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Showing papers by "Harbin Engineering University published in 2011"


Journal ArticleDOI
TL;DR: An asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte as mentioned in this paper.
Abstract: Asymmetric supercapacitor with high energy density has been developed successfully using graphene/MnO2 composite as positive electrode and activated carbon nanofibers (ACN) as negative electrode in a neutral aqueous Na2SO4 electrolyte. Due to the high capacitances and excellent rate performances of graphene/MnO2 and ACN, as well as the synergistic effects of the two electrodes, such asymmetric cell exhibits superior electrochemical performances. An optimized asymmetric supercapacitor can be cycled reversibly in the voltage range of 0–1.8 V, and exhibits maximum energy density of 51.1 Wh kg−1, which is much higher than that of MnO2//DWNT cell (29.1 Wh kg−1). Additionally, graphene/MnO2//ACN asymmetric supercapacitor exhibits excellent cycling durability, with 97% specific capacitance retained even after 1000 cycles. These encouraging results show great potential in developing energy storage devices with high energy and power densities for practical applications.

1,768 citations


Journal ArticleDOI
25 Jan 2011-ACS Nano
TL;DR: This work demonstrates a green and facile approach to the synthesis of graphene nanosheets based on Fe reduction of exfoliated graphite oxide, resulting in a substantial removal of oxygen functionalities of thegraphite oxide.
Abstract: The synthesis of graphene nanosheets from graphite oxide typically involves harmful chemical reductants that are undesirable for most practical applications of graphene. Here, we demonstrate a green and facile approach to the synthesis of graphene nanosheets based on Fe reduction of exfoliated graphite oxide, resulting in a substantial removal of oxygen functionalities of the graphite oxide. More interestingly, the resulting graphene nanosheets with residual Fe show a high adsorption capacity of 111.62 mg/g for methylene blue at room temperature, as well as easy magnetic separation from the solution. This approach offers a potential for cost-effective, environmentally friendly, and large-scale production of graphene nanosheets.

821 citations


Journal ArticleDOI
TL;DR: In this article, a hybrid chemically converted graphene nanosheet/Ni2+/Al3+ layered double-hydroxide (GNS/LDH) composite for supercapacitor material has been fabricated by a hydrothermal method.
Abstract: A hybrid chemically converted graphene nanosheet/Ni2+/Al3+ layered double-hydroxide (GNS/LDH) composite for supercapacitor material has been fabricated by a hydrothermal method. Scanning electron microscopy and transmission electron microscopy results reveal that Ni2+/Al3+ LDH platelets homogeneously grew onto the surfaces of the GNSs as spacers to keep the neighboring sheets separate. Electrochemical properties were characterized by cyclic voltammetry, galvanostatic charge/discharge measurements, and electrochemical impedance spectroscopy. The composite exhibits a maximum specific capacitance of 781.5 F/g and excellent cycle life with an increase of the specific capacitance of 38.07% after 50 cycle tests. Even after 200 cycle tests, the increase of the capacitance is 22.56% compared with the initial capacitance.

493 citations


Journal ArticleDOI
TL;DR: Graphene that had nanomeshes, only one to two graphene layers, and specific surface areas of up to 1654 m(2) g(-1) was produced on gram-scale by template growth on porous MgO layers, which gave excellent electrochemical capacitance, cycle stability and rate performance.

353 citations


Journal ArticleDOI
TL;DR: The results show that the array of CuO nanosheets forms a uniform film of around 5 μm in thickness on nickel foam skeleton and exhibits a specific capacitance of 569 F g−1 at a current density of 5 mA cm−2 in 6.0 mol dm−3 KOH electrolyte.

337 citations


Journal ArticleDOI
08 Apr 2011-ACS Nano
TL;DR: The fabrication of 3D carbonaceous material composed of 1D carbon nanofibers grown on 2D graphene sheets via a CVD approach in a fluidized bed reactor shows high reversible capacity, high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes.
Abstract: We report on the fabrication of 3D carbonaceous material composed of 1D carbon nanofibers (CNF) grown on 2D graphene sheets (GNS) via a CVD approach in a fluidized bed reactor. Nanographene-constructed carbon nanofibers contain many cavities, open tips, and graphene platelets with edges exposed, providing more extra space for Li(+) storage. More interestingly, nanochannels consisting of graphene platelets arrange almost perpendicularly to the fiber axis, which is favorable for lithium ion diffusion from different orientations. In addition, 3D interconnected architectures facilitate the collection and transport of electrons during the cycling process. As a result, the CNF/GNS hybrid material shows high reversible capacity (667 mAh/g), high-rate performance, and cycling stability, which is superior to those of pure graphene, natural graphite, and carbon nanotubes. The simple CVD approach offers a new pathway for large-scale production of novel hybrid carbon materials for energy storage.

