Chaoying Ni

University of Delaware, Ньюарк, Delaware, United States

Are you Chaoying Ni?

Claim your profile

Publications (91)312.8 Total impact

  • Xiazhang Li · Wei Zhu · Yu Yin · Xiaowang Lu · Chao Yao · Chaoying Ni
    [Show abstract] [Hide abstract]
    ABSTRACT: La1−xAgxFeO3/halloysites nanotubes (HNTs) nanocomposite was synthesized by sol–gel method. It was characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectroscopy and UV–visible diffused reflectance spectroscopy measurements. The photo-activity of the La1−xAgxFeO3/HNTs nanocomposite was evaluated via degradation of methylene blue (MB) under visible-light irradiation. The results showed that the HNTs with unique pore structure favored the adsorption of organic molecules. Adequate Ag+ doping improved the absorption ability for visible light. The La0.95Ag0.05FeO3/HNTs demonstrated the best photocatalytic performance, which achieved as high as 99 % for MB degradation exposed 2 h irradiation. However,further increasing of Ag+ doping gradually reduced the photocatalytic activity. The nanocomposite catalyst showed outstanding recyclability after eight cycles which still remained up to 90 %.
    No preview · Article · Jan 2016 · Journal of Materials Science Materials in Electronics
  • [Show abstract] [Hide abstract]
    ABSTRACT: Novel attapulgite(ATP)-CeO2/MoS2 ternary nanocomposites were synthesized by microwave assisted assembly method. The structures of the nanocomposites were characterized by XRD, FT-IR, UV–vis, XPS and in situ TEM. The photocatalytic activities of ATP-CeO2/MoS2 composites were investigated by degradating dibenzothiophene (DBT) in gasoline under visible light irradiation. The effect of the mass ratio of CeO2 to MoS2 on photocatalytic activity was investigated. The results indicate that the three-dimensional network structure is firmly constructed by ATP skeleton, CeO2 particles and MoS2 nanosheet which effectively increase the surface area of the composites and promote the separation of electrons and holes by resulting electronic transmission channels of multi-channel in space. The degradation rate of DBT can reach 95% under 3 h irradiation when the mass ratio of CeO2/MoS2 is 4/10. A plausible mechanism for the photocatalytic oxidative desulfurization of this nanocomposite is put forward.
    No preview · Article · Dec 2015 · Applied Surface Science
  • [Show abstract] [Hide abstract]
    ABSTRACT: Novel palygorskite (PG) supported Ce1−xLaxO2−δ nanocomposites were prepared by a facile in situ deposition method using hexamethylenetetramine as the precipitant. The textural and structural properties of the products were characterized by XRD, HRTEM, FT-IR, Raman, XPS and TPR techniques. The results indicated that the oxide particles with an average size of about 5 nm were loaded successfully onto the surface of PG rods and were uniformly dispersed. The catalytic activities of Ce1−xLaxO2−δ/PG (x from 0.1 to 0.9) for CO oxidation were investigated. La3+ doping was found to have critical effects on the CO oxidation activity. The best Ce1−xLaxO2−δ/PG nanocomposite was obtained when the x value was adjusted to 0.5, and the reaction rate was found to be three times higher than that of a commercial CeO2 catalyst. Adequate introduction of La3+ promotes the formation of non-stoichiometric Ce1−xLaxO2−δ and is responsible for the formation of oxygen vacancies and surface superoxide ions. However, when the doping ratio increases to 0.6 or higher, co-precipitation of La2O3 leads to decreased redox properties and CO oxidation activity.
    No preview · Article · Sep 2015 · Catalysis Science & Technology
  • Xiazhang Li · Chao Yao · Xiaowang Lu · Yu Yin · Shixiang Zuo · Chaoying Ni
    [Show abstract] [Hide abstract]
    ABSTRACT: TiO2/attapulgite (ATP) nanocomposites were synthesized by a low temperature hydrolysis method, and were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FT-IR) spectroscopy. Results indicate that the weight ratio of TiO2 to ATP has critical effect on the crystalline structure of TiO2. Weight ratios of MTiO2/MATP at 0.25:1, 0.5:1 and 1:1 result in anatase TiO2, while MTiO2/MATP at 2:1 leads to the rutile phase. Anatase-rutile mixed TiO2 can be obtained at MTiO2/MATP = 1.5:1, and the mixed phase composite demonstrates the highest photocatalytic activity for the degradation of methyl orange with a 99% conversion within 40 min under UV light irradiation. The enhanced separation of photogenerated electron–hole pairs in mixed rutile-anatase is believed responsible for the improvement of photocatalytic activity.
    No preview · Article · Jul 2015 · Science of Advanced Materials
  • [Show abstract] [Hide abstract]
    ABSTRACT: Pulsed laser deposition technique has been used to manipulate the structural order of Fe67Co33 films grown at various substrate temperatures. Films deposited at room temperature exhibited two phases including the stable crystalline phase embedded in the amorphous phase. The crystalline phase separated into two distinct bcc phases as evident from the splitting of (110) reflections, as compared to the bulk counterpart which crystalize into the single phase bcc structure. Both crystalline phases and the amorphous phase were metastable. Films prepared at higher substrate temperatures (∼500oC), crystallized into the single stable equilibrium bcc structure. Orientation dependent magnetic properties are also presented for the films prepared at both room temperature and higher substrate temperatures. As expected, the easy axes lie parallel to the plane of the substrate due to shape anisotropy. Out of plane magnetization for the films which exhibited short range ordering is found to saturate at smaller field compared to films where single phase bcc structure is stabilized.
    No preview · Article · Mar 2015 · Current Applied Physics
  • Source

