水浴加热水解和微波加热水解法合成不同形貌的ZnO亚纳米粒子

以pH值为11.17的0.005 mol/L的ZnAc2和氨水的混合溶液为前驱体溶液,分别在80℃水浴中加热1 h合成了棒状ZnO亚纳米粒子,和在微波场（频率为2.45 GHz,功率为500 W）中加热2 min合成了花状ZnO亚纳米粒子.用X射线衍射仪和透射电子显微镜研究了产物的结构和形貌.结果表明：产物均为六方晶系ZnO,形貌分别为直径约100～300nm,长度约450～900 nm的棒状,和花瓣直径约为200 nm的花状结构.比较了采用这2种方法所得产物的形貌,并讨论了其形成机理.     

水热法制备Zn-Mg-Al花状水滑石

采用水热法,以尿素为沉淀剂,Zn(NO3)2、Mg(NO3)2和Al(NO3)3为原料,在120℃下连续反应10 h后制备了Zn-Mg-Al水滑石纳米片以及由纳米片组装成的花状结构水滑石。利用XRD、FTIR、TG-DTA、ICP和SEM分别对产物的尺寸、结构和形貌进行了分析。结果表明,合成的水滑石具有均一的花状形貌,花状晶体直径约8μm左右,构成花状结构的纳米片厚度约为100 nm,花状水滑石晶体具有良好的"记忆效应"。初步阐释了花状水滑石的可能形成机理。     

水热合成三维花状薄水铝石及其形成机理

在水溶液体系中,利用十六烷基三甲基溴化铵(CTAB)作为模板剂,水热合成了由纳米薄片自组装成的三维花状薄水铝石。采用XRD,SEM和TEM对其物相结构和形貌进行了分析,研究了反应温度和反应时间对产物形貌的影响。研究结果表明:在反应温度为160℃和反应时间为24h时,得到形貌规则统一、分散均匀的花状薄水铝石。该花状结构是由厚50nm的纳米薄片自组装而成,直径550～800nm,在其形成过程中,模板剂CTAB起到关键作用,并推断了纳米薄片自组装花状结构的形成机理。     

不同形貌氢氧化镍的可控合成

文章采用溶剂热法成功合成了棒状、管状和球状β-Ni（OH）2,用X射线衍射（XRD）和扫描电子显微镜（SEM）分别对产物的物质结构和形貌进行了表征。以扫描电子显微镜（SEM）为表征手段,考察了实验条件,如反应温度、时间等,对产物形貌的影响,并初步讨论了其形成机理。实验结果表明,在反应温度为130℃时,产物为微米棒,170℃时产物为微米管,反应温度升高至190℃时,产物为由纳米片构筑的球状结构。该合成方法简单、反应条件温和,是合成纳米材料的一种有效方法。     

棒状FeS2/NiS2和FeP/Ni2P材料的合成与催化性能比较

以Fe(NO3)3?9H2O、Ni(NO3)2?6H2O、硫粉或NaH2PO2?H2O为原料,通过两步法合成了FeS2/NiS2、FeP/Ni2P复合材料,通过XRD、SEM和TEM对材料的结构和形貌进行了表征,研究了其析氧催化性能。结果表明,上述催化剂均具有很好的催化性能。在电流密度为10 mA/cm2时,FeP/Ni2P需要较小的过电位（300 mV）,表现出比FeS2/NiS2（300 mV）更好的催化活性。FeP/Ni2P催化剂相应的塔菲尔斜率值（48 mV/dec）也比FeS2/NiS2 (71 mV/dec)的小,表示在析氧反应中FeP/Ni2P催化剂具有更好的催化动力学性能。     

基于片状前驱体组装中孔NiO微球

利用醇水混合溶剂作为反应介质,以硝酸镍(Ni(NO3)2.6H2O)为Ni源,尿素(CO(NH2)2)为沉淀剂,合成一种纳米片组装的碱式镍化合物微球,经热处理得到由NiO中孔纳米片组装的微球.采用X射线衍射仪、环境扫描电镜、傅立叶红外光谱仪和比表面及孔径分布测试仪对产物进行表征.结果表明:所得前驱体是一种片状结构的碱式碳酸镍盐(NiO2.45C0.74N0.25H2.90),经热处理后NiO纳米片单元上形成2.5和40 nm 2种孔径的中孔结构.改变尿素用量由0.01 mol增加至0.03 mol,会形成Ni(HCO3)2颗粒,从而改变微球表面形貌.结合PEG的模板作用和层状碱式金属盐类物质的成核及生长特性,提出了微米尺度球形组装NiO中孔纳米片的可能生长机理.     