256 citations


Journal ArticleDOI
TL;DR: In this article, a green and facile approach was demonstrated to prepare graphene nanosheets/ZnO composites for supercapacitor materials, where small ZnO particles successfully anchored onto graphene sheets as spacers to keep the neighboring sheets separate.

247 citations


Journal ArticleDOI
TL;DR: In this paper, the effect of hot extrusion on the corrosion behavior of AZ91 magnesiun alloy was investigated by weight loss, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization measurements.

221 citations


Journal ArticleDOI
TL;DR: Graphene nanosheet/alumina composite has been prepared by spark plasma sintering as discussed by the authors, which is a homogeneous distribution of nanosheets in an alumina matrix could be obtained by the electrostatic attraction between graphite oxide and alumina particles and their subsequent reduction.

221 citations


Journal ArticleDOI
Bangan Lu1, Dianxue Cao1, Pan Wang1, Guiling Wang1, Yinyi Gao1 
TL;DR: In this paper, the effects of Ni content on the morphology, structure and catalytic performance for oxygen evolution reaction were investigated by scanning electron microscopy, X-ray diffraction spectroscopy and electrochemical techniques including cyclic voltammetry, chronopotentiometry and electrical impedance spectrography.

216 citations


Journal ArticleDOI
TL;DR: Drug (Fenbufen, FBF)-loaded poly(D,L-lactide-co-glycolide) (PLGA) and PLGA/gelatin nanofibrous scaffolds were fabricated via electrospinning technique and the release rate of FBF was found to be increased with the increment of gelatin content for all the composite samples.

Journal ArticleDOI
TL;DR: In this article, a type of graphene nanosheet/δ-MnO2 composite was synthesized by a microwave-assisted method, and the Ni (II) removal potential of GNS/Mn O2 from solution was investigated.

Journal ArticleDOI
TL;DR: Extraordinarily high reversible capacity of lithium-ion battery anodes is realized from SnO(2)/α-MoO(3) core-shell nanobelts that makes extra Li(2)O reversibly convert to Li(+).

Journal ArticleDOI
TL;DR: Ultrafast charging/discharging of lithium-ion battery anodes is realized from porous Co(3)O(4) nanoneedle arrays growing on copper foils, implying that nano-arrays growing directly on copperfoils are good candidates for anodes.

Journal ArticleDOI
TL;DR: In this paper, the up-conversion (UC) luminescent porous silica fibers decorated with NaYF(4):Yb(3+), Er(3+) nanocrystals (NCs) are prepared by the electrospinning process using cationic surfactant P123 as a template.
Abstract: Up-conversion (UC) luminescent porous silica fibers decorated with NaYF(4):Yb(3+), Er(3+) nanocrystals (NCs) (denoted as NaYF(4):Yb(3+), Er(3+)@silica fiber) are prepared by the electrospinning process using cationic surfactant P123 as a template. Monodisperse and hydrophobic oleic acid capped beta-NaYF(4): Yb(3+), Er(3+) NCs are prepared by thermal decomposition methodology. Then, these NCs are transferred into aqueous solution by employing cetyltrimethylammonium bromide (CTAB) as secondary surfactant. The water-dispersible beta-NaYF(4):Yb(3+), Er(3+) NCs are dispersed into precursor electrospinning solution containing P123 and tetraethyl orthosilicate (TEOS), followed by preparation of precursor fibers via electrospinning. Finally, porous alpha-NaYF(4):Yb(3+), Er(3+)@silica fiber nanocomposites are obtained after annealing the precursor fibers containing beta-NaYF(4):Yb(3+), Er(3+) at 550 degrees C. The as-prepared alpha-NaYF(4):Yb(3+), Er(3+)@silica fiber possesses porous structure and UC luminescence properties simultaneously. Furthermore, the obtained nanocomposites can be used as a drug delivery host carrier and drug storage/release properties are investigated, using ibuprofen (IBU) as a model drug. The results indicate that the IBU-loaded alpha-NaYF(4):Yb(3+), Er(3+)@silica fiber nanocomposites show UC emission of Er(3+) under 980 nm NIR laser excitation and a controlled release property for IBU. Meanwhile, the UC emission intensity of IBU-alpha-NaYF(4):Yb(3+), Er(3+)@silica fiber system varies with the released amount of IBU.