    Full-text · Dataset · Mar 2015
  • Liangdong Feng · Yufu Zhu · Hongyan Ding · Chaoying Ni
    [Show abstract] [Hide abstract]
    ABSTRACT: Nickel based materials have been intensively investigated and considered as good potential electrode materials for pseudocapacitors due to their high theoretical specific capacity values, high chemical and thermal stability, ready availability, environmentally benign nature and lower cost. This review firstly examines recent progress in nickel oxides or nickel hydroxides for high performance pseudocapacitor electrodes. The advances of hybrid electrodes are then assessed to include hybrid systems of nickel based materials with compounds such as carbonaceous materials, metal and transition metal oxides or hydroxides, in which various strategies have been adopted to improve the electrical conductivity of nickel oxides or hydroxides. Furthermore, the energy density and power density of some recently reported NiO, nickel based composites and NiCo2O4 are summarized and discussed. Finally, we provide some perspectives as to the future directions of this intriguing field.
    No preview · Article · Dec 2014 · Journal of Power Sources
  • Xiazhang Li · Chao Yao · Xiaowang Lu · Zonglin Hu · Yu Yin · Chaoying Ni
    [Show abstract] [Hide abstract]
    ABSTRACT: Halloysite nanotube supported hybrid CeO2–AgBr nanocomposite was synthesized by a facile microwave mediated method. The molar ratio of CeO2 and AgBr in the halloysite–CeO2–AgBr nanocomposite was adjusted so that r = nAg/(nAg + nCe) was selected as 0.0, 0.25, 0.33, 0.40, 0.45, and 0.50 respectively. X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and UV–Visible diffused reflectance spectroscopy (UV–Vis) were employed to investigate the structure and optical properties of the nanocomposites. Results indicate that among the pure halloysite and CeO2–AgBr loaded halloysite nanocomposites, the molar fraction r has a critical effect on the photocatalytic activity, which increases as the AgBr content increases to r ≤ 0.4 and decreases when r > 0.4. The highest conversion of methyl orange reached 99% within 80 min by using halloysite–CeO2–AgBr at r = 0.4, which was much higher than pure halloysite and CeO2–AgBr. As an exploratory study, the introduction of AgBr species was found to extend the spectral response from UV to visible region and improve the separation of electron–hole pairs. The repeatable use of the nanocomposite photocatalyst with little depreciation was also confirmed.
    No preview · Article · Nov 2014 · Applied Clay Science
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Protective hard coatings on steel that are produced by electrospark deposition (ESD) methods that do not require vacuum conditions are compared, and the interfaces formed are interrogated by a combination of analytical methods. A titanium carbonitride (TiCN) coating is produced and compared to a tungsten carbide (WC) ESD coating. Following deposition onto a 4140 grade steel substrate, the coatings were compared by X-ray photoelectron spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, transmission electron microscopy, atomic force microscopy, X-ray diffraction, and nanoindentation test to determine Young's modulus as an indicator of mechanical strength. It was found that the coatings produced void- and impurity-free interfaces but that the interfaces are drastically different for the two coatings investigated and some of the differences can be explained based on the different melting points of the two materials that affect the process of ESD.
    Full-text · Article · Nov 2014 · Surface and Coatings Technology
  • Source
    Yufu Zhu · Fei Deng · Chaoying Ni · Wenzhong Shen
    [Show abstract] [Hide abstract]
