Mingwang Shao

Soochow University (PRC), Wu-hsien, Jiangsu Sheng, China

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Publications (106)378.38 Total impact

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    ABSTRACT: Ruthenium nanoparticles modified silicon nanowires (Ru/SiNWs) were prepared by directly reducing Ru ions with Si-H bonds. The composites with different content of Ru (denoted as Ru/SiNW-x, x means the relative molar ratio of Ru to SiNW) were evaluated as electrocatalysts for the hydrogen evolution reaction (HER). Ru/SiNW-42.9 showed excellent electrocatalytic activity in the oxygen-free 0.5 M H2SO4 medium. The Tafel slope of Ru/SiNW-42.9 was 81 mV/decade, indicating its catalytic effect was even better than pure Ru particles. SiNWs modified with proper content of Ru may be a promising electrocatalyst for HER.
    Electrochemistry Communications 01/2015; · 4.29 Impact Factor
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    ABSTRACT: Uniform and dense Au nanoparticles grown on Ge (Au/Ge) were fabricated by a facile galvanic displacement method and employed as surface-enhanced Raman scattering (SERS) substrates. The substrates exhibited excellent reproducibility in the detection of rhodamine 6G aqueous solution with a relative standard deviation of <20%. The substrate showed a high Raman enhancement factor of 3.44 × 106. This superior SERS sensitivity was numerical confirmed by the three-dimensional finite-difference time-domain method, which demonstrated a stronger electric field intensity (|E/E0|2) distribution around the Au nanoparticles grown on Ge. This facile and low-cost prepared Au/Ge substrate with high SERS sensitivity and reproducibility might have potential applications in monitoring in situ reaction in aqueous solution. Copyright © 2014 John Wiley & Sons, Ltd.
    Surface and Interface Analysis 12/2014; · 1.39 Impact Factor
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    ABSTRACT: There is a strong correlation between the surface enhanced Raman scattering (SERS) enhancement factor (EF), the excitation wavelength, and the feature properties (composition, size, geometry, and analytes). The prediction of the EF of specific substrates, crucial to the quantitative SERS detection, is however still very difficult. The present work presents smart liquid SERS substrates consisting of suspensions of Fe3O4/Au nanoparticles, which provide high spot-to-spot uniformity, reproducibility and good reversibility. The EF of these substrates can be reversibly tuned by applying an external magnetic field. The EF magnetic tuning is within 2 orders of magnitude per substrate in the range of 10(4)-10(7). The ability to reversibly adjust the SERS EF enables to reduce EF variations caused by external effects such as substrate-to-substrate differences and long-term-storage degradation. This improves the quantitative detection of analytes and might be a significant step forward in employing SERS for practical applications.
    Scientific Reports 11/2014; 4:7204. · 5.08 Impact Factor
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    ABSTRACT: A two-step galvanic displacement reaction was employed to synthesize Ag-Au nanoparticles grafted on Ge wafer due to the different equilibrium potentials: the Ge wafer was employed to reduce silver ions and grow Ag nanoparticles first; and then it reduced gold ions and grew Au nanoparticles among the gaps of Ag nanoparticles. When they were employed as SERS substrates to detect 200 random spots, to the best of our knowledge, the lowest relative standard deviation (RSD) of less than 7% was obtained by using Rhodamine 6G (1 × 10-9 M) as probe molecules in the aqueous detection. Crystal violet solution (1 × 10-8 M) was also detected with an ultra low RSD of less than 8%. The result of the electric field distribution by the finite difference time domain simulation further explained the distinguished sensitivity and uniformity of these substrates. The high uniformity and reproducibility of this SERS substrate may benefit SERS quantitative detection in biology field in the future.
    J. Mater. Chem. C. 11/2014;
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    ABSTRACT: This work presents a method of generating electric current based on the defects of few-layer boron nitride nanosheets (BNNSs). The density functional theory calculations showed that the atomic charge of B atom in acetone was more positive than in water. The electrostatic force microscopy measurements illustrated that the local electrical potential was 0.35 mV in acetone, while the potential signal was very difficult to be captured when using water as the dispersant. This effect was further demonstrated by the performance of the acoustic energy harvesting nanogenerator: the BNNSs were assembled into a film when dispersed in acetone and then integrated into the generator device, generating average output current of about 0.98 nA, which was much better than 0.2 nA, the average output current of another device with water as the dispersant. These results demonstrated that solvent effects made the as-prepared BNNSs carry net charges, which could be utilized to harvest acoustic energy and generate current.
    ACS Applied Materials & Interfaces 11/2014; · 5.90 Impact Factor
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    ABSTRACT: Gamma ray irradiation improved the performance of gas sensor based on the AgFeO2 nanoparticles including sensitivity and optimum operating temperature, which might be ascribed to the generation of defects.