Journal ArticleDOI
TL;DR: In this paper, the corrosion behavior of extruded Nd-free AZ91 and extruded AZ91 + 1.5Nd alloy was investigated by weight loss and electrochemical measurements.

Journal ArticleDOI
TL;DR: The CM instrument has significant changes in the phase transformation behavior, compared with conventional superelastic NiTi instruments.

Journal ArticleDOI
TL;DR: The cytotoxicity evaluation revealed that Ti NiAg alloy extract induced slight toxicity to cells, but the viability of experimental cells was similar to or higher than that of TiNi alloy extract, and the corresponding antibacterial mechanism for the TiNiAg alloy is discussed.

Journal ArticleDOI
TL;DR: In this article, a new Mg-air battery based on Mg−14Li−1Al−0.1Ce was prepared and the battery performance was investigated by constant current discharge test.

Journal ArticleDOI
TL;DR: In this paper, the performance of epoxy coatings containing emeraldine base polyaniline (PANI) or hydrofluoric acid doped PANI on AZ91D magnesium alloy were studied by EIS and Pull-Off Adhesion Test.

Journal ArticleDOI
TL;DR: In this paper, the effects of dopant on the physical and electrochemical characteristics of Li2FeSiO4 were investigated, and the effect of Zn2+ doping on the lattice parameters was shown.

Journal ArticleDOI
TL;DR: Morphological characterization using scanning electron microscopy showed that the aligned nanofiber diameter distribution obtained by electrospinning of polymer blend increased with the increase of chitosan content which was similar to that of randomly oriented nanofibers.

Journal ArticleDOI
TL;DR: This paper presents an effective and practical method for finding safe passage for ships in possible collision situations, based on the potential field method, which is shown to be effective in automatic ship handling for ships involved in complex navigation situations.

Journal ArticleDOI
TL;DR: In this paper, a representative volume cell (RVC) is chosen to study the uniaxial compressive mechanical properties of the braided composites with different braid angles by combing damage theory and finite element method.

Journal ArticleDOI
TL;DR: In this paper, the effects of Ti and Mg codoping on the physical and electrochemical characteristics of Li3V2(PO4)3 were investigated by a sol-gel method.
Abstract: Ti and Mg codoped Li3V2–2xTixMgx(PO4)3 (x = 0, 0.05, 0.10, 0.20, and 0.25) samples were prepared by a sol–gel method. The effects of Ti and Mg codoping on the physical and electrochemical characteristics of Li3V2(PO4)3 were investigated. Compared with the XRD pattern of the undoped sample, those of the Ti and Mg codoped samples have no extra reflections, which indicates that Ti and Mg enter the structure of Li3V2(PO4)3. According to the results of charge–discharge measurements, the initial capacity of Li3V2–2xTixMgx(PO4)3 at a low current density (0.2 C) decreases with increasing x. However, the discharge capacities at higher current densities (1 and 2 C) and the cycling stability are improved by a low amount of Ti and Mg codoping (x = 0.05), and moreover, EIS measurements indicate the lower charge transfer resistance of Li3V1.9Ti0.05Mg0.05(PO4)3. The improved electrochemical performance of Li3V1.9Ti0.05Mg0.05(PO4)3 can be attributed to its higher structural stability and smaller particle size. When x is ...

Journal ArticleDOI
TL;DR: These Co(3)O(4) microspheres show much higher ethanol sensitivity and selectivity at a relatively low temperature (135 °C) compared with those of commercial Co( 3)O (4) nanoparticles.

Journal ArticleDOI
TL;DR: In this article, binary rare earth fluoride this article3 nano/microcrystals with multiform crystal structures (hexagonal and orthorhombic) and morphologies (nanodisks, secondary aggregates constructed from nanoparticles, and elongated nanoparticles) have been successfully fabricated.
Abstract: Via a fast, facile and environmentally-friendly microwave-assisted ionic liquid method, binary rare earth fluoride REF3 (RE = La–Lu, Y) nano/microcrystals with multiform crystal structures (hexagonal and orthorhombic) and morphologies (nanodisks, secondary aggregates constructed from nanoparticles, and elongated nanoparticles) have been successfully fabricated. The experimental results indicate that the use of microwave irradiation and ionic liquid [BIBM][BF4] are responsible for the products. Microwave irradiation accelerates dramatically the reaction rate and shortens the reaction time. [BIBM][BF4] plays multiple roles as solvent, reactant and template. The possible formation mechanisms for REF3 nano/microcrystals with diverse well-defined morphologies have been presented in detail. Additionally, we systematically investigate the magnetic and luminescent properties of the GdF3 : Ce3+/Ln3+ (Ln = Eu, Tb and Dy). They show paramagnetic property with mass magnetic susceptibility value of 1.10 × 10−4 emu g−1 Oe at 300 K, and red (Eu3+), green (Tb3+) and blue (Dy3+) emissions due to the Ce3+ → Ln3+ (Ln = Tb, Eu, and Dy) energy transfer. This energy transfer occurs through the energy migration process like Ce3+ → Gd3+→ (Gd3+)n → Ln3+ and the Gd3+ ions plays an intermediate role in the process.

Journal ArticleDOI
TL;DR: In this paper, the authors used the change of the heterojunction barrier formed at the interface between CeO 2 and TiO 2 to explain the enhanced ethanol sensing properties of crystal core/shell nanorods.
Abstract: Crystalline CeO 2 /TiO 2 core/shell nanorods were fabricated by a hydrothermal method and a subsequent annealing process under the hydrogen and air atmosphere. The thickness of the outer shell composed of crystal TiO 2 nanoparticles can be tuned in the range of 5–11 nm. The crystal core/shell nanorods exhibited enhanced gas-sensing properties to ethanol vapor in terms of sensor response and selectivity. The calculated sensor response based on the change of the heterojunction barrier formed at the interface between CeO 2 and TiO 2 is agreed with the experimental results, and thus the change of the heterojunction barrier at different gas atmosphere can be used to explain the enhanced ethanol sensing properties.

Journal ArticleDOI
TL;DR: In this paper, the microstructures, mechanical properties and corrosion behavior of Mg-4Al-xCe-0.3Mn alloys were investigated and the cross-section of test bar was divided into the fine skin region and relatively coarse interior region by a narrow band.

Journal ArticleDOI
TL;DR: In this paper, multicolor and monodisperse Gd2O3:Ln (Ln = Eu3+, Tb3+, Dy3+, and Sm3+) nanocrystals with narrow size distribution were prepared by a homogeneous precipitation method followed by a subsequent calcination process.
Abstract: Multicolor and monodisperse Gd2O3:Ln (Ln = Eu3+, Tb3+, Dy3+, Sm3+, Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) nanocrystals (NCs) with narrow size distribution were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transformed infrared (FT-IR), thermogravimetric and differential thermal analysis (TG-DTA), photoluminescence (PL) spectra, cathodoluminescence (CL) spectra, and kinetic decays were employed to characterize the samples. The results show that the Gd2O3:Ln NCs can be directly indexed to cubic Gd2O3 phase with high purity. And the possible formation mechanism and the chemical reaction of each step to form spherical Gd2O3:Ln NCs are proposed according to the concerned analysis. Upon ultraviolet and low-voltage electron beams excitation, Gd2O3:Ln (Ln = Eu3+, Tb3+, Dy3+, and Sm3+) NCs exhibit respective bright red (Eu3+, 5D0 → 7F2), green (Tb3+, 5D4 → 7F5), blue (Dy3+, 4F9/2 → 6H13/2) and yellow (Sm3+, 4G5/2 → 6H7/2) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Gd2O3:Ln (Ln = Yb3+/Er3+, Yb3+/Tm3+, and Yb3+/Ho3+) exhibit characteristic up-conversion (UC) emissions of Er3+, Tm3+, and Ho3+, respectively.