Advanced Materials Research Vols. 652-654

Abstract: Cu(OH)₂/N-TiO₂ compound heterojunction photcocatalyst was prepared via a facile precipitation method. The as-synthesized samples were characterized by means of X-ray diffraction (XRD), field-emission transmission electron microscope (FE-SEM), ultraviolet-visible light (UV-vis) absorbance spectra technologies. The results suggest the as-obtained samples are spherical structure with the diameter of approximately 10-20 nm, the absorbance intensity in the visible light range increased with the amount of deposited increased. Photocatalytic activities of samples were investigated under visible light and methyl orange (MO) acted as simulation pollutants. The catalytic ablity of the synthesized photocatalysts under visible light irradiation showed higher than that of N-P25(TiO2). The remarkable photocatalytic activities are due to the high-quality of composites structure and the driving force for electron transfer in nanoparticle.

Abstract: Three-dimensionally interconnected meso/mesoporous holmium doped titania nanoparticles had been successfully prepared by a sol-gel routine. The precursors were prepared by cohydrolysis reactions of Ti(OC₂H₅)₄/Ho(OC₂H₅)₆ coprecipitating around micells of cetyltrimethylammonium bromide processed by ultrasonic. The hierarchical meso/mesoporous material was proved by high resolution transmission electron microscopy and N₂ adsorption-desorption analysis. The results of selecting area electron diffraction pattern, Raman spectroscopy, and X-ray diffractometry in wide-angle range showed a crystal phase of anatase for the prepared material. The XPS spectroscopy analysis showed that Ti element exists in the Ti⁴⁺ form and the bonds of Ti-O-Ho/H and Ti-O-Ti exist in the surface of Ho³⁺ doped TiO₂. Phenol photodegradation in an aqueous medium was employed as a probe reaction to evaluate the photocatalytic reactivity of the catalyst. The catalyst which possessed a hierarchical meso/mesoporous structure being conducive mass-transferring and light-harvesting showed that a photocatalytic activity for phenol is about 3.3 times than that of commercial P25 titania under a very weak UV-Vis irradiation condition.

Abstract: Influences of the concentration of additive PEG and overpotential on the Nuclei population density of copper electrocrystallization on a glass carbon electrode (GCE) have been studied in this file. We characterized the experimental data extracted from Li’s work [10] with the least square method and exponential curves. The relationship of nucleation number density and overpotential follows the exponential function basically has been obtained by carrying on the data fitting to experimental data. And with a given overpotential, when inject PEG into acidic cupric sulphate electrolyte with a lower concentration, nucleation number density is reduced, but when the injection concentration of PEG is high enough, nucleation number density is increased instead. While with a certain concentration of PEG, as the overpotential more negative, the nuclei population density increased gradually, but if the injection concentration is low, the change of the growth rate of nucleation number density is not significant.

Abstract: Lanthanum tungsten was prepared by two step method with lanthanum oxide, hydrochloric acid and sodium tungstate. The products were characterized by several analytical methods. Fourier transform infrared spectroscopy was used to determine whether the product was Lanthanum Tungsten. X-ray technique was used to study the phase composition. Scanning electron microscopy and scanning probe microscope were used to study micro-structure and surface morphology of powders. X-ray fluorescence spectrometer was used to study its content and impurity. DSC-TG was used to study its thermal stability. The results show that the prepared product is made of lanthanum tungsten mainly, its content of impurity is 3.91%, and there are traces of water in the powder. The prepared lanthanum tungsten has amorphous structure, the thermal stability is good, the powder grains present oval shape, and the diameter of grain is less than 1μm, the powder grains reunit partially.

Abstract: Zinc borate Zn2B6O11•7H2O was prepared at room temperature using Na2B4O7•10H2O, ZnSO4•7H2O and H3BO3 as raw materials. The synthesized product was characterized by XRD, SEM, TG-DSC and FT-IR. SEM results showed that the synthesized zinc borate had uniform morphology with a length up to a few microns. The experiment result indicates that additional H3BO3 in starting materials was beneficial to the uniform morphology of Zn2B6O11•7H2O.

