Hui Zhang
Zhejiang University
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Publication
Featured researches published by Hui Zhang.
Inorganic Chemistry | 2011
Ning Du; Yanfang Xu; Hui Zhang; Jingxue Yu; Chuanxin Zhai; Deren Yang
A simple microemulsion-based method has been developed to synthesize ZnCo(2)(C(2)O(4))(3) nanowires that can be transformed to porous ZnCo(2)O(4) nanowires under annealing conditions. The morphology of porous ZnCo(2)O(4) nanowires can be tuned by the initial ZnCo(2)(C(2)O(4))(3) nanowires and the annealing temperatures. The as-synthesized porous ZnCo(2)O(4) nanowires have been applied as anode materials of Li-ion batteries, which show superior capacity and cycling performance. The porous one-dimensional (1D) nanostructures and large surface area are responsible for the superior performance. Moreover, it is indicated that porous ZnCo(2)O(4) nanowires synthesized at low annealing temperature (500 °C) show larger capacity and better cycling performance than that prepared at high annealing temperature (700 °C), because of their higher porosity and larger surface area.
Nanotechnology | 2006
Hongliang Zhu; Deren Yang; Guixia Yu; Hui Zhang; Kuihong Yao
A simple hydrothermal process is proposed for synthesizing SnO2 quantum dots (QDs), in which hydrazine hydrate is used as the mineralizer instead of NaOH. X-ray diffraction, high-resolution transmission electron microscopy (HRTEM) and UV–vis diffuse reflectance spectroscopy (DRS) were employed to characterize the product. The HRTEM image shows that the diameters of the SnO2 nanoparticles fall into a small range of 2.3–3.1 nm, with the majority being less than the exciton Bohr radius of SnO2 (~2.7 nm). Analysis of the DRS spectrum showed the band gap of the SnO2 QDs to be 3.88 eV, exhibiting a 0.28 eV blue shift from that of the bulk SnO2 (3.6 eV). The mechanism for hydrothermal synthesis of the SnO2 QDs using hydrazine hydrate as the mineralizer is discussed.
Nanotechnology | 2004
Shenzhong Li; Hui Zhang; Yujie Ji; Deren Yang
CuO nanodendrites have been synthesized by a simple and novel hydrothermal method. Their morphology, structure, and composition have been also characterized. The results show that an as-prepared nanodendrite is composed of a main branch-like nanorod near upon a micrometre in length and about 100 nm in diameter and the sub-branch nanorods several hundred nanometres in length and 20–60 nm in diameter. The dendrite-like CuO nanostructures are of monoclinic phase and single crystalline in nature. The investigation of the hydrothermal process assisted by different quantities of ethylene glycol (EG) indicates that EG plays a critical role in the formation of dendrite-like CuO nanostructures. A possible mechanism for the formation of such CuO nanostructures is discussed. Furthermore, the correlation between the optical spectrum and the different morphologies of copper oxides nanomaterials is also discussed.
Journal of Materials Chemistry | 2012
Jiazheng Wang; Ning Du; Hui Zhang; Jingxue Yu; Deren Yang
We demonstrate the synthesis of three-dimensional Cu–Ge core–shell nanowire array electrodes by directly depositing Ge on the surface of pre-synthesized Cu nanowire arrays via an rf-sputtering method. When used as anodes of lithium-ion batteries, the Cu–Ge nanowire arrays display a high capacity of 1419 mAh g−1 at 0.5 C after 40 cycles and 734 mAh g−1 at 60 C after 80 cycles, which is better than planar electrodes. The improved performance can be attributed to the good electrical contact, fast electron transport and good strain accommodation of the nanowire array electrodes. The effect of the thickness of Ge layer on the electrochemical performance of the three-dimensional electrodes has also been investigated.
Nano Letters | 2015
Ting Bian; Hui Zhang; Yingying Jiang; Chuanhong Jin; Jianbo Wu; Hong Yang; Deren Yang
Pt epitaxial layer on a nanoparticle with twinned structure and well-defined shape is highly desirable in order to achieve high performance in both catalytic activity and durability toward oxygen reduction reaction (ORR). However, it remains tremendously challenging to produce conformal, heterogeneous, twinned nanostructures due to the high internal strain and surface energy of Pt. In addition, these twinned nanostructures may be subject to degradation in highly corrosive ORR environments due to the high energy of twin boundary. Here we report the synthesis of Au-Pt core-shell star-shaped decahedra bounded mainly by {111} facets, in which Pt shells with controlled thickness epitaxially grew on Au cores with a 5-fold twinned structure. The incorporation of the amine group decreases the surface energy of Pt by strong adsorption and thus facilitates the epitaxial growth of Pt on Au core instead of the dendritic growth. In addition, Br(-) ion could largely stabilize the {111} facets of Pt, which prevent the formation of spherical nanoparticles. The Au-Pt core-shell decahedra with thicker Pt shell exhibited enhanced ORR properties in terms of activity and durability. Specifically, AuPt1.03 star-shaped decahedra achieved the highest mass activity (0.94 mA/μg(Pt)) and area activity (1.09 mA/cm(2)(Pt)), which is ∼6.7 and 5 times, respectively, as high as those of the commercial Pt/C (ETEK). Significantly, such star-shaped decahedra were highly stable with ∼10% loss in area activity and ∼20% loss in mass activity after 30,000 CV cycles in O2 saturated acid solution.
Nanoscale Research Letters | 2010
Ning Du; Yanfang Xu; Hui Zhang; Chuanxin Zhai; Deren Yang
Hematite (α-Fe2O3) and magnetite (Fe3O4) nanowires with the diameter of about 100 nm and the length of tens of micrometers have been selectively synthesized by a microemulsion-based method in combination of the calcinations under different atmosphere. The effects of the precursors, annealing temperature, and atmosphere on the morphology and the structure of the products have been investigated. Moreover, Co3O4 nanowires have been fabricated to confirm the versatility of the method for metal oxide nanowires.
Nanotechnology | 2003
Hui Zhang; Yujie Ji; Xiangyang Ma; Jin Xu; Deren Yang
Long Bi2S3 nanowires have been prepared via the thioglyolic acid (HSCH2COOH, TGA) assisted hydrothermal method. The x-ray diffraction pattern shows that the Bi2S3 nanowires obtained are of orthorhombic phase. High resolution transmission electron microscopy identifies that the Bi2S3 nanowires are single crystalline in nature. Furthermore, we give a preliminary presentation of the mechanism for the TGA-assisted hydrothermal synthesis of Bi2S3 nanowires.
Journal of Physical Chemistry B | 2008
Ning Du; Hui Zhang; Juner Chen; Jingyu Sun; Bingdi Chen; Deren Yang
A novel layer-by-layer approach has been developed to synthesize polycrystalline SnO(2) hollow spheres with tunable shell thickness and size using SiO(2) spheres as a template. The surface of the SiO(2) spheres has been first modified by the polyelectrolyte, and subsequently, the compact SnO(2) layer has deposited on the surface of the SiO(2) spheres through a redox reaction because of the electrostatic attraction between the charged species. After HF etching treatment, the uniform SnO(2) hollow spheres have been obtained. The approach presented herein has been extended to synthesize other metal oxide and sulfide hollow spheres such as In(2)O(3) and ZnS. Moreover, the as-synthesized SnO(2) hollow spheres have been applied in lithium-ion battery and show improved performance compared with SnO(2) nanoparticles. The high surface area and stable hollow structure of the SnO(2) hollow spheres may be responsible for the improved performance.
Optics Express | 2009
Xiangyang Ma; Jingwei Pan; Peiliang Chen; Dongsheng Li; Hui Zhang; Yang Yang; Deren Yang
We report the electrically pumped ultraviolet random lasing from ZnO nanorod arrays on Si. Metal-insulator-semiconductor structures in a form of Au/SiO(2)/ZnO-nanorod-array were fabricated on Si. Such devices exhibit random lasing when the Au electrode is applied with a sufficiently high positive voltage. In this context, in the region adjacent to SiO(2)/ZnO-nanorod-array interface, stimulated emission from ZnO occurs due to population inversion and, moreover, light is scattered by the nanorods and SiO(2) films. Therefore, random lasing proceeds due to optical gain achieved by the stimulated emission and multiple scattering.
Chemical Communications | 2008
Ning Du; Hui Zhang; Xiangyang Ma; Deren Yang
CNT/Au/SnO(2) nanotubes have been synthesized through homogeneous coating of Au and SnO(2) nanocrystals on carbon nanotubes (CNTs) and applied in a room-temperature CO gas sensor.