    Journal of Solid State Chemistry 11/2014; 219:228–231. · 2.20 Impact Factor
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    ABSTRACT: Ag/Ag2SnO3 nanoparticles were synthesized by irradiating Ag2SnO3 with different doses of gamma ray ranging from 0 to 500 kGy. The irradiated products were employed to detect two reducing gases (ethanol and nitromethane) and one oxidizing gas (acetic acid). The response was found to be dependent on irradiation dose, which influenced the content of Ag. The results showed that the best gas-sensing performance was achieved at the dose of 400 kGy: the responses were enhanced 9, 6.3 and 10.6 folds compared with the unirradiated Ag2SnO3 for ethanol, nitromethane and acetic acid, respectively.
    J. Mater. Chem. C. 10/2014;
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    ABSTRACT: In this paper, Au/CuS composites were fabricated by a two-step method based on a facile solvothermal approach combined with the in situ reduction. It was demonstrated that the Au/CuS composite not only exhibited excellent peroxidase-like catalytic activity in the oxidation of the typical peroxidases (o-phenylenediamine and diaminobenzidine), but also showed promising SERS performance with remarkable sensitivity and high reproducibility. Based on these properties, the bi-functional Au/CuS composite was employed both as a catalyst for degrading a pollutant (Rhodamine 6G) and a SERS substrate for real-time monitoring of the degradation process quantitatively.
    Nanoscale 06/2014; · 6.74 Impact Factor
  • Mingfa Peng, Hongyan Xu, Mingwang Shao
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    ABSTRACT: Surface-enhanced Raman scattering effect was demonstrated on nanomaterial array, which was fabricated by Au deposition on the profile of etched Si nanowires. Ultrasensitive surface-enhanced Raman scattering signals from the nanoside array structures were observed with the enhancement factor of 2.3 × 109, even though the concentration of the R6G was as low as 1 × 10−11 M. Moreover, the Raman enhancement effect of nanoside array was proved to be 6.2 times compared with the counterpart of nanoplane array, which suggested the potential applications in ultrasensitive surface-enhanced Raman detection.
    Applied Physics Letters 05/2014; 104(19):193103-193103-4. · 3.52 Impact Factor
  • Haiyang Lin, Qi Shao, Fei Hu, Hui Wang, Mingwang Shao
    Thin Solid Films 04/2014; 558. · 1.87 Impact Factor
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    ABSTRACT: The finite-difference time-domain (FDTD) method was employed to simulate the electric field distribution for noble metal (Au or Ag)/semiconductor (Ge or Si) substrates. The simulation showed that noble metal/Ge had stronger SERS enhancement than noble metal/Si, which was mainly attributed to the different dielectric constants of semiconductors. In order to verify the simulation, Ag nanoparticles with the diameter of ca. 40 nm were grown on Ge or Si wafer (Ag/Ge or Ag/Si) and employed as surface-enhanced Raman scattering substrates to detect analytes in solution. The experiment demonstrated that both the two substrates exhibited excellent performance in the low concentration detection of Rhodamine 6G. Besides, the enhancement factor (1.3 × 10(9)) and relative standard deviation values (less than 11%) of Ag/Ge substrate were both better than those of Ag/Si (2.9 × 10(7) and less than 15%, respectively), which was consistent with the FDTD simulation. Moreover, Ag nanoparticles were grown in-situ on Ge substrate, which kept the nanoparticles from aggregation in the detection. To data, Ag/Ge substrates showed the best performance for their sensitivity and uniformity among the noble metal/semiconductor ones.
    Scientific Reports 02/2014; 4:4052. · 5.08 Impact Factor
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    ABSTRACT: Indium vanadate (InVO4) nanoribbons were irradiated with various doses of gamma ray irradiation. The results revealed that the crystal structure remained unchanged after irradiation while the UV–Vis spectra underwent a red-shift with increasing irradiation dose. In addition, gamma ray irradiation enhanced the sensibility of InVO4-based sensors for ammonia testing. The improved properties of InVO4-nanobased sensors exposed to irradiation might be ascribed to the defects introduced by gamma ray, making gamma ray irradiation a good approach for material modification.
    Journal of Materials Science Materials in Electronics 01/2014; 25(1). · 1.97 Impact Factor
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    ABSTRACT: In this paper, pure metastable phase iron vanadate (FeVO4-II) ultrathin nanosheets (50 nm in thickness) with exposed {010} facets were obtained by a mild hydrothermal process, without the use of any template or organic surfactant. The photocatalytic rate of the FeVO4-II {010} facets was measured taking advantage of their unique morphology. Furthermore, the FeVO4-II catalyst could be easily separated and reused, simply by applying an external magnetic field. In addition, with their n-type semiconductor structure, FeVO4 ultrathin nanosheets exhibited gas-sensing for an ethanol trace.
    CrystEngComm 01/2014; 16(2):270. · 3.86 Impact Factor
