单晶和多重孪晶钯纳米粒子的可见光简易合成及其光、电性能（英文）

以氯化钯(PdCl_2)为金属前驱体,利用简易可见光辅助法制备具有单晶和多重孪晶结构的钯纳米颗粒。借助高分辨透射电镜(HRTEM),可见分光光度计以及循环伏安法研究了钯纳米粒子纳米结构和电化学性质。结果表明,不同纳米结构的形成取决于还原速率的控制。与多重孪晶结构的钯纳米颗粒不同,单晶钯纳米粒子在可见光区域表现了表面等离子共振吸收峰。通过比较单晶和多重孪晶钯纳米粒子氧化过程的电化学参数,表明多重孪晶钯纳米粒子对乙醇有较好的电催化活性和抗中毒能力。     

不同形貌银纳米结构的制备及其光学性质

以聚乙烯吡咯烷酮(PVP)作为表面活性剂,利用乙二醇还原体系合成了具有不同形貌的银纳米结构,并详细分析了这些银纳米结构的形貌和结构特征。通过紫外-可见吸收光谱检测分析了不同形貌银纳米结构的光学性质;并从实验和理论上详细研究了单根银纳米线的光波导特征。实验表明,单根Ag纳米线是非常有效的波导腔,入射光可通过存在于Ag纳米线表面的表面等离激元辅助在纳米尺度上有效地输运到纳米线最末端而再发射。     

硫化镉纳米结构的制备与光学性质研究

采用直接热蒸发CdS粉末的方法,在不同的生长条件下制备出CdS纳米线和纳米带材料并对其形貌、结构和光学性质进行了研究.CdS纳米线具有单晶结构,且生长方向具有择优取向,而其纳米带不具有上述结构特征.光致发光光谱研究发现,室温下纳米线只在508 nm出现了CdS的本征发射带.然而,纳米带存在2个明显的发光峰,中心峰位分别位于513 nm和756 nm.这2个发射峰可分别指认为CdS的本征发射和V_s~+空位引起的发射.     

纳米金红石型TiO2沉积制备云母钛纳米复合材料及其光学性质

研究在片状绢云母表面直接沉积纳米金红石型TiO2制备云母钛纳米复合材料的方法。结果表明：在制备的云母钛中,金红石型TiO2良好地结合在光滑的绢云母表面上,沉积颗粒呈岛状分布,且分散均匀。随着TiO2含量的增加,形成致密的TiO2涂层。低温下热处理云母钛复合材料时,云母钛的白度、亮度及反射系数会随着金红石TiO2含量的增加而提高。云母钛复合物的反射系数随着TiO2的结晶性的提高而增加。     

纳米钯活化液的制备及其性质表征

以氯化钯为原料,聚乙烯吡咯烷酮(PVP)为分散剂,聚乙二醇400(PEG)为还原剂,反应温度为150℃,成功制备出纳米钯活化液。采用激光动态散射和透射电子显微镜对纳米钯进行了表征。结果显示,在PVP分散剂的作用下,得到的纳米钯为球形、单晶、粒径为30～50 nm,无其他的氧化物存在。探讨了分散剂对合成纳米钯的影响,在还原剂PEG和分散剂PVP共同作用下,制备的纳米钯粒径大小均一,无团聚现象。     

金铜合金纳米团簇的制备、性质及应用研究进展

金属纳米团簇是一类新兴的纳米材料,它的直径为1～3 nm,通常由几个到几百个金属原子构成,具有精确的原子个数和空间结构。近几年,研究发现对金纳米团簇进行合金化能够使其产生独特的物理化学性质,超小的尺寸和可调的表面性质使金铜合金团簇(Au-Cu NCs)在催化、传感等方面表现出优良的应用前景。主要综述了近年来Au-Cu NCs的研究成果,总结Au-Cu NCs的制备方法和性质,概述其在传感、催化等领域的应用,探讨Au-Cu NCs研究中的问题,并对Au-Cu NCs的发展前景予以展望。     

银铜纳米枝晶的生长及光学吸收性质

通过电沉积法制备出了Ag - Cu纳米枝晶,并表征了样品的晶体结构、微观形貌以及光学吸收特性.结果表明:当Ag+:Cu2＞1时,制备出银铜纳米单相合金,Ag+:Cu2+＜ 1/4时,制备出银铜纳米双相合金.当E=-0.2V时,形成单个银铜纳米粒子和粒子团簇,吸收峰位于402 nm处:随着沉积电位的增加,形成纳米枝晶,且光学吸收峰发生蓝移.在不同成分的银铜合金中,当Ag+Cu2+=4:1时,形成银铜纳米枝晶,吸收峰在358 nm处,随着铜元素的增加,枝晶尺寸减小,光学吸收峰红移.结合电结晶理论和经典枝晶生长理论解释了Ag - Cu纳米枝晶的形成机制.     

Au-Pt双金属纳米粒子的制备及其电催化性质

在PEG10000/Vc/HAuCl4体系中,用Vc还原HAuCl4制备金纳米粒子,以所制备的金纳米粒子为晶种,通过控制HAuCl4与H2PtCl6的质量比,制备不同Pt/Au比的双金属纳米粒子,并进一步研究其对H2O2电化学氧化的催化作用。紫外-可见光谱(Uv-vis)、透射电子显微镜(TEM)、选区电子衍射(SAED)、X射线粉末衍射(XRD)等实验结果表明：Au-Pt双金属纳米粒子为面心立方结构的合金。用循环伏安法对Au-Pt双金属纳米粒子修饰的玻碳电极的电化学性能进行测试,结果表明：Au-Pt双金属纳米粒子对H2O2电化学氧化有一定的催化作用。催化效率随Au-Pt双金属粒子中Pt含量的增加而增加。     

Preparation of novel core-shell nanoparticles by electrochemical synthesis

Nanostructural gold/polyaniline core/shell composite particles on conducting electrode ITO were successfully prepared via electrochemical polymerization of aniline based on 4-aminothiophenol （4-ATP） capped Au nanoparticles. The new approach to the fabrication included three steps： preparation of gold nanoparticles as core by pulse electrodeposition; formation of ATP monolayer on the gold particle surface, which served as a binder and an initiator; polymerization of aniline monomer initiated by ATP molecules under controlled voltage lower than the voltammetric threshold of aniline polymerization, which assured the formation of polyaniline shell film occurred on gold particles selectively Topographic images were also studied by AFM, which indicated the diameter of gold nanoparticles were around 250 run. Coulometry characterization confirmed the shell thickness of polyaniline film was about 30 nm A possible formation mechanism of the Au/polyaniline core-shell nanocomposites was also proposed. The novel as-prepared core-shell nanoparticles have potential application in constructing biosensor when bioactive enzymes are absorbed or embedded in polyaniline shell film.     

Facile synthesis,morphology and structure of Dy_2O_3 nanoparticles through electrochemical precipitation

The aim of this research was to introduce a new, facile and simple method for synthesis of Dy_2O_3 nanostructures at room temperature. For the first time,galvanostatic electrodeposition was used to synthesize Dy_2O_3 particles, and the influence of the current density on the structure and morphology of the product was studied.The samples were characterized by X-ray diffraction(XRD), transmission electron microscopy(TEM) and Brunauer–Emmett–Teller(BET). The results show that the current density has little effect on the chemical composition but great effect on the structure and morphology of the samples. The average size of the particles decreases as the applied current density increases. The grain size of asprepared samples decreases from 500 to 70 nm when the current density increases from 0.5 to 6.0 mA·cm~(-2). To obtain oxide product, the as-prepared samples were heattreated at 1,000 °C. The results show that the heat-treated samples have smaller particles. The XRD results show that the similar patterns are observed in the samples synthesized at different current densities, and the only difference from the JCPDS card is the ratio of peak intensities. With the increase in the current density, a decrease in the current efficiency is observed.     

Preparation and characterization of polyvinylchloride membrane embedded with Cu nanoparticles for electrochemical oxidation in direct methanol fuel cell

Copper nanoparticles were prepared by the chemical reduction method. These copper particles were embedded into the polyvinylchloride (PVC) matrix as support and used as an electrode (PVC/Cu) for the oxidation of methanol fuel for improving the current response. The PVC/Cu electrodes were characterized by thermal gravimetric analysis (TGA) for thermal stability of the electrode, X-ray diffraction (XRD) for identification of copper nanoparticles in the electrode, Fourier transform infrared spectroscopy (FTIR) to identify the interaction between PVC and Cu and scan electron microscopy (SEM) with EDAX for the morphology of the electrode. The electrocatalytic activity of the electrode was characterized by the cyclic voltammetry, linear sweep voltammetry, and chronoamperometry techniques. An increase in the electrode activity was observed with the increase of copper quantity from 0.18 g (PVC/Cu-0.18 g) to 0.24 g (PVC/Cu-0.24 g) and the maximum was found at 0.24 g of copper in the electrode. Also, it was observed that the electrode achieved the maximum catalytic current in 0.5 mol/L CH₃OH + 1 mol/L NaOH solution. FTIR identified that water molecules, C—H group, copper nanoparticle and its oxide were available in the electrode. SEM images with EDAX showed that copper particles were properly embedded in the polyvinylchloride matrix.     

Crystal structure and switchable optical properties of yttrium hydride films covered by palladium layer

1　INTRODUCTIONTherare earthhydridefilmswithswitchableop ticalpropertieswerefirstlydiscoveredbyHuibertsetal[13] andhaveattractedmoreandmoreinterestre cently .Huibertsetal[1,2 ] foundthatthefilmsofYHxandLaHx exhibitremarkablereversiblechangesintheiropticalpropertiesduringhydrogenation/dehy drogenationprocess .Bychangingthehydrogen gaspressureorbyelectrochemicalmeans,thefilmscanbecontinuouslyandreversiblyswitchedfromashinymirrortoatransparentwindowinafractionofasec ond[3,4 ] .Thesubsequen…     

GaN/PMMA nanocomposite：synthesis and optical properties

High crystalline quality wurtzite-GaN nanoparticles, with diameters of about 11 nm, well dispersed in a poly-methyl methacrylate polymer matrix, were synthesized using a routine two-step route and were structurally and optically characterized.The as-prepared composite showed three broad overloading photoluminescence emission peaks with centers at 3.45, 3.29, and 3.10 eV.The 3.45 eV emission band is assigned to the recombination of the free exciton of GaN particles.The other two emission peaks possibly origi...     

Cu对Sn-Co/C复合材料结构和电化学性能的影响

分别以单质Cu粉和CuCO3.Cu(OH)2为Cu源,采用固相烧结法制备锂离子电池Sn-Co-Cu/C复合材料,利用SEM、XRD和电池程控测试仪研究Cu对材料结构和电化学性能的影响。结果表明:Sn-Co/C复合材料由CoSn相和微量CoSn2组成,添加Cu粉或CuCO3.Cu(OH)2的Sn-Co-Cu/C均由大量CoSn、α-Co3Sn2和少量CoSn2组成;添加的Cu固溶于Sn-Co合金,使颗粒细化,同时比表面积也增大。添加Cu粉和CuCO3.Cu(OH)2的Sn-Co-Cu/C的首次充电、放电容量分别为467、319 mA.h/g和489、326 mA.h/g,经过40次循环后容量保持率分别为83.4%和86.8%;添加Cu导致多相的形成以及颗粒的细化,增加了Li+的扩散通道和增强了材料的结构稳定性,从而显著改善了材料的电化学性能。     

Bridge effect of silver nanoparticles on electrochemical performance of graphite nanofiber/polyaniline for supercapacitor

In this work, silver (Ag) nanoparticles were deposited onto graphite nanofibers (GNFs) by chemical reduction while polyaniline-coated Ag-GNFs (Ag-GNFs/PANI) were prepared by in situ polymerization. The effect of the Ag nanoparticles intercalated in composite interface on the electrochemical performances, such as CV curve, charge–discharge behaviors, and specific capacitance of the GNFs/PANI was investigated. It was found that nano-sized Ag particles could be uniformly deposited onto the GNFs and that Ag-GNFs were successfully coated by PANI via in situ polymerization. According to the charge–discharge curves, the highest specific capacitance (212 F/g) of the Ag-GNFs/PANI was obtained at a scan rate of 0.1 A/g, as compared to 153 F/g for GNFs/PANI and 80 F/g for PANI. This indicated that the Ag nanoparticles that were deposited onto the GNFs led to a bridge effect between GNFs and PANI to improve the charge transfer, which resulted in the enhanced electrochemical performances of the composites due to a synergistic effect.     

Solid-state synthesis and electrochemical properties of SmVO4 cathode materials for low temperature SOFCs

A new cathode material fabricated by solid state reaction method was reported. The SmVO4 powder was obtained by firing the mixture of Sm2O3 and V2O5 powders in the temperature range of 700-1200 ℃. Its structure was identified by X-ray diffraction method and the electrochemical properties of SmVO4 as cathodes for solid oxide fuel cells (SOFCs) were investigated in single unit cell at the temperature ranged from 450-550 ℃. The results of the single fuel cell unit show that the maximum current densities are 641, 797, 688 mA·cm-2 and the maximum power output are 165, 268, 303 mW·cm-2 and the open circuit voltage are 1.04,0.96,0.92Vat 450, 500 and 550 ℃, respectively.     

Low-temperature solid-state synthesis and optical properties of CdS-ZnS and ZnS-CdS alloy nanoparticles

A simple low-temperature solid-state synthetic method was employed to obtain ZnS-CdS and CdS-ZnS alloy nanoparticles. The effects of reaction sequence, reactant molar ratios, and synthesis temperature on the products were investigated. The crystal structure and morphology of the products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and fourier transform infrared (FT-IR) spectroscopy. The results show that the products are alloy nanoparticles with a cubic phase structure. The formation mechanism of the alloy nanoparticles is briefly discussed. Sufficient grinding and crystalline water may be essential to form alloy nanoparticles. Ultraviolet-visible (UV-vis) spectra show that the edge absorptions of the CdS-ZnS and ZnS-CdS nanoparticles were located between those of ZnS and CdS bulks, and the absorbance at the peak maximum was practically dependent on reaction temperature, reaction sequence, and molar ratio. Extrinsic deep-level emission resulted in strong peaks in the photoluminescence (PL) spectra. The position and intensity of the emission peaks varied with the conditions during synthesis.