    ABSTRACT: Novel ZnO core/shell nanostructures were constructed by depositing a porous ZnO layer directly on the surfaces of pre-fabricated ZnO nanowires through a facile chemical method. The morphology and structure of the obtained products have been investigated by field-emission scanning electron microscopy, high-resolution transmission electron microscopy and X-ray diffraction analysis. In these unique nanostructures, the porous overlayer exhibits a large surface area for sufficient dye loading to enhance light harvesting and the ZnO nanowire cores provide direct conduction pathways for the photogenerated electron transport to diminish the chance of electron recombination. The obtained ZnO nanostructures were used as photoanode material in dye-sensitized solar cell which showed an increase in performance of 141 % compared with an equivalent solar cell employing ZnO nanowire arrays as photoanode. This result was achieved mainly due to an increase in photogenerated current density directly resulting from improved light harvesting of the porous layer.
    Full-text · Article · Oct 2014 · Journal of Materials Science Materials in Electronics
  • [Show abstract] [Hide abstract]
    ABSTRACT: We fabricated and characterized chalcogenide glass on CaF2 resonators with a record intrinsic quality factor of 6 × 105, and applied these devices to demonstrate cavity enhanced chemical sensing near 5.2 μm wavelength.
    No preview · Article · Sep 2014
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A simple synthesis route was designed to fabricate a novel hierarchical nanostructure consisting of a zinc hydroxide fluoride [Zn(OH) F] nanorod core with a shell of porous wrinkle textured zinc carbonate hydroxide [Zn-5(CO3)(2)(OH)(6)]. By adding two precipitating agents, ammonium fluoride (NH4F) and urea [(NH2)(2)CO], the one-pot reactions realized sequential decomposition of the precipitating agents following a temperature ramp and the onset of a conformal shell of Zn-5(CO3)(2)(OH)(6) to succeed the formation of a preferentially oriented Zn(OH) F nanorod forest. Single phase Zn(OH) F nanorods and Zn-5(CO3)(2)(OH)(6) microspheres were also obtained in the absence of one of the precipitating agents. These two precursors in three configurations were transformed by calcination to porous ZnO nanostructures with the original morphologies and pore structures retained. Chemical reactions and the formation mechanisms are proposed and discussed for both of the precursors and the resulting products from the calcination. The ZnO nanostructures were successfully employed in dye-sensitized solar cells. The light-to-electricity conversion shows that the hierarchical ZnO transformed from core/shell structured Zn(OH)F/Zn-5(CO3)(2)(OH)(6) exhibits significant enhancement to the short-circuit current density due to its large specific surface area and high growth density compared with the nanorod and microsphere counterparts, respectively.
    Full-text · Article · Sep 2014 · Journal of Alloys and Compounds
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Nanoscale blending of electron-donor and electron-acceptor materials in solution-processed bulk heterojunction (BHJ) organic photovoltaic (OPV) devices is crucial for achieving high power conversion efficiency (PCE). We used a classic blend of P3HT:PCBM as a model to observe the nanoscale morphology of the P3HT fibrils and PCBM nanoclusters in the mixture. Energy-filtered transmission electron microscopy (EFTEM) clearly revealed a nanoscopic phase separation. Randomly connected and/or non-connected P3HT fibrous networks and PCBM domains, revealed by 2-dimensional (2D) micrographs, were observed by collecting electron energy loss spectra in the range of 19 eV and 30 eV. From EFTEM images, the average length and the diameter of P3HT fibrils were found to be approximately 70±5 nm and 15±2 nm, respectively. Combining the EFTEM, selected area electron diffraction (SAED) and X-ray diffraction (XRD) results, we were able to determine the number and spacing of the ordered chains in P3HT fibrils. There were 18+3 repeating units of P3HT perpendicular to the fibril, ∽184 layers of pi-pi stacking along the fibril and ∼9 layers of interchain stacking within the fibril. These conclusive observations provide an insight into the number of molecules found in one instance of ordered-plane stacking. This information is useful for the calculation of charge transport in semicrystalline polymers. Using crosssection samples prepared with a focused ion beam (FIB) technique, the vertical morphology of each phase was analyzed. By collecting 30 eV energy loss images, the phase separation in P3HT:PCBM system was distinguishable. A higher P3HT concentration was observed at the top of the cell, near Al contact, which could possibly cause loss of carriers and recombination due to a mismatch in the P3HT and Al energy bands.
