures with melamine as nitrogen and carbon source. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV-vis diffusive reflectance spectroscopy (DRS), scanning electron microscopy (SEM), and N2 adsorption-desorption isotherms were employed to characterize the as-prepared samples. The results show that the nanotubular structure is destroyed when the calcination temperature is higher than 823 K. Further increase the temperature to 923 K, TiO2 is reduced to TiO. The photocatalytic activity of the codoped TiO2 nanotubes/nanorods was evaluated by degradation of Rhodamine B under visible-light irradiation (> 420 nm). Compared with N doped P25, these codoped TiO2 nanotubes/nanorods possess a superior photocatalytic acticity, owing to the synergistic effects of the nitrogen and carbon co-doping.
    Rare Metals 03/2011; 30(1). DOI:10.1007/s12598-011-0261-1 · 0.81 Impact Factor
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    ABSTRACT: A new plasmonic photocatalyst Ag@AgCl, which has silver nanoparticles (NP) deposited directly onto the surface of AgCl particles, was developed. A powder X-ray diffraction (XRD) pattern of the as-prepared Ag@AgBr sample shows the coexistence of Ag and AgBr. 40% of the IPA is oxidized to CO2 after irradiating the IPA solution over Ag@AgBr for only 5 min. The results also show that the decomposition of MO dye over Ag@AgBr is completed after irradiation for 10 min, but that over Ag@AgCl takes 15 min. The MO concentration is found to remain unchanged as a function of the irradiation time, demonstrating that Ag@AgBr is a photocatalyst active under visible light. Compared to Ag@AgCl, Ag@AgBr is found to have a weaker absorption in visible light, and the oxidization ability of Br is weaker than Cl.
    Chemistry - A European Journal 02/2009; 15(8):1821-4. DOI:10.1002/chem.200802327 · 5.70 Impact Factor
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    ABSTRACT: Photocatalysts that are active under sunlight are extreme- ly important in connection with removing organic pollutants in the environment. Desirable photocatalysts are those that can carry out complete decomposition of organic pollutants at low levels. (1) The most extensively studied photocatalyst, TiO2, has a large band gap (i.e., 3.2 eV for anatase and 3.0 eV for rutile) and hence absorbs only the UV light, which accounts for only 4 % of the total sunlight, to gener- ate charge carriers for promoting the surface redox reac- tions. Due to this inherent property of TiO2, its practical ap- plications are rather limited. To effectively utilize the visible light that constitutes 43 % of the total sunlight, it is impor- tant to find a photocatalyst that is active and efficient under visible light. Much effort has been devoted to developing "second-generation" TiO2 (2) and other narrow band gap semiconductors (3) that can absorb visible light. Photocata- lysts active under visible light are not necessarily limited to semiconductors with a narrow band gap, but can include semiconductors with a large band gap that can work syner- getically with nanoparticles of a noble metal.
    Chemistry - A European Journal 01/2009; 15(8):1821 - 1824. · 5.70 Impact Factor