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    ABSTRACT: A visible light-enhanced gas sensor based on cadmium selenide (CdSe) nanoribbons has been successfully developed. These nanoribbons were synthesized by a gold-catalyzed vapor-liquid-solid method and employed as visible-light-activated gas sensors for 50 to 1000 ppm ethanol at 200 °C. Visible light illumination on the surface of CdSe nanoribbons could produce more holes and increase the conductance of the sensor which significantly enhanced the gas response.
    CrystEngComm 01/2014; 16(20):4231. · 3.86 Impact Factor
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    ABSTRACT: A Cu/V2O5 composite was obtained via a simple and time-saving microwave-assisted reduction method from a single-source precursor, copper vanadate. This composite exhibited excellent SERS sensitivity and reproducibility for both Rhodamine 6G (1.0 × 10−7 M) and 4-mercaptobenzoic acid (1.0 × 10−5 M) probe molecules, with the enhancement factor of 1.9 × 106 for Rhodamine 6G. The Lewis acid-base properties of V2O5 help improve the chemical enhancement of SERS via Lewis acid-base interaction. Furthermore, the Cu/V2O5 composite was also employed to catalyze C-N and C-C bond cross coupling of the Ullmann reaction. The results demonstrated that Cu/V2O5 catalysts had a better catalytic ability toward the C-N bond (yield of 92.5%) than the C-C bond (yield of 68.8%). This SERS-active composite was hopeful in monitoring the catalytic reactions with in situ SERS technology.
    RSC Advances 01/2014; 4(13):6424. · 3.71 Impact Factor
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    ABSTRACT: The effect of gamma ray irradiation on silicon nanowires was investigated. Here, an additional defect emerged in the gamma-ray-irradiated silicon nanowires and was confirmed with electron spin resonance spectra. 29Si nuclear magnetic resonance spectroscopy showed that irradiation doses had influence on the Q4 unit structure. This phenomenon indicated that the unique core/shell structure of silicon nanowires might contribute to induce metastable defects under gamma ray irradiation, which served as a satisfactory model to investigate defects at the interface of Si/SiOx.
    Applied Physics Letters 12/2013; 104(3). · 3.52 Impact Factor
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    ABSTRACT: Silicon nanowires are important semiconductor with core/shell structure. In this work, the piezoelectric material alpha-quartz was grown in the interface of silicon nanowires by thermal treatment at 600 °C for 0.5 h. These nanowires were employed as starting materials to fabricate piezoelectric nanogenerators, which could convert kinetic energy into electrical one, exhibiting an output voltage of 36.5 V and a response current of 1.4 μA under a free-falling object of 300 g at a height of 30 cm.
    Nanoscale 10/2013; · 6.74 Impact Factor
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    ABSTRACT: A simple hydrothermal method was employed to synthesize AgFeO2 nanoparticles, which were utilized as substrates in SERS detection of Rhodamine 6G and 4-mercaptobenzoic acid. The magnetic properties of the products provided the capability of concentrating analyte molecules under an external magnetic field. The detection in aqueous solution has ensured the uniformity of the SERS signals and the reproducibility of the substrates. It was interesting that the substrates exhibited high SERS activity at Rhodamine 6G concentration of 1 × 10(-7) M with an enhancement factor of 5.1 × 10(5), showing the highest SERS effect for semiconductor substrates, which might be ascribed to the orderly orientation of AgFeO2 nanoparticles under external magnetic field.
    Nanoscale 09/2013; · 6.74 Impact Factor
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    ABSTRACT: Indium vanadate (InVO4) gas sensors were fabricated by depositing InVO4 nanoribbons aqueous suspension onto ceramic substrates. Their resistances distinctively increased in the detection of ammonia and propylamine, indicating an n-to-p semiconductor transition. This novel phenomenon of InVO4-based sensor may be ascribed to the surface doping effect: electrons were trapped by H2O and O2 and produced OH- and O2- on InVO4 surface, which resulted in holes over-compensation in InVO4 valance band. Moreover, the sufficiently large surface-to-volume ratio of these nanoribbons enables fast carrier transfer on sensor surface. The InVO4 nanoribbons-based sensors had optimum performance at room temperature and enjoyed good restorability. They also had great response to a wide range of target gas concentration, with ultrahigh sensitivities up to 1100% for ammonia, and 760% for propylamine.
    ACS Applied Materials & Interfaces 03/2013; · 5.90 Impact Factor
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    ABSTRACT: A ZnO-RGO-Au composite with bi-functional behavior was fabricated: it was employed both as a photocatalyst for degrading pollutants (Rhodamine 6G) and a SERS substrate for real-time monitoring of the degradation quantitatively.
    Chemical Communications 03/2013; · 6.38 Impact Factor

Publication Stats

1k Citations
378.38 Total Impact Points

Institutions

  • 2008–2014
    • Soochow University (PRC)
      • • Jiangsu Key Laboratory for Carbon-based Functional Materials and Devices
      • • Functional Nano & Soft Materials Laboratory
      Wu-hsien, Jiangsu Sheng, China
  • 2004–2013
    • Anhui Normal University
      Wu-hu-shih, Anhui Sheng, China