Caiyun Nan

Solvothermal synthesis of lithium iron phosphate nanoplates

Uniform lithium iron phosphate nanoplates with a thickness of 30 nm, width of 100 nm, and length of 200 nm are synthesized by a solvothermal method. Electrochemical measurements show that the nanoplates exhibit low polarization and reach a discharge capacity of 165 mAh g−1 at 0.1 C, 140 mAh g−1 at 5 C.

Mesoporous Multicomponent Nanocomposite Colloidal Spheres: Ideal High‐Temperature Stable Model Catalysts

Insupported noble-metal catalysts the metal particles tend toaggregate during the reaction process, and the particle sizethus becomes larger which leads to lower catalytic activity.Additionally, the metal particles usually detach from thesupport when the corresponding catalyst is rubbed recipro-cally, which results in a sharp decrease of the active sites.Therefore, the design of an ideal nanostructure for supportednoble-metal catalysts that can overcome the above-men-tioned limits and, thus, display high stability, is a greatchallenge in this field.

Size and shape control of LiFePO4 nanocrystals for better lithium ion battery cathode materials

AbstractLithium iron phosphate (LiFePO4) is a potential high efficiency cathode material for lithium ion batteries, but the low electronic conductivity and single diffusion channel for lithium ions require good particle size and shape control during the synthesis of this material. In this paper, six LiFePO4 nanocrystals with different size and shape have been successfully synthesized in ethylene glycol. The addition sequence Fe-PO4-Li helps to form LiFePO4 nanocrystals with mostly {010} faces exposed, and increasing the amount of LiOH leads to a decrease in particle size. The electrochemical performance of the six distinct LiFePO4 particles show that the most promising LiFePO4 nanocrystals either have predominant {010} face exposure or high specific area, with little iron(II) oxidation.

Flexible SnS nanobelts： Facile synthesis, formation mechanism and application in Li-ion batteries

Abstract[020]-oriented tin sulfide nanobelts with a length/thickness ratio of 100 have been synthesized by a facile hydrothermal method without any surfactants, and the nanobelts have shown good strain-accommodating properties as well as good electrochemical performance as the anode for Li-ion batteries. The formation of the nanobelts results from a precipitation-dissolution-transformation mechanism, and the [020] oriented growth can be ascribed to the {010} facet family having the lowest atomic density. In particular, SnS shows clear Li-Sn alloying/de-alloying reversible reactions in the potential range 0.1–1.0 V. Based on galvanostatic measurements and electrochemical impedance spectroscopy, SnS nanobelts have shown impressive rate performance. The post-cycled SnS nanobelts were completely transformed into metallic tin, and preserved the one-dimensional structure due to their flexibility which accommodates the large volumetric expansion.

Selective Synthesis of Cu2O Nanocrystals as Shape‐Dependent Catalysts for Oxidative Arylation of Phenylacetylene

Shape-dependent nanocatalysis: Monodisperse cubic, rhombic dodecahedral, and octadecahedral Cu(2) O nanocrystals (NCs) were selectively synthesized. Cu(2) O octadecahedra exhibited the best activity upon recycling, though etched on nanoframes, in the ligand-free oxidative arylation of phenylacetylene. Rhombic dodecahedra had moderate activity and optimal stability, whereas cubes suffered significant loss of activity during recycling.

High-energy-density dielectric films based on polyvinylidene fluoride and aromatic polythiourea for capacitors

To improve the dielectric performance of polyvinylidene fluoride (PVDF), blend films based on PVDF and aromatic polythiourea (ArPTU) were prepared by the solution casting method. The blend films have higher dielectric constant (9.2) and lower loss at low fields (0.02 at 1 kHz) than a pure PVDF film (8.4, 0.05 at 1 kHz). More importantly, the blend films can also inhibit the early polarization saturation at low fields and result in the significant enhancement of the dielectric strength and increase in the energy density and reduction of loss at high fields. For the PVDF/ArPTU(90/10) film, the maximum operating electric field is about 700 MV m−1 and the released energy density can be up to 10.8 J cm−3 with an efficiency of above 83%. The X-ray diffraction data and atomic force microscopy images show that these blend films exhibit clear structural changes with an increasing percentage of ArPTU. It is proven that the increase of the β phase content and decrease of the crystalline grains in blend films are helpful to reduce the dielectric loss and enhance the dielectric strength.

Synthesis of Pt–Ni/graphene via in situ reduction and its enhanced catalyst activity for methanol oxidation

A simple in situ reduction approach was used to obtain Pt3Ni/reduced graphene oxide (rGO) with dominant {111} facets. The catalytic activity of Pt-Ni/rGO toward methanol electro-oxidation was studied by performing cyclic voltammetry. The Pt3Ni/rGO nanocatalysts exhibited improved catalytic activity and durability.

Phase-transfer interface promoted corrosion from PtNi10 nanoctahedra to Pt4Ni nanoframes

AbstractA novel two-phase approach towards the corrosion of PtNi10 nanoctahedra has been developed. In this strategy, the active component of Ni in oil-soluble PtNi10 nanoctahedra which resided in the upper toluene phase, suffered from etching and was then transferred into a lower aqueous phase with coordination by ethylenediaminetetraacetate (EDTA). Due to the existence of the phase-transfer interface promoted by EDTA, the corrosion reaction proceeded at an accelerated rate under the mild conditions. Specifically, the resultant products of octahedral Pt4Ni nanoframes were successfully fabricated for the first time, and PtNi4 porous octahedra could be obtained when the dosage of EDTA-2Na was reduced. After a systematic study of this two-phase system, a “synergetic corrosion” mechanism is proposed to account for the formation of octahedral Pt4Ni nanoframes, involving contributions from many species (i.e., O2, H2O, H+, OAm, and EDTA4−). As a result of the fascinating three-dimensional geometry of Pt4Ni nanoframes and PtNi4 porous octahedra, both of the corroded nanocrystals showed superior activity over the pristine PtNi10 nanoctahedra for ethanol electrooxidation in alkaline media and hydrogenation of nitrobenzene.

Hematite nanodiscs exposing (001) facets: synthesis, formation mechanism and application for Li-ion batteries

27 nm thick hematite nanodiscs have been prepared by a facile solvothermal method. The growth of Fe2O3 nanodiscs follows the precipitation–dissolution–growth mechanism, and the (001) facets are preferentially exposed since (001) facets are the densest and therefore most stable facets. In particular, outstanding rate and cycling capabilities have been demonstrated for the nanodiscs due to the reduced Li+ diffusion distance and enhanced reactivity of the nanosized structures.

Fabrication of 1D nickel sulfide nanocrystals with high capacitances and remarkable durability

Nickel sulfide (NiS) materials with a different 1D structure are successfully synthesized by strictly controlling the reaction time and temperature, using dodecanethiol as both solvent and sulfur source. The formation of the NiS nanomaterials results from a “dispersion–decomposition” mechanism. Remarkably, 1D NiS electrode materials show super specific capacitance and stability.