金修饰纳米多孔Pd催化剂对甲酸氧化的电催化活性

以水热法制备出纳米多孔网状钯催化剂(nanoPd),采用电位扫描在其上沉积金,制成金修饰纳米钯电极(Au/nanoPd),运用循环伏安法(CV)、线性扫描(LSV)和交流阻抗谱(EIS)比较nanoPd和Au/nanoPd电极对甲酸氧化反应的电催化活性。CV和LSV结果表明:金在nanoPd表面的沉积促进钯对甲酸氧化的电催化活性,起始电位提前,电流密度更高。EIS研究结果也表明:在Au/nanoPd电极上,甲酸氧化反应的电荷传递电阻更低。结果表明:金修饰纳米钯电极(Au/nanoPd)对甲酸氧化具有较高的电催化活性。     

Hybrid solar cells based on dye-sensitized nanoporous TiO2 electrodes and conjugated polymers as hole transport materials

Solid state dye-sensitized photovoltaic solar cells were fabricated using a three-layer concept. The hybrid devices consist of a transparent inorganic nanocrystalline titanium dioxide (nc-TiO₂) layer with a thickness of 2 μm as electron acceptor and for electron transport. A surface-adsorbed RuL2(NCS)2:2 TBA dye complex (where L=2,2′-bipyridyl-4,4′-dicarboxylic acid; TBA=tetrabutylammonium) is utilized for light absorption and electron injection to the conduction band of TiO₂. For the transport of holes to the back contact electrode conjugated polymers are used, either a poly(3-octylthiophene) (P3OT), or a low band-gap thiophene–isothianaphthene-based copolymer (PDTI). These devices exhibit an overall energy conversion efficiency of approximately 0.16% under simulated solar irradiation (80 mW/cm²). Furthermore, we have investigated the surface network morphology of these film layers by atomic microscope (AFM) exploring strategies to improve the efficiency.     

Improved photovoltaic performance of dye-sensitized solar cells by carbon-ion implantation of tri-layer titania film electrodes

TiO2tri-layer structure films were modified by C-ions implantation for improving the photovoltaic performance of dye-sensitized solar cells(DSSCs), in which the structure of TiO2 changes from rutile to anatase and the sizes of TiO2 particles increase. The optimal concentration of ions implantation for C-implanted cells is 19 1015 atom cm-2,and the maximum conversion efficiency of 5.32 % is achieved(luminous intensity of 1 sun, light irradiance of AM1.5G),which is 25.2 % higher than that of unimplanted cell. The significant improvement in conversion efficiency by carbonion implantation is contributed to reducing charge recombination and enhancing the light-harvesting ability, as indicated from incident photon-to-collected electron conversion efficiency(IPCE) and ultraviolet-visible(UV-Vis) measurements. Furthermore, the charge carrier's lifetime in the trilayer titania films is prolonged after carbon-ion implantations.     

Porous carbon nanotube electrodes supported by natural polymeric membranes for PEMFC

A new type of porous multiwalled carbon nanotube (MWCNT) electrode with a macroporous networking inner-structure was prepared. First, the MWCNTs were homogeneously introduced inside and outside of a bacterial cellulose membrane with a 3D inter-connected network structure using ultrasound treatment and vacuum filtration in order to form the GDL. Second, the CL was formed on the surface of the GDL through vacuum filtration of the Pt incorporated MWCNTs (Pt/MWCNTs). Finally, the electrode was created through freeze-drying. The final electrode had a sheet resistance of 80 Ω/□ and an electro-chemical active surface area (ECSA) of 10.1 m²/g. Although the ECSA of the electrode did not have the efficiency (14.3 m²/g) of a typical electrode (carbon cloth/Pt/carbon black), these results suggested that the new type of electrode has potential as a proton exchange membrane fuel cell.     

Pb-free glass frits prepared by spray pyrolysis as inorganic binders of Al electrodes in Si solar cells

Pb-free glass frits prepared by spray pyrolysis for Al electrodes were of fine size, spherical morphology and dense structure. Their mean size and geometric standard deviation when prepared at 1,200 °C were 1.0 μm and 1.4, respectively. Their glass transition temperature (T_g) was 374 °C. An Al electrode formed from Al paste with glass frits had a dense structure and good adhesion to the Si substrate. It had a well-developed back-surface field layer of 17.5 μm thickness. Al electrodes formed from Al paste without glass frits had sheet resistances between 21 and 32 mΩ sq⁻¹ as the firing temperature changed from 600 to 900 °C. This compared with values from electrodes formed with frits that decreased from 20 to 7 mΩ sq⁻¹ over the same range of firing temperatures.     

脉冲电沉积制备电控离子分离NiHCF膜电极

采用脉冲电沉积法在石墨基体上制备了铁氰化镍膜(NiHCF膜).通过循环伏安法考察了不同脉冲参数(脉冲电压、脉冲周期、占空比、沉积次数)条件下制备的石墨基NiHCF膜电极的离子交换容量,并通过SEM和XPS分析了膜的表面形貌与组成.结果表明:脉冲电压0.3 V(vs SCE)、脉冲周期0.6 s、占空比为50%时沉积得到的NiHCF膜均匀致密,且具有较大的离子交换容量和良好的稳定性.脉冲电沉积法可用于制备性能优良的电化学控制离子分离膜电极.     

不同改性的MWCNTs负载Au催化剂电催化甲醇的研究

通过光化学还原法,以HAuCl4溶液为前躯体,用312nm的紫外光辐照,在20 min内合成了红色Au纳米粒子溶胶.用苯硫酚溶液和5wt％ HF溶液分别改性管径为20～40nm的多壁碳纳米管(MWCNTs),并将合成的Au纳米粒子负载在改性的MWCNTs表面,制备了不同方法改性的Au/MWCNTs纳米催化剂.TEM显示,Au纳米颗粒平均粒径为4.3 nm,在MWCNTs表面的负载效果是HF的改性明显好于苯硫酚.在KOH溶液碱性介质中,电化学测试表明,苯硫酚和HF两种不同方法改性后,Au/MWCNTs纳米催化剂对甲醇具有一定的电催化活性,但后者具有更高的催化活性和更好的稳定性.     

磁控溅射制备的Au-TiO2纳米棒阵列的光降解研究

首次通过磁控溅射制备了对齐的Au-TiO2纳米棒阵列,Au-TiO2纳米棒的制备通过直流反应磁控溅射法在室温中进行,之后在500oC的空气中热处理两小时,热处理导致Au-TiO2纳米棒的Au纳米粒子嵌入到锐钛矿相TiO2纳米棒中, 与传统方法制备的纯TiO2纳米棒相比, 这些Au-TiO2纳米棒表现出较低的光致发光强度和较高的光吸收性, 并且对可见光反应强烈. TiO2纳米棒中的Au纳米颗粒能够抑制电荷复合     

Substitution of ThO2 by La2O3 additions in tungsten electrodes for atmospheric plasma spraying

ThO₂ additions are commonly used in tungsten-based electrodes for plasma spraying due to the excellent electron emissivity, improved arcing behavior, higher strength, and better machinability. Because of their radioactive potential, which makes handling, use, recycling, and disposal more difficult, alternative additives are required that provide the same advantages as thoriated tungsten, but without environmental hazards. Within this work, tungsten cathodes with 2 wt.% ThO₂ and 1 wt.% La₂O₃ were compared with respect to their arc ignition behavior, plasma stability and arc erosion. Both, cyclic and continuous plasma spraying experiments were carried out. In addition, structure and mechanical properties of Al₂O₃ coatings sprayed on Mo substrates were evaluated. La₂O₃ is characterized by a similar plasma ignition and operation behavior as well as a comparable coating quality with respect to ThO₂ additions. Further, La₂O₃ additions caused a reduced degradation of the cathode material, which is attributed to the lower cathode temperature, giving rise to an expected longer lifetime.     

Au/CuMn催化剂对于C3H8还原NO催化性能的研究

以沉积-沉淀法制备了系列Au/CuMn催化剂,并对催化剂进行了XRD和XPS等表征,研究了Au负载量和催化剂焙烧温度对Au/CuMn催化剂性能的影响。实验结果显示,60℃烘干、Au理论负载量为3%的催化剂性能最佳,在50℃的反应条件下,NO的转化率达到72.4%,但催化剂失活较快。XPS分析显示,催化剂表面的Au3+与吸附氧物种Oads.是反应的活性中心,反应过程中催化剂表面氧化态Au3+与Oads.物种部分被还原,可能是催化剂失活的重要原因。另外,反应后在催化剂表面生成的亚硝酸盐、硝酸盐和碳酸盐等物种,覆盖了活性中心,也是导致催化剂失活的原因之一。     

Electrocatalytic performance of Pb−Ru pyrochlore prepared by the amorphous citrate precursor method for bifunctional air electrodes

Pb−Ru pyrochlore has been of interest as bifunctional electrocatalyst for an air electrode. An amorphous citrate precursor (ACP) process has been optimized to prepare Pb−Ru pyrochlore powders with high surface areas with consequent improvement of its electrocatalytic performance in an air electrode. The surface area of the final powder is 30 m²/g, which is larger than the value obtained by the conventional hydroxide method. A PTEF-bonded gas diffusion electrode loaded with pyrochlore catalysts prepared by the ACP method showed good bifunctional performance. The electrode loaded with only 10 mg/cm² of pyrochlore powder prepared by ACP showed good bifunctional performance, i.e. 100 mA/cm² for oxygen reduction and 100 mA/cm² for oxygen evolution, at 0.6 and 1.6 V vs. RHE, respectively. This performance compares well to the results from lower-area pyrochlore at much higher loading.     

Preparation by pulsed current electrochemical polymerisation and properties of ordered comb-shaped polyaniline/carbon fibres composites for flexible supercapacitor electrodes

ABSTRACT

Flexible polyaniline/carbon fibres (PANI/CFs) nanocomposites with comb-shaped polyaniline (PANI) nanorods were fabricated by using a one-step pulse current approach. The morphology, chemical structure, crystalline structure and electrochemical performances of well-controlled PANI/CFs composites were characterised and evaluated by FE-SEM, FT-IR, Raman spectra, XRD and electrochemical working station. The electrochemical performance of comb-shaped PANI/CFs nanocomposites as supercapacitor electrodes was obtained by controlling the polymerisation time and types of current. The optimised polyaniline/carbon fibres from preparation with pulse current for 7?min (PANI/CFs-PC-7) composite showed good electrochemical performance with maximum specific capacitance of 323?F?g^?1 of sample mass at a current density loading of 1?A?g^?1, together with better rate capability, bendability and good cycling stability, which are essential in high-performance supercapacitor electrodes. In addition, the highly efficient and convenient approach paves the way to large-scale commercial applications of the flexible ordered nanocomposites.     

Theory Research of Catalytic for Water-Gas Shift-Reaction by Copper Doping of TM Clusters (TM = Ag,Au)

Protection of Metals and Physical Chemistry of Surfaces - The catalytic activity of water-gas shift reaction catalyzed by Cu12TM (TM = Cu, Ag, Au) cluster is analyzed by density functional methods...     

Evidence for the formation of distorted nanodomains involved in the phase transformation of stabilized zirconia by coupling convergent beam electron diffraction and in situ TEM nanoindentation

The transformation of zirconia from its tetragonal to its monoclinic phase is an important feature of the zirconia system. First found to be an advantage due to its important toughening effect, it can also be very detrimental when it occurs in the framework of low-temperature degradation, particularly in the case of biomaterial applications. One way to avoid or to control this phase transformation is to understand how it initiates and more particularly the stress states that can trigger it. A new technique available inside a transmission electron microscope seems to be particularly well suited for that type of study: convergent beam electron diffraction, a well-known technique to reveal stresses, was coupled to in situ transmission electron microscopy mechanical nanoindentation. The experiments reveal the presence of sheared nanoregions at grain boundaries. These could act as embryos for tetragonal-to-monoclinic phase transformations. This is an important first step in the understanding of the earliest stage of zirconia phase transformation.     

Near-net-shape forming of metallic bipolar plates for planar solid oxide fuel cells by induction plasma spraying

In one of the present designs of solid oxide fuel cells (SOFC), metallic bipolar plates with gas channels on the surface are used, which consist of a chromium alloy and are manufactured by a time consuming and costly multistep process. To reduce the production time and costs, attempts were made to develop an alternative near-net-shape production method based on RF-induction plasma spray technology. With this process raw powders, as applied for the “conventional” sintering route as well as recycled powders from used bipolar plates, have been applied. The process parameters were adapted to both powders, and the obtained products were qualified. The near-net-shape production requires the formation of a gas channel structure already with the spray process using structured substrates. Therefore, different spray angles occur during the deposition process. The influence of the spray angle on the microstructure of the free-standing parts was investigated. The required gas tightness for grooved profiles with relatively large channel depths and widths can only be achieved using spray angles between 90° and approximately 60°. Then a tilting of the substrate and an adapted design of the gas channel profiles are needed to fulfill the structural requirements for the bipolar plates.     

Cu(In,Ga)Se_2 absorbers prepared by electrodeposition for low-cost thin-film solar cells

Reducing the manufacturing cost of solar cells is necessary to their industrial production. Electrodepositing is an effective, non-vacuum method which is very suitable for cutting the manufacturing cost of thin films as well as developing its large-scale industrial production. In this study, about 1-μm-thick Cu(In,Ga)Se_2(CIGS) precursors were electrodeposited on Mo/glass substrates in aqueous solution utilizing a three-electrode potentiostatic system.Triethanolamine was used as complexing agent, and all parameters of electrodeposition were precisely controlled.After that, the electrodeposited precursors were selenized in a Se atmosphere with different heating ramp rates(60 and 600℃·min~(-1)). High-quality CIGS films were obtained, and their characteristics were investigated by X-ray fluorescence, scanning electron microscopy, energydispersive spectroscopy, X-ray diffraction, Raman spectra and near-infrared-visible(NIR-Vis) spectra. The results reveal that there are many differences between the properties of the films under different heating rates. Finally,CIGS solar cells were fabricated using a fast and a slow heating rate. The maximum efficiencies achieved for the films selenized at 60 and 600℃-min~(-1) are 3.15% and 0.71%, respectively.     

Line-width of ion beam-modified polystyrene by negative carbon ions for fine adhesion pattern of mesenchymal stem cells

The fine adhesion pattern of mesenchymal stem cells (MSCs) on polytyrene (PS) was investigated by carbon negative-ion implantation with decreasing the implanted line-width. The carbon negative ions with certain ion fluence of 3 × 10¹⁴ ions/cm² and ion energy of 10 keV were implanted through the ridge-pattern mask having slit aperture from 0 to 40 μm. After 2 days of culture of rat MSCs on the modified PS, the MSCs elongated and adhered along the implanted region due to the lowering of contact angle after the ion implantation. The cells stained with fluorescent dye of DAPI were used to observe the position of cell adhesion on the modified line-width. By decreasing the line-width from 40 to 3 μm, we found the adhesion arrangements from the gathering cells to the individual cells. The most probable adhesions of the gathering cells in a lateral direction of the line were found at a wider width than 20 μm, while that of the individual cells were found at a width of about 10 μm. The adhesion arrangement of individual cells helped to increase the distances of cell-to-cell due to the elongated adhesion of cells along the narrowed implanted line-width. The number of adhered cells decreased with a decrease in the implanted line-width, and almost all of them had the same direction of their nucleus at the narrower line-width than 12 μm. Therefore, the controls of the individual cell-adhesion arrangement in a line and the nuclei direction could be achieved by decreasing the implanted line-width to about 10 μm.     

西红花酸对晚期糖化终产物诱导内皮细胞晚期糖基化终产物受体表达的抑制作用

目的: 研究西红花酸对晚期糖基化终产物(AGE)诱导牛内皮细胞(BEC)中晚期糖基化终产物受体(RAGE)mRNA表达的抑制作用,并探讨其可能机制。方法: 不同浓度的西红花酸(1、0.1、0.01 μmol/L)预孵BEC细胞12h后,用AGE(100 mg/L)刺激细胞12h,RT-PCR法测定RAGEmRNA的表达水平;ELISA法测定细胞间黏附分子-1(ICAM-1)的表达;试剂盒分别检测胞外超氧阴离子和硫代巴比妥酸反应产物(TBARS)浓度;同时,还用2,7-二氯荧光素(DCFH)测定了胞内H2O2的浓度,并用罗丹明123(Rh123)荧光法及MTT法分别检测细胞线粒体膜电位(MMP)水平和其琥珀酸脱氢酶(MSDH)的活性。结果: 与AGE模型组相比,西红花酸能显著抑制RAGEmRNA的表达(P<0.05),降低胞外超氧阴离子和TBARS(P<0.01或P<0.05)及胞内H2O2水平;结果还显示,西红花酸能提高细胞MMP水平和MSDH活性。对ICAM-1蛋白表达也有抑制作用,且呈时间和剂量依赖性。结论: 西红花酸可能通过清除AGE与RAGE结合产生的活性氧(ROS)来抑制RAGEmRNA的高表达。提示西红花酸对糖尿病血管病变有潜在的治疗价值。