Kaibin Tang

Synthesis of MnO@C core–shell nanoplates with controllable shell thickness and their electrochemical performance for lithium-ion batteries

MnO@C core–shell nanoplates with a size of ∼150 nm have been prepared via thermal treatment deposition of acetylene with the precursor of Mn(OH)2 nanoplates, which has been hydrothermally synthesized. The thickness of the carbon shells varied from ∼3.1 to 13.7 nm by controlling the treatment temperature and reaction duration time. The electrochemical performance of the MnO@C nanoplates, which were synthesized at 550 °C for 10 h with a carbon shell thickness of ∼8.1 nm, display a high reversible capacity of ∼770 mA h g−1 at a current density of 200 mA g−1 and good cyclability after prolonged testing, which is higher than that of MnO@C nanoplates with a carbon shell thickness of ∼3.1, 4.0, 4.2, 10.9 and 13.7 nm.

Benzene-thermal preparation of nanocrystalline chromium nitride

Abstract Nanocrystalline CrN was successfully prepared through the liquid–solid reaction of anhydrous CrCl 3 and Li 3 N, via a benzene–thermal method in the temperature range of 350–420°C, which is much lower than that used in conventional methods. This process is simple and easy to control. X-ray diffraction (XRD) indicated that the compound was cubic CrN phase with cell constant a = 4.13 A. Transmission electron microscopy (TEM) images showed that the average particle size was about 25 nm. X-ray photoelectron spectroscopy (XPS) indicated that the as-prepared products contained a small amount (less than 20%) of amorphous carbon.

Hydrothermal preparation of CuGaS2 crystallites with different morphologies

Abstract The CuGaS2 crystallites with different morphologies were prepared at 160xa0°C through hydrothermal process by using CuCl, GaCl3 solution, and thiourea as source materials. The samples were characterized by means of X-ray powder diffraction, element analysis, transmission electron microscopy, and photoluminescence (PL). In present route, as-prepared CuGaS2 crystallites displayed spherical and whisker-like nanoparticles and snowflake-like micrometer particles. Room temperature PL spectrum of the snowflake-like crystallites exhibits a weak emission band at 540xa0nm and a broad strong emission band at 735xa0nm. The role that the reaction media played in the morphologies of the CuGaS2 crystallites was investigated, and a possible reaction mechanism was proposed.

Preparation and phase control of nanocrystalline silver indium sulfides via a hydrothermal route

A hydrothermal route was proposed to prepare and control nanocrystalline silver indium sulfides (orthorhombic AgInS 2 , tetragonal AgInS 2 , and cubic AgIn 5 S 8 ). The reaction was carried out in an autoclave in the temperature range of 100–280 °C with AgCl, InCl 3 , and thiourea as reactants. X-ray powder diffraction patterns and transmission electron microscopy images showed that the products were AgInS 2 and AgIn 5 S 8 phases and well crystallized with grain diameter in the range of 20–70 nm. X-ray photoelectron spectra of the single AgIn 5 S 8 phase revealed the surface stoichiometry (AgIn 5.05 S 8.11 ), and its room temperature Raman spectrum showed a strong peak at 130 cm −1 and a weak peak at around 290 cm −1 . The influence of reaction temperature on the phases in the final products was investigated. A possible reaction mechanism of the formation of silver indium sulfides was also briefly discussed.

Synthesis of FeP2/C nanohybrids and their performance for hydrogen evolution reaction

Phosphorous-rich FeP2/C nanohybrids are synthesized via the pyrolysis of ferrocene (Fe(C5H5)2) and red phosphorus in an evacuated and sealed quartz tube at 500 °C. The nanohybrids contain orthorhombic FeP2 with conical carbon tubes. Based on the calculated electroactive surface area, the performance of the FeP2/C nanohybrids as a novel non-noble metal electrocatalyst for hydrogen evolution reaction (HER) in 0.50 M H2SO4 is investigated. These nanohybrids show good catalytic activity and stability in the acidic medium and might serve as a promising new class of non-noble metal catalysts for practical HER.

Synchronously synthesized core–shell LiNi1/3Co1/3Mn1/3O2/carbon nanocomposites as cathode materials for high performance lithium ion batteries

LiNi1/3Co1/3Mn1/3O2/carbon core–shell nanocomposites with sizes of ∼100 nm and carbon shell thicknesses of ∼6 nm are obtained by a modified Pechini process, in which LiNi1/3Co1/3Mn1/3O2 is formed synchronously with a carbon coating in the presence of polyethylene glycol-600. Electrochemical measurements show that the nanocomposites deliver a stable discharge capacity of 175 mA h g−1 at 1 C and a capacity decay rate of <3% after 100 cycles. The effects of synthesis temperature on the electrochemical performance of the nanocomposites are examined, which shows that the discharge capacities increase from 154 to 175 mA h g−1 as the temperature increases from 800 to 1000 °C. Meanwhile, the electrochemical performances of the nanocomposites with carbon content varying from 0 to 20.8% are examined. Among these composites, that with 15.5% carbon content exhibits the highest and most stable discharge behaviour at 1 C for 100 cycles.

Hydrothermal synthesis of layered Li1.81H0.19Ti2O5·xH2O nanosheets and their transformation to single-crystalline Li4Ti5O12 nanosheets as the anode materials for Li-ion batteries

Lithium titanate oxide hydrate (Li1.81H0.19Ti2O5·xH2O) nanosheets were prepared via simple hydrothermal treatment of the low cost tetrabutyl titanate in LiOH solution. The orthorhombic Li1.81H0.19Ti2O5·xH2O nanosheets with thickness less than 10 nm were single crystalline and grew along the (100) facet. Time-dependent experiments confirmed that the formation of Li1.81H0.19Ti2O5·xH2O nanosheets underwent a hydrolysis–Kirkendall effect–Ostwald ripening process. As these Li1.81H0.19Ti2O5·xH2O nanosheets calcined at 500 °C for 2 h, the Li4Ti5O12 nanosheets with thickness of 10–20 nm were synthesized. The Li4Ti5O12 nanosheets were single crystalline and grew along the (110) facet. As an anode material for rechargeable lithium-ion batteries, Li4Ti5O12 nanosheets delivered an initial discharge capacity of 183 mAh g−1 together with a discharge capacity of 160 mAh g−1 after 100 cycles at 1 C. The discharge capacity could reach up to 120 mAh g−1 even after 300 cycles at 10 C. The morphology of nanosheets with large BET value (155.5 m2 g−1) and the high lithium-ion diffusion coefficient (1.51 × 10−8 cm2 s−1) could be favorable for the enhanced high-rate performance.

Solvent–thermal preparation of nanocrystalline pyrite cobalt disulfide

Abstract Nanocrystalline pyrite cobalt disulfide has been successfully prepared using the solvent–thermal method by the reaction of anhydrous CoCl 2 with Na 2 S 3 at 180u2008°C, which is similar to the well known hydrothermal process, except that toluene is substituted for water. The sulfur-to-metal ratio of the as-prepared product is 1.99:1, which is determined by chemical analysis. X-ray diffraction analysis indicates that the product is a single phase of pyrite cobalt disulfide. No Co–O vibrations are found in the IR spectra. Transmission electron microscopy shows that the average particle size is about 22 nm.

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.

Synthesis of Mn3O4 nanowires and their transformation to LiMn2O4 polyhedrons, application of LiMn2O4 as a cathode in a lithium-ion battery

Mn3O4 n nanowires with diameter of ∼15 nm and a length of up to several micrometres have been hydrothermally synthesized at 200 °C for 15 h without any surfactants. It was investigated that during the formation process of Mn3O4 nanowires the length of the nanowires increased while the diameter did not obviously change. The coercivity of the Mn3O4 nanowires is up to 5600 Oe at 5 K. As these Mn3O4 nanowires were treated with LiOH by solid state reaction at 750 °C for 6 h, interconnected LiMn2O4 polyhedrons were obtained. The achieved discharge capacity of the LiMn2O4 polyhedrons was 115 mAh g−1 and they retained 98.3% of this capacity after 60 cycles at 0.1 C.