Abstract: The periodic bridged amine-functionalized mesoporous organosilica (BAFMOs) was synthesized by condensation of bridged silicon precursor 1,2-Bis(triethoxysilyl)-ethane (BTESE) and Bis(3-(methylamino)propyl)-trimethoxysilane (BTMSPMA) under acidic conditions with the aid of NaCl and ethanol. A triblock copolymer P123 was used as template. X-ray diffraction and transmission electron microscopy revealed that the resultant BAFMOs materials possess ordered mesoporous. N₂ sorption showed that the specific surface area gradual decreased, from 970m²/g to 795m²/g, whereas the average pore size increased, from 3.7 nm to 5.4 nm as the amount of BTMSPMA increased. ¹³C CP MAS NMR and ²⁹Si MAS NMR confirmed the retaining of the Si-C as well as the existing of the amino in the silica skeleton. The analytical potential of the materials is demonstrated with separation of isomeric molecules in reverse phase chromatography mode compared with commercial C18 column.

Abstract: We have studied the structures and electronic properties of PdCn (n=2-12) using the density functional theory in this paper. Though calculating, we found that the linear isomers are most stable for PdCn(n=2-9) clusters. N=10 is turning point, and the bicyclical structure is most stable for PdC10 cluster. Cyclic structures have the lowest energy for PdC11 and PdC12 clusters.

Abstract: A direct methanol fuel cell (DMFC) with a novel double-layer structured membrane electrode assembly (MEA) was developed and a better performance was obtained. The double catalytic layer anode is composed of a hydrophilic inner catalyst layer with PtRu black and an outer catalyst layer with PtRu/C. In the double-layer structured anode, there existed a catalyst concentration gradient and porosity gradient, resulting in good mass transfer, proton and electron conducting. Furthermore, the delamination of the catalyst layer from the membrane was also resolved because of the inner hydrophilic catalyst film. To optimize the combination of the two catalysts layer a one-dimensional model based on Tafel type kinetics and semi-empirical mass transport coefficient was applied. The simulation of anode overpotential versus PtRu Blk inner layer thickness and PtRu/C outer layer thickness results showed a direct methanol fuel cell with a 5m thick inner PtRu black catalyst layer and an 8m thick outer 40wt%PtRu/C catalyst layer as anode electrode was the best.

Abstract: LiMn₂O_4-yF_y were synthesized by a novel method named liquid phase flameless combustion reaction with LiNO₃, MnAc₂.4H₂O and LiF as raw materials calcined at 600 °C for 3 h with HNO₃ as aided oxidant. All samples were investigated by X-ray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and electrochemical performance. The results show that: all samples have main phase of LiMn₂O₄ with impurity of Mn₃O₄ and the vibrational bands of Mn-O are a little red shift by doping F, which indicated that the F- enter the host structure of LiMn₂O₄ successfully. The electrochemical performance show that the initial discharge capacities of F-doped samples are lower than pristine LiMn₂O₄, which is 117.7 mAh•g^-1. However, the capacity retention of LiMn₂O_3.96F_0.04 and LiMn₂O_3.90F_0.10 are 73.6% and 74.5%, respectively, which are higher than pristine LiMn₂O₄, which is only 69.0% after 40 cycles.

Abstract: In order to improve burning-out characteristic of dry distillation coal tar, the sample of dry coal tar was investigated by thermo-gravimetric analyzer(TGA), and the sample’ properties of kinetics and burning-out were studied. The results show that the dry distillated tar combustion is mainly dynamic combustion with diffusive combustion as a supplement. The combustion activation energy was 30 kJ/mol above, but the activation energy, frequency factor and reaction order appeared change on the subsequent combustion. The dry distillated coal tar is easy to be ignited, but difficult to burn out, so its maximum burn out temperature is higher.