[Bmim]FeCl4中金纳米材料的合成及其催化性能

在1-丁基-3-甲基咪唑四氯化铁盐([Bmim]FeCl4)中用油胺还原AuCl3制备了2种金纳米材料,研究了产物的形貌特征,考察了所制纳米材料催化NaBH4还原对硝基苯酚制备对胺基苯酚的性能.结果表明,产物形貌主要由[Bmim]FeCl4/油胺摩尔比决定,比值从0.5增至2,金纳米材料从枝状结构转变成花状结构,长径比约为10的棒变为径向长度200nm的片层;枝状纳米颗粒比花状纳米颗粒的催化性能好.     

Ti和NiTi表面Ni–Ti–O纳米层的显微结构及电催化性能

采用水热合成法在钛片和镍钛片表面制备了多种形貌的Ni–Ti–O纳米层。采用扫描电镜(SEM)和透射电镜(TEM)观察Ni–Ti–O纳米层的微观形貌。用循环伏安法初步研究了Ni–Ti–O纳米层对甲醇的催化氧化能力。结果表明:水热合成过程中溶液的Ti/Ni浓度比和基体材料种类对产物的微观形貌有重要影响。随着溶液中镍浓度的升高,纯Ti片上纳米层颗粒逐渐变小,分布变得均匀;NiTi片表面的纳米层则从纳米线束状结构转变为Ni–Ti–O纳米片结构。当溶液中无TiCl_4时,Ti片表面的产物为垂直于其生长的纳米薄片。与纯钛片相比,以镍钛合金片作为基体制备的电极对甲醇的电催化性能更好。     

水合硼酸锶纳米超结构的制备与表征

采用液相沉淀法,以氯化锶和硼酸氢铵为原料,制备了由纳米片组成的水合硼酸锶（SrB₆O₁₀·5H₂O）花状、枣状纳米超结构,并利用SEM、TEM、XRD进行了表征。化学分析及XRD结果表明,产物为单一SrB₆O₁₀·5H₂O相,纯度为99.5%。通过研究产物形貌结构随反应时间的演变过程,提出了水合硼酸锶纳米超结构的形成机理：反应初期晶核球形团聚,在此基础上晶核各向异性生长成片状结构,最终形成由纳米片组成的枣状或花状超结构。此外,研究了反应温度、反应物浓度等反应条件对产物形貌的影响。反应温度的升高使得纳米片尺寸增大,形状由不规则片状向矩形片状演变;团聚的有序度增加,产物形貌由无规则团聚体逐步演变为花状、枣状超结构。反应物浓度的降低,团聚体的有序度减小,产物中出现不规则团聚微球。     

稀土掺杂花状钨酸钙纳米晶溶剂 热法合成及其发光性能

以水-乙二胺二元溶剂热法及热处理合成了四方晶系稀土掺杂花状钨酸钙纳米晶。考察了混合溶剂比例、煅烧温度及掺杂稀土离子等条件对钨酸钙发光性能的影响,并分析了其形成机理。利用X射线衍射（XRD）、扫描电镜（SEM）、傅里叶变换红外光谱（FT-IR）和光致发光（PL）光谱等对钨酸钙结构、形貌及其性能进行了表征。结果表明：在水与乙二胺体积比为1∶2、反应温度为160 ℃、反应时间为24 h条件下合成前驱物,前驱物经800 ℃煅烧得到四方晶系稀土掺杂花状钨酸钙纳米晶;掺杂不同稀土离子得到在紫外光激发下发出不同颜色光的钨酸钙基荧光粉。     

One-step solution synthesis and formation mechanism of flower-like ZnO and its structural and optical characterization

The regular hierarchical flower-like ZnO nanostructures assembled by nanosheets were successfully synthesized by one-step solution route with citrate assistance at room temperature. It was demonstrated that the concentration of citrate and the molar ratio of Zn²⁺/OH⁻ had strong effect on the formation of nanosheets and self-assembly flower-like nanostructures. A reasonable formation mechanism of the flower-like nