Dake Wang

Facile synthesis of novel tunable highly porous CuO nanorods for high rate lithium battery anodes with realized long cycle life and high reversible capacity.

Various CuO nanostructures have been well studied as anode materials for lithium ion batteries (LIBs); however, there are few reports on the synthesis of porous CuO nanostructures used for anode materials, especially one-dimensional (1D) porous CuO. In this work, novel 1D highly porous CuO nanorods with tunable porous size were synthesized in large-quantities by a new, friendly, but very simple approach. We found that the pore size could be controlled by adjusting the sintering temperature in the calcination process. With the rising of calcination temperature, the pore size of CuO has been tuned in the range of ∼0.4 nm to 22 nm. The porous CuO materials have been applied as anode materials in LIBs and the effects of porous size on the electrochemical properties were observed. The highly porous CuO nanorods with porous size in the range of ∼6 nm to 22 nm yielded excellent high specific capacity, good cycling stability, and high rate performance, superior to that of most reported CuO nanocomposites. The CuO material delivers a high reversible capacity of 654 mA h g(-1) and 93% capacity retention over 200 cycles at a rate of 0.5 C. It also exhibits excellent high rate capacity of 410 mA h g(-1) even at 6 C. These results suggest that the facile synthetic method of producing a tunable highly porous CuO nanostructure can realize a long cycle life with high reversible capacity, which is suitable for next-generation high-performance LIBs.

Facile synthesis of nanocrystalline-assembled bundle-like CuO nanostructure with high rate capacities and enhanced cycling stability as an anode material for lithium-ion batteries

In this work, nanocrystalline-assembled bundle-like CuO structures were successfully synthesized in large-quantity by a friendly, facile two-step process. The bundle-like CuO particles are produced by thermolysis of bundle-like Cu(OH)2 precursors, which exhibit excellent high specific capacity, high stability, and especially high rate performance for anode materials in lithium-ion batteries, superior to that of most reported CuO-based anodes. The assembled structure of CuO endows it with high rate capacities of 666 mAh g−1, 609 mAh g−1, and 499 mAh g−1 at a current rate of 0.3 C, 1 C and 2 C after 50 cycles, respectively. Even at a high rate of 6 C, the bundle-like CuO can still deliver a capacity of 361 mAh g−1. It is observed that the electrochemical performance of the nanocrystalline-assembled bundle-like CuO is much better than that of CuO nanoparticles obtained by destroying the assembled bundle-like CuO through grinding. XRD analysis of both the electrodes after ending the discharge/charge proved that during the discharge/charge process, the conversion reactions occurring in the assembled structures have better reversibility, leading to the high rate capacity and cycling performances. The better reversibility originates from the better contact area for CuO/electrolyte, enhancing many sites to the access of Li+ in the electrolyte Li+. In addition, the assembled bundle-like CuO architectures can also relieve the volume variations during the Li+ uptake–release process, which also contributes to the excellent electrochemical performance. The high rate capacity and enhanced cycling stability of the bundle-like CuO structure make it a promising candidate as an anode material for high-performance Li-ion batteries.

Single-crystalline ZnSn(OH)6 hollow cubes via self-templated synthesis at room temperature and their photocatalytic properties

The synthesis of single-crystalline hollow particles with well-defined non-spherical shapes, especially hollow complex compounds, remains a significant challenge. In this paper, single-crystalline ZnSn(OH)6 (ZHS) hollow cubes were first synthesized by a facile self-templating method at room temperature. On the basis of X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy and transmission electron microscopy, it was found that hollow ZHS cubes were formed by a two-step process, in which solid cubes of ZHS were formed in the first step due to the co-precipitation of Zn(II) and Sn(IV) under basic conditions and then the solid cubes as the self-templates were converted to hollow ones through an alkali-assisted dissolution process. During the process, NaOH solution added in the second step is critical to the formation of ZHS hollow structures. The photocatalytic activity of ZHS hollow cubes for phenol degradation was tested, which showed much higher catalytic activity than that of the solid ZHS cubes. After four trials, the photocatalytic activity of the ZHS hollow cubes exhibits no significant loss.

Facile synthesis and characterization of CuInS2 nanocrystals with different structures and shapes

CuInS2 nanocrystals were synthesized by one-pot thermolysis of a mixture solution of metal chlorides, 1-dodecanethiol (DT) and oleic acid in noncoordinating solvent 1-octadecene. Interestingly, in this synthesis, different structures and shapes were obtained by simply varying the dosage of DT. At a low dosage of DT, wurtzite nanoplates formed in the initial reaction stage and then they further grew to nanoplates with wurtzite–zincblende polytypism as the reaction proceeded. On the contrary, a high dosage of DT produced zincblende nanoparticles. The formation processes of nanoplates and nanoparticles were studied and a growth mechanism was proposed. Our research will aid in solution-synthesis of ternary chalcogenide nanocrystals and the development of their optoelectronic devices.

Facile synthesis of AgInS2 hierarchical flowerlike nanoarchitectures composed of ultrathin nanowires

In this work, AgInS(2) hierarchical flowerlike nanoarchitectures, which are composed of ultrathin nanowires, were synthesized by thermolysis of a mixed solution of AgNO(3), InCl(3)·4H(2)O and n-dodecanethiol at elevated temperature. The average diameter and length of the nanowires composing the nanoarchitectures can reach 5 nm and ∼300 nm, respectively. We investigated the growth process of the nanoarchitectures and the effects of reaction parameters by XRD, SEM and TEM. In particular, the use of InCl(3)·4H(2)O played a decisive role in the synthesis of the nanoarchitectures. Moreover, it was found that polyhedra formed in the initial reaction time, and then the nanowires grew on the facets of these polyhedra, which resulted in the nanoarchitectures. The reaction temperature and the concentration of metal salts could influence the size of the nanowires.

Simple self-assembly of HLaNb2O7 nanosheets and Ag nanoparticles/clusters and their catalytic properties

HLaNb2O7 nanosheets and Ag nanoparticles/clusters were assembled to produce a novel 3D metal/semiconductor hybrid material (Ag/HLaNb2O7) by direct reaction of the undried D-glucopyranose derivative of HLaNb2O7 with [Ag(NH3)2]+ ion aqueous solution. The as-prepared samples were characterized using X-ray diffraction, scanning electron microscopy, transmission electron microscopy, UV-visible diffusive reflectance spectroscopy and nitrogen adsorption–desorption isotherms. The results showed that the simple self-assembly of HLaNb2O7 nanosheets and Ag nanoparticles/clusters formed a mesoporous material with a broad pore size distribution in the range of about 10–35 nm. The mesopores derived from the interspaces between HLaNb2O7 nanosheets and were attributed to Ag nanoparticles, rather than Ag clusters in the interlayer space of HLaNb2O7. The catalytic activity experiments revealed that the product (Ag/HLaNb2O7) was an excellent catalyst for the catalytic reduction of 4-nitrophenol (4-NP) and rhodamine B (RhB) by NaBH4 aqueous solution.

A new carbon intercalated compound of Dion–Jacobson phase HLaNb2O7

Carbon was successfully intercalated into the interlayer space of the Dion–Jacobson type layered perovskite HLaNb2O7 by pyrolysis of the precursor of a D-glucopyranose derivative of HLaNb2O7. Firstly, the D-glucopyranose derivative of HLaNb2O7 (D-glucopyranose-HLaNb2O7) was prepared by the grafting reaction between the n-decoxyl derivative of HLaNb2O7 and D-glucopyranose. The interlayer distance of D-glucopyranose-HLaNb2O7 was decreased to 15.4 A, compared to that of 27.6 A for n-decoxyl-HLaNb2O7. IR and solid-state 13C CP/MAS NMR spectra indicated that oxyalkyl chains were removed and glucopyranose rings were introduced. After pyrolysis of the D-glucopyranose derivative at 300 °C under flowing Ar, a novel intercalation compound of HLaNb2O7 with carbon (carbon-HLaNb2O7) was obtained. XRD pattern and HRTEM image both displayed the interlayer distance of about 12 A. Raman and solid-state 13C CP/MAS NMR spectra revealed that the intercalated carbon was mainly polycyclic aromatic carbon. The UV-VIS-near-IR spectrum showed that the carbon-HLaNb2O7 appreciably absorbed light at wavelengths below 855 nm and the band gap energy was only about 0.65 eV, which was much smaller than those of HLaNb2O7 and its derivatives, indicating that the intercalation with carbon can effectively modify the band gaps of Dion–Jacobson type layered perovskites.

A facile synthesis of highly porous CdSnO3 nanoparticles and their enhanced performance in lithium-ion batteries

CdSnO3 materials have been extensively studied as gas-sensing materials. However, there are few reports on the synthesis and use of porous CdSnO3 nanostructures for energy storage. Herein, we report highly porous CdSnO3 nanoparticles prepared using citric acid with sizes in the range of ∼7.8 nm to 28.7 nm and the application of these nanoparticles as an anode material for rechargeable Li-ion batteries (LIBs). Electrochemical measurements showed that the highly porous CdSnO3 nanoparticles delivered a high reversible capacity of ∼515 mA h g−1 for up to 40 cycles at a current rate of 70 mA g−1. Even at a high rate of 150 mA g−1, the porous CdSnO3 could still deliver a capacity of 506 mA h g−1. It is observed that the electrochemical performance of the highly porous CdSnO3 nanoparticles is much better than that (∼370 mA h g−1 for up to 40 cycles) of a counterpart obtained without citric acid, which also demonstrates the capacity enhancement and high rate capacity.

A FeSe-based superconductor (C 2 H 8 N 2 ) x FeSe with only ethylenediamine intercalated

A new FeSe-based superconductor (C2H8N2)x FeSe with ethylenediamine intercalated into FeSe was successfully synthesized by the solvothermal method, which is the first superconducting instance by metal-free organic molecule intercalation. Elemental analysis and TG-IR-GC/MS data reveal that the ethylenediamine molecules in the interlayer space are separate and intact. The X-ray diffraction (XRD) pattern indicates that the intercalation compound is an orthorhombic lattice rather than a tetragonal lattice applying to almost all the previous FeSe-based superconductors at room temperature. The magnetism measurements display a sharp superconducting transition at ∼10 K which is assigned to (C2H8N2)xFeSe, and a tiny drop in susceptibility at ∼30 K.摘要本文采用水热法成功合成了一种新型铁硒基超导体(C2H8N2)xFeSe, FeSe层间只有乙二胺分子而不包含其他任何金属. 碳氢氮元素分析和热重-红外-质谱联合分析的数据都表明层间的乙二胺分子是完整而且独立的. X射线衍射图指出插层化合物是一个正交格子, 而以往铁硒基超导体在常温下几乎都是四方格子. 磁性测量的数据显示产物在10 K左右有一个大的超导转变, 可归结于插层产物(C2H8N2)xFeSe. 此外, 在30 K处也观察到一个很小的超导转变, 这可能是杂质引起的.

Synthesis and structure of a new layered oxyfluoride Sr{sub 2}ScO{sub 3}F with photocatalytic property

Highlights: • A new oxyfluoride compound Sr{sub 2}ScO{sub 3}F was prepared by a solid state route. • The structure of this compound was determined by GSAS program based on XRD data. • The photocatalytic property was investigated under UV irradiation. - Abstract: A new Ruddlesden–Popper type scandium oxyfluoride, Sr{sub 2}ScO{sub 3}F, was synthesized by a conventional solid state reaction route. The detailed structure of Sr{sub 2}ScO{sub 3}F was investigated using X-ray diffraction (XRD) and selected area electron diffraction (SAED). The disorder distribution pattern of fluorine anions was determined by the {sup 19}F nuclear magnetic resonance (NMR) spectrum. The compound crystallizes in a K{sub 2}NiF{sub 4}-type tetragonal structure (space group I4/mmm) with O/F anions disordered over the apical sites of the perovskite-type Sc(O,F){sub 6} octahedron layers interleaved with strontium cations. Ultraviolet–visible (UV–vis) diffuse reflection spectrum of the prepared Sr{sub 2}ScO{sub 3}F indicates that it has an absorption in the UV–vis region. The photocatalytic activity of Sr{sub 2}ScO{sub 3}F was further investigated, showing an effective photodegradation of Rhodamine-B (RB) within 2 h under UV light irradiation.