    Full-text · Article · Jul 2014 · ACS Applied Materials & Interfaces
  • [Show abstract] [Hide abstract]
    ABSTRACT: Attapulgite/polypyrrole composites (ATP/PPys) with morphology difference were synthesized in water–ethanol mixture via modulating the surface property of ATP to expound the relationship of morphology and electrica property. The surface property of ATP shows important impacts on the modulated morphology of ATP/PPys, and their morphologies are closely related with the inherent property. The results indicate that the pristine ATP is beneficial to generate the rod-film composites, and the rod-film ATP/PPys have preferable electrical conductivity and specific capacitance compared with the rod–sphere ones.
    No preview · Article · Jul 2014 · Materials Letters
  • [Show abstract] [Hide abstract]
    ABSTRACT: The FePt alloy in the high magnetic anisotropy L10 phase is one of the most promising magnetic materials in many applications, including ultra-high-density magnetorecording. A new green chemical approach to synthesize magnetically hard L10 FePt nanoparticles is described in this paper by using crystalline saline complex hexaaquairon(II)hexachloroplatinate, [Fe(H2O)6]PtCl6, as the precursor. The crystal structure of this complex shows alternate layers of Fe and Pt atoms. After ball milling, annealing at 400 °C under a reducing atmosphere leads to the direct formation of FePt nanoparticles in the highly ordered L10 phase. This method is a green synthesis due to the low temperature for phase transformation, and the absence of organic solvents or surfactants in the reaction. Indeed the milling step is performed using NaCl as media, which can be easily removed with water. By varying the precursor/NaCl ratio, particles with size in the range of 6.2–13.2 nm were obtained. With the decrease of particle size, the room temperature coercivity of FePt nanoparticles also decreased from 10.9 kOe to 4.7 kOe.
    No preview · Article · Mar 2014 · Green Chemistry
  • [Show abstract] [Hide abstract]
    ABSTRACT: Chalcogenide glasses, namely the amorphous compounds containing sulfur, selenium, and/or tellurium, have emerged as a promising material candidate for mid-infrared integrated photonics given their wide optical transparency window, high linear and nonlinear indices, as well as their capacity for monolithic integration on a wide array of substrates. Exploiting these unique features of the material, we demonstrated high-index-contrast, waveguide-coupled As2Se3 chalcogenide glass resonators monolithically integrated on silicon with a high intrinsic quality factor of 2 × 105 at 5.2 micron wavelength, and what we believe to be the first waveguide photonic crystal cavity operating in the mid-infrared.
    No preview · Article · Feb 2014 · Proceedings of SPIE - The International Society for Optical Engineering
  • [Show abstract] [Hide abstract]
    ABSTRACT: We report the design of two collagen-mimetic peptide sequences, NSI and NSII, that self-assemble into structurally defined nano-scale sheets. The underlying structure of these nanosheets can be understood in terms of the layered packing of collagen triple helices in two dimensions. These nanosheet assemblies represent a novel morphology for collagen-based materials, which, on the basis of their defined structure, may be envisioned as potentially biocompatible platforms for controlled presentation of chemical functionality at the nano-scale. The molecularly programmed self-assembly of peptides NSI and NSII into nanosheets suggests that sequence-specific macromolecules offer significant promise as design elements for two-dimensional (2D) assemblies. This investigation provides a design rubric for fabrication of structurally defined, peptide-based nanosheets using the principles of solu-tion-based self-assembly facilitated through complementary electrostatic interactions.
    No preview · Article · Feb 2014 · Journal of the American Chemical Society
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Thin film processing methods offer a number of means to investigate and engineer ion conduction in solid electrolytes. In this work, we present fabrication and characterization of Y-doped CeO2 thin films where the Y-dopants were distributed homogeneously or were condensed into increasingly concentrated layers, to the limit of alternating layers of pure Y2O3 and pure CeO2. Both the entire film thickness and net Y-concentration were kept constant such that only the spatial distribution of dopants was altered. Space charge regions formed at interfaces between regions with varying vacancy concentrations, yielding vacancies trapped within two-dimensionally arranged accumulation regions. A Gouy–Chapman model was implemented in order to further investigate the distribution of the accumulated oxygen vacancies in the space charge regions of pure CeO2 layers. Comparison of the measured activation energy of conduction indicates that in films with intermediate dopant condensation, conduction occurred predominantly by vacancies trapped in the Y-containing layers. Conversely, in the film composed of alternating layers of Y2O3 and CeO2, vacancies trapped in the CeO2 space charge regions became significantly conductive, thus providing a means to determine the properties of vacancies in ceria that are trapped near dopants.
    Full-text · Article · Feb 2014 · Solid State Ionics
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In this article, we review our recent work on mid-infrared (mid-IR) photonic materials and devices fabricated on silicon for on-chip sensing applications. Pedestal waveguides based on silicon are demonstrated as broadband mid-IR sensors. Our low-loss mid-IR directional couplers demonstrated in SiNx waveguides are useful in differential sensing applications. Photonic crystal cavities and microdisk resonators based on chalcogenide glasses for high sensitivity are also demonstrated as effective mid-IR sensors. Polymer-based functionalization layers, to enhance the sensitivity and selectivity of our sensor devices, are also presented. We discuss the design of mid-IR chalcogenide waveguides integrated with polycrystalline PbTe detectors on a monolithic silicon platform for optical sensing, wherein the use of a low-index spacer layer enables the evanescent coupling of mid-IR light from the waveguides to the detector. Finally, we show the successful fabrication processing of our first prototype mid-IR waveguide-integrated detectors.
    Full-text · Article · Jan 2014 · Science and Technology of Advanced Materials
  • [Show abstract] [Hide abstract]
    ABSTRACT: Spin-orbit interaction-driven phenomena such as the spin Hall and Rashba effect in ferromagnetic/heavy metal bilayers enables efficient manipulation of the magnetization via electric current. However, the underlying mechanism for the spin-orbit interaction-driven phenomena remains unsettled. Here we develop a sensitive spin-orbit torque magnetometer based on the magneto-optic Kerr effect that measures the spin-orbit torque vectors for cobalt iron boron/platinum bilayers over a wide thickness range. We observe that the Slonczewski-like torque inversely scales with the ferromagnet thickness, and the field-like torque has a threshold effect that appears only when the ferromagnetic layer is thinner than 1 nm. Through a thickness-dependence study with an additional copper insertion layer at the interface, we conclude that the dominant mechanism for the spin-orbit interaction-driven phenomena in this system is the spin Hall effect. However, there is also a distinct interface contribution, which may be because of the Rashba effect.
    No preview · Article · Jan 2014 · Nature Communications

Publication Stats

2k Citations
312.80 Total Impact Points

Institutions

  • 2002-2015
    • University of Delaware
      • Department of Materials Science and Engineering
      Ньюарк, Delaware, United States
  • 2006
    • Drexel University
      • Department of Materials Science and Engineering
      Filadelfia, Pennsylvania, United States