Advanced Materials Research Vols. 287-290

Abstract: Pured ZnO, Al doped ZnO and Al-In co-doped ZnO nanopowders were synthesized by the methanol alcoholysis method at 130 °C. Structure, morphology and optical properties of ZnO nanopowders were characterized using X-ray diffraction, Transmission electron microscopy (TEM), Fourier transform infrared (FTIR) and Photoluminescence (PL) spectra. The results show that ZnO nanopowders can be obtained in methanol solution at low temperature (130 °C). TEM images show that Al doped ZnO nanocrystals grow along the [002] axis quicker than other axes. FTIR spectra show that ZnO nanocrystals synthesized by the methanol alcoholysis include a little organic impurity. PL spectrums reveal that pure ZnO and doped ZnO nanocrystals have a blue band emission at 440 nm and a green band emission at 520 nm and 530 nm, respectively. Compared with the pure ZnO nanocrystal, the Al doping improves the luminescent properties.

Abstract: The (111)-p-Cu₂O/(0001)-n-ZnO heterostructure was successfully fabricated using low-temperature electrodeposition method on Au(111)/Si(100) substrate. The ZnO film deposited at positive current density was composed of aggregates of isolated hexagonal columnar grains, and the interface between ZnO and Cu₂O layer was clearly observed. (0002)-oriented continuous ZnO layer deposited on the (111)-Cu₂O layer at negative current density, but the metallic Cu layer was formed between ZnO and Cu₂O layers by reducing Cu₂O to Cu during ZnO deposition. The Cu₂O/isolated-ZnO heterostructure showed ohmic feature, and (111)-Cu₂O/Cu/(0002)-ZnO heterostructures showed an excellent rectification with rectification ratio of 85.

Abstract: The effect of carbon nanotubes (CNTs) addition on the electrochemical performance of Al doped α-nickel hydroxide is studied. The microstructure and electrochemical performance of the prepared samples are characterized by XRD,SEM, electrochemical impedance spectroscopy, charge-discharge at different rate, and Charge-discharge cycling stability tests. The results show that the addition of CNTs could decrease the electrochemical reaction impedance dramatically, increase the specific discharge capacity at higher rate, and improve the Charge-discharge cycling stability reversibility.

Abstract: Highly porous carbons were prepared from sunflower seed shell (SSS) by chemical activation and used as electrode material for electrochemical double layer capacitor (EDLC). The surface area and pore structure of the porous carbons are characterized intensively using N₂ adsorption technique. The results show that the pore-structure of the carbons is closely related to activation temperature. Electrochemical measurements show that the carbons have excellent capacitive behavior and high capacitance retention ratio at high drain current, which is due to that there are both abundant macroscopic pores and micropore surface in the texture of the carbons. More importantly, the capacitive performances of these carbons are much better than ordered mesoporous carbons, thus highlighting the success of preparing high performance electrode material for EDLC from SSS.

Abstract: This paper describes the structural characteristics, manufacturing processes and quality problems of hand-pushing tapping knife for natural rubber tree milk and suggests several measures to improve its mechanical properties effectively by analyzing relevant factors that affect hand-pushing tapping knife’s mechanical properties.

Abstract: In order to synthesize the fine compound iron-doped nickel disulfide (NiS₂) with environmentally friendly nickel, sulfur and iron powders, mechanical alloying (MA) was conducted for 8 hrs with SPEX Mill at a speed of 1000 rpm. In this process, stearic acid was added as a kind of process control agents (PCAs) to prevent the excessive cold welding. Meanwhile, for the purpose of getting nanocrystalline of Fe-doped NiS₂ powder particles to improve the contact areas between the active materials, the wet milling process was also done for 30 hrs with normal hexane (C₆H₁₄) as a solvent PCA. The prepared powders were characterized by FE-SEM, XRD, EPMA, EDS and TEM. Finally, the charge/discharge properties of Li/Fe-doped NiS₂ cells were investigated at room temperature by employing 1 M LiCF₃SO₃ (lithium trifluoromethanesulfonate) dissolved in TEGDME (tetraethylene glycol dimethylether) as the electrolyte. The initial discharge capacity of Li/Fe-doped NiS₂ cell using wet milled powders as the cathode material is 792 mAh/g, which may indicate its high energy density and good future as cathode materials for lithium-ion batteries.

Abstract: A novel strategy was proposed to fabricate carbon fiber microelectrodes (CFMEs). The resultant CFMEs were characterized using scan electron microscopy (SEM) and cyclic voltammetry (CV). Compared to the conventional method, the proposed method only needs a simple heating step for achieving CFMEs without additional pulled, sealed and back-filled procedure. The electrochemical behaviors of 2,4-Dichlorophenol (2,4-DCP) at fabricated CFMEs in pH (2.0-9.0) was for the first time studied and demonstrated a two-charge and two-proton transference process.

Abstract: In this paper, a two-step method is adopted to add titania (TiO₂) nanoparticle and silica (SiO₂) nanoparticle in commercial water-based paint to form the nano-paint with various concentrations of the added nanoparticle. The paint is sprayed onto the steel plate to form a coated film as the test samples. The experiments are implemented in order to investigate the effects of the nanoparticle on reflection spectra, surface hydrophobic and heat transfer performance of the coated film. The experimental results show that adding the nanoparticle indeed has positive effects on the above properties. This research contributes to the development of the functional paint for various applications.

Abstract: We investigate the effect of hyperfine interaction on magnetoresistance in nonmagenetic organic semiconductors. A Lorentz-type magnetoresistance is obtained from hyperfine interaction-dependent spin precession picture. The magnetoresistance depends on initial spin orientation of electron to hole in electron-hole pairs. Increasing hyperfine interaction slows down change of the magnetoresistance with magnetic field. The field dependence, the sign and saturation value of the magnetoresistances are composite effects of recombination and dissociation rate constants of singlet and triplet electron-hole pairs.

Abstract: This study involved a two-step method of adding multi-walled carbon nanotube (MWCNTs) and alumina (Al₂O₃) nanoparticles to paraffin wax, forming nanocomposite-enhanced phase change materials (NEPCMs). The NEPCMs in a phase change experiment were influenced by the concentrations of the nano-materials and the heating temperature of water. The objective of this paper is to investigate the optimal parameters of added nano-materials. The experimental results show that the phase change temperature of the paraffin wax slightly increases after adding the nano-materials to the paraffin wax. In addition, the nano-materials in the paraffin wax will reduce the temperature difference between test samples and heating water, indicating that adding the nano-materials can effectively reduce the thermal resistance of the experimental samples and improve the efficiency of thermal energy storage.