Zhenqiang Xi

Zhejiang University of Science and Technology, Hang-hsien, Zhejiang Sheng, China

Are you Zhenqiang Xi?

Claim your profile

Publications (33)83.97 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Anatase TiO2/multi-walled carbon nanotubes (TiO2/MWCNTs) hybrid nanofibers (NFs) film was prepared via a facile electrospinning method. Dye-sensitized solar cells (DSSCs) based on TiO2/MWCNTs composite NFs photoanodes with different contents of MWCNTs (0, 0.1, 0.3, 0.5, 1 wt.%) were assembled using N719 dye as sensitizer. Field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), X-ray diffractometer (XRD), and Raman spectrometer were used to characterize the TiO2/MWCNTs electrode films. The photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were carried out to evaluate the photoelectric properties of the DSSCs. The results reveal that the energy conversion efficiency is greatly dependent on the content of MWCNTs in the composite NFs film, and a moderate incorporation of MWCNTs can substantially enhance the performance of DSSCs. When the electrode contains 0.3 wt.% MWCNTs, the corresponding solar cell yield the highest efficiency of 5.63%. This efficiency value is approximately 26% larger than that of the unmodified counterpart.
    Electrochimica Acta 01/2013; 87:651–656. DOI:10.1016/j.electacta.2012.09.096 · 4.50 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Samarium ions doped strontium molybdate (SrMoO4:Sm3+) nanofibers (NFs) were fabricated by a simple electrospinning process. The obtained SrMoO4:Sm3+ NFs are composed of scheelite-type tetragonal SrMoO4 phase, and the NFs have an average diameter of ca. 90 nm. Under 275 nm ultraviolet (UV) excitation, the NFs show an orange-red fluorescent property symbolized by a characteristic emission (606 nm) resulting from the 4G5/2 → 6H7/2 energy level transition of Sm3+. And the photoluminescence (PL) emissi on intensity of the SrMoO4:Sm3+ NFs is superior to that of the nanoparticles (NPs) counterpart under the same doping concentrations. The effect of Sm3+ concentrations on the 4G5/2 → 6H7/2 emission intensity was also investigated. The result reveals that the concentration quenching will occur when the Sm3+ content exceeds 2 at.%. In other words, the SrMoO4:Sm3+ NFs have an optimal luminescent performance under such a doping concentration.
    Journal of Alloys and Compounds 11/2012; 540:179-183. DOI:10.1016/j.jallcom.2012.06.025 · 2.73 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Novel TiO2/Nb2O5 core–sheath nanofibers (NFs) were prepared via co-electrospinning. Dye-sensitized solar cells (DSSCs) were assembled using TiO2/Nb2O5 NF films as photoanode. The incident photo-to-current conversion efficiency (IPCE), electrochemical impedance spectroscopy (EIS), and photocurrent–voltage (I–V) characteristics were measured to evaluate the performance of DSSCs. The TiO2/Nb2O5-based DSSCs are superior to their TiO2-based counterparts. The conversion efficiency is enhanced from 4.5 to 5.8%, which corresponds to an increase of ca. 30%. And the enhancement mechanism was discussed.
    Electrochemistry Communications 11/2012; 25(1):46–49. DOI:10.1016/j.elecom.2012.09.013 · 4.85 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Novel TiO2/ZnO core–sheath nanofibers (NFs) film was fabricated through an extraordinary coaxial electrospinning technique. Dye-sensitized solar cells (DSSCs) were assembled using the TiO2/ZnO NFs film as photoanode. FESEM, TEM, FTIR, XRD, XPS and UV–vis were used to characterize the NFs electrode film. Photocurrent–voltage (I–V) characteristic, incident photo-to-current conversion efficiency (IPCE) spectrum, and electrochemical impedance spectroscopy (EIS) measurements were performed to evaluate the DSSCs performance. The results reveal that the DSSCs based on the TiO2/ZnO core–sheath NFs are superior to their bare TiO2 NFs-based counterparts. Compared with the latter, the overall energy conversion efficiency was enhanced from 4.47 to 5.17%. And the possible mechanism for this enhancement was discussed.
    Electrochimica Acta 09/2012; 78:392–397. DOI:10.1016/j.electacta.2012.06.034 · 4.50 Impact Factor
  • Z. Xi · H. Zeng · N. Liao · L. Shi · H. Huang · S. Guo · N. Wang · D. Jin · L. Wang
    [Show abstract] [Hide abstract]
    ABSTRACT: n-Type cuprous oxide was synthesized by controlling the bath pH of the electro-deposition. Thereafter, cuprous oxide films were annealed in nitrogen at different temperatures. The electrical properties of n-type cuprous oxide films before and after annealing were studied by the capacitance–voltage measurements. By analysis of the Mott–Schottky curves, it was found that the carrier concentration of cuprous oxide films varied with the deposition bath pH and the annealing temperature. Also, the flat-band potential shifted with the increasing annealing temperature.
    Thin Solid Films 01/2012; 520(7):2708–2710. DOI:10.1016/j.tsf.2011.11.044 · 2.13 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: Tb(3+)-doped Gd(2)O(3) (Gd(2)O(3):Tb(3+)) nanofibers were prepared via a simple electrospinning technique using poly(ethylene oxide) (PEO) and rare-earth acetate tetrahydrates (Ln(CH(3)COO)(3)·4H(2)O (Ln = Gd, Tb)) as precursors. The obtained nanofibers have an average diameter of about 80 nm and are composed of pure cubic Gd(2)O(3) phase. A possible formation mechanism for the nanofibers is proposed on the basis of the experimental results, which reveals that PEO acts as the structure directing template during the whole electrospinning and subsequent calcination process. The luminescent properties of the nanofibers were investigated in detail. The nanofibers exhibit a favorable fluorescent property symbolized by the characteristic green emission (545 nm) resulting from the 5D4-->7F5 transition of Tb(3+). Concentration quenching occurs when the Tb(3+) concentration is 3 at.%, indicating that the Gd(2)O(3):Tb(3+) nanofibers have an optimum luminescent intensity under such a doping concentration.
    Nanotechnology 01/2011; 22(3):035602. DOI:10.1088/0957-4484/22/3/035602 · 3.67 Impact Factor
  • L. Wang · L. Shi · N. Liao · H. Jia · X. Yu · P. Du · Z. Xi · D. Jin
    [Show abstract] [Hide abstract]
    ABSTRACT: Y2O3:Eu3+ red-emitting thin film phosphor was prepared by a two-step process: the cathodical deposition of thin film of yttrium hydroxide and europium hydroxide followed by an annealing process to achieve Eu3+ doped Y2O3 film. It is found that the atomic content of Eu3+ can be well controlled by simply adjusting the volume ratio of Y(NO3)3 to Eu(NO3)3 solutions. Dependence of the photoluminescence intensity on the atomic content of Eu3+ in Y2O3 was also studied. The best photoluminescence performance of Y2O3:Eu3+ thin film phosphor was achieved as atomic content of Eu3+ equal to 1.85at.%.
    Thin Solid Films 06/2010; 518(17):4817-4820. DOI:10.1016/j.tsf.2010.01.059 · 2.13 Impact Factor
  • L. Wang · L. Shi · N. Liao · H. Jia · P. Du · Z. Xi · D. Jin
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, two Tb3+ activated green phosphors: Y2O3:Tb3+ and YBO3:Tb3+ were prepared by hydrothermal method. Photoluminescence properties of both phosphors were studied in details. Both phosphors exhibit similar luminescent characteristics symbolized by the dominant green emission at 545 nm. Concentration quenching occurs at the Tb3+ concentration of 1.60 atomic% and 2.57 atomic% for Y2O3:Tb3+ and YBO3:Tb3+, respectively. Luminescence decay properties were characterized to better understand the mechanism of concentration quenching. Based on the calculation, the concentration quenching in both phosphors was caused by the dipole–dipole interaction between Tb3+ ions.
    Materials Chemistry and Physics 02/2010; 119(3):490–494. DOI:10.1016/j.matchemphys.2009.10.002 · 2.13 Impact Factor
  • L. Wang · H. Jia · X. Yu · Y. Zhang · P. Du · Z. Xi · D. Jin
    Electrochemical and Solid-State Letters 01/2010; 13(6). DOI:10.1149/1.3384079 · 2.15 Impact Factor
  • L. Wang · N. Liao · L. Shi · H. Jia · P. Du · Z. Xi · D. Jin
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, photoluminescence properties of Y2O3:Tb3+ thin-film phosphors were studied in detail. Y2O3:Tb3+ thin-film phosphors were prepared by a two-step process:electrodeposition followed by an annealing process. Photoluminescence properties of the Y2O3:Tb3+ thin-film phosphors strongly depend on the atomic content of Tb3+. The strongest photoluminescence emission was achieved with the atomic content of Tb3+ of 5.02 atom %. The photoluminescence decay behavior of the Y2O3:Tb3+ thin-film phosphors was also studied to understand the concentration quenching behavior. Based on the results and calculations, the concentration quenching of Tb3+ was caused by the dipole-dipole interaction between Tb3+ ions.
    Electrochemical and Solid-State Letters 01/2010; 13(6). DOI:10.1149/1.3381025 · 2.15 Impact Factor
  • L. Wang · N. Liao · L. Shi · H. Jia · P. Du · N. Wang · Z. Xi · D. Jin
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, Y2O3:Eu3+ thin-film phosphors were prepared by an electrodeposition method. The effect of Li+ ions on the photoluminescence properties of Y2O3:Eu3+ thin-film phosphor was studied in detail. The addition of Li+ ions could improve the photoluminescence intensity by around 3.5 times. The greatly improved photoluminescence intensity may be caused by different factors. The most likely factors are the improved crystallinity and the increased optical volume caused by the flux effect of Li+ ions.
    Electrochemical and Solid-State Letters 01/2010; 13(12):E19. DOI:10.1149/1.3489074 · 2.15 Impact Factor
  • Yuheng Zeng · Deren Yang · Zhenqiang Xi · Weiyan Wang · Duanlin Que
    [Show abstract] [Hide abstract]
    ABSTRACT: The iron precipitation in as-received Czochralski (CZ) silicon during low temperature from 300 to 700 °C was investigated. It was found that the iron precipitation rate was increased in turn from 300 to 700 °C. It was also found that the iron could form small precipitates even at low concentration. Moreover, iron precipitation was revealed as the diffusion-limited process, which could be described properly by Ham's law. This performance of iron precipitation in as-received CZ silicon was considered to be significantly influenced by the grown-in oxygen precipitates because of the fact that the grown-in oxygen precipitates could act as the heterogeneous nuclei for interstitial iron.
    Materials Science in Semiconductor Processing 08/2009; 12(4-5-12):185-188. DOI:10.1016/j.mssp.2009.10.002 · 1.76 Impact Factor
  • Fangming Cui · Lei Wang · Zhenqiang Xi · Yun Sun · Deren Yang
    [Show abstract] [Hide abstract]
    ABSTRACT: Non-crystalline copper indium disulphide (CuInS2) thin films had been deposited on ITO glass by chemical bath deposition (CBD) in acid conditions. Then polycrystalline CuInS2 films were obtained after sulfuration in sulfur atmosphere at 450 °C for 1.5 h. The films had been characterized by X-ray diffraction (XRD), scanning electronic microscopy (SEM), Raman scattering measurements and energy dispersive X-ray analysis (EDX). The optical and electrical property of the thin films was also measured. The results showed that the pure, flatness, and well crystallized CuInS2 thin films with good electrical and optical property had been obtained, meaning that the chemical bath deposition in acid conditions is suitable for the deposition of CuInS2 thin films.
    Journal of Materials Science Materials in Electronics 07/2009; 20(7):609-613. DOI:10.1007/s10854-008-9773-3 · 1.97 Impact Factor
  • L. Wang · H. Jia · X. Yu · Y. Zhang · P. Du · Z. Xi · D. Jin
    [Show abstract] [Hide abstract]
    ABSTRACT: In this work, electrodeposition is proved to be a promising method to prepare Y2O3:Eu3+ thin-film phosphors. The photoluminescence (PL) property of the Y2O3:Eu3+ thin-film phosphor strongly depends on different factors such as the crystal structure of host materials, annealing temperature, and doping concentration of Eu3+. The best PL performance of the Y2O3:Eu3+ thin-film phosphor is achieved for a sample annealed at 600 degrees C with a Eu3+ doping concentration of 1.85 atom %.
    Electrochemical and Solid-State Letters 01/2009; 12(8). DOI:10.1149/1.3141425 · 2.15 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.
    ChemInform 12/2008; 39(51). DOI:10.1002/chin.200851018
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A general hydrothermal process with use of lanthanide (III) nitrates and Na2SnO3 as precursors has been proposed for synthesizing nanocrystalline lanthanide stannates with general formula: Ln2Sn2O7 (Ln=Y, La–Yb). Stannates of all lanthanides except for the radioactive promethium were successfully synthesized. Characterization by XRD and TEM revealed that all the products were phase-pure nanocrystalline lanthanide stannates with pyrochlore-type structure. Photoluminescent properties of three samples (i.e. Tb2Sn2O7, Dy2Sn2O7 and Yb2Sn2O7) are also presented. The mole ratio of Ln(NO3)3:Na2SnO3 and hydrothermal temperature were two key factors for this general hydrothermal route.
    Journal of Alloys and Compounds 09/2008; 464(1):508-513. DOI:10.1016/j.jallcom.2007.10.024 · 2.73 Impact Factor
  • Zhenqiang Xi · Jun Tang · Hai Deng · Deren Yang · Duanlin Que
    [Show abstract] [Hide abstract]
    ABSTRACT: A model, including segregation from silicon melt to silicon crystal as well as evaporation from silicon melt to Ar atmosphere, was established for simulating the oxygen distribution in multicrystalline silicon (mc-si) ingot, which shows good agreement with the experimental results. According to this model, the oxygen distribution in the bottom of ingot is mainly determined by the evaporation of oxygen, whereas that in the top of ingot is dominated by the segregation of oxygen. Furthermore, it could be found that the Oi profiles in growth direction of ingots become more and more steeper with the increase of the exponent X.
    Solar Energy Materials and Solar Cells 11/2007; 91(18):1688-1691. DOI:10.1016/j.solmat.2007.05.024 · 5.34 Impact Factor
  • Hongliang Zhu · Deren Yang · Zhenqiang Xi · Luming Zhu
    [Show abstract] [Hide abstract]
    ABSTRACT: This work focuses on the synthesis of tetragonal zirconia (ZrO2) nanocrystallites with diameters of 5 nm by a simple hydrothermal process in the presence of hydrazine hydrate. Structural characterization of the ZrO2 products using X-ray diffraction and Raman spectroscopy revealed that the predominant crystal phase was the tetragonal phase. High-resolution transmission electron microscopy images further showed that that the diameter of the majority of the tetragonal ZrO2 nanocrystallites was <5 nm. Furthermore, we discussed the mechanism of the hydrothermal process and the critical roles of hydrazine hydrate in the hydrothermal formation of the small-sized ZrO2 nanocrystallites.
    Journal of the American Ceramic Society 03/2007; 90(4):1334 - 1338. DOI:10.1111/j.1551-2916.2007.01494.x · 2.61 Impact Factor
  • Zhenqiang Xi · Deren Yang · Jun Chen · Takashi Sekiguchi
    [Show abstract] [Hide abstract]
    ABSTRACT: The electrical properties of cast multicrystalline silicon (mc-Si) contaminated by nickel at different temperatures were investigated by means of scanning electron microscopy and electron-beam-induced current (EBIC). Generally, the recombination activity increased with annealing temperature. In comparison with Czochralski silicon contaminated by nickel, some grain boundaries in nickel-contaminated mc-Si annealed at 500°C also displayed a strong EBIC contrast of about 10%, which suggests a low concentration of nickel in mc-Si can also precipitate or segregate in the defects and increase the recombination strength of defects. Furthermore, nickel tended to precipitate in some special grain boundaries, especially for the annealing at low temperature following slow cool.
    Materials Science in Semiconductor Processing 02/2006; 9(1):304-307. DOI:10.1016/j.mssp.2006.01.052 · 1.76 Impact Factor
  • Weiyan Wang · Zhenqiang Xi · Deren Yang · Duanlin Que
    [Show abstract] [Hide abstract]
    ABSTRACT: The recombination activity of nickel in p- and n-type Czochralski silicon after rapid thermal process (RTP) in N2, O2 or Ar ambient has been investigated by the microwave photoconductivity decay technique. The effective lifetime of silicon decreases monotonically with increasing nickel in-diffusion temperature, and exhibits a step-like behavior at nickel in-diffusion temperature of 900°C, which indicates that most of nickel atoms precipitate in the bulk no matter what kind of conducting type if the annealing temperature is above 900°C under RTP. It is also found that the ambient during RTP almost has no effect on the recombination activity of nickel in silicon, which suggests point defects almost have no influence on the nickel precipitation.
    Materials Science in Semiconductor Processing 02/2006; 9(1):296-299. DOI:10.1016/j.mssp.2006.01.057 · 1.76 Impact Factor

Publication Stats

321 Citations
83.97 Total Impact Points

Institutions

  • 2010
    • Zhejiang University of Science and Technology
      Hang-hsien, Zhejiang Sheng, China
    • Zhejiang Sci-Tech University
      Ch’u-chou, Zhejiang Sheng, China
  • 2004–2009
    • Zhejiang University
      • • Department of Material Science and Engineering
      • • State Key Lab of Silicon Materials
      Hang-hsien, Zhejiang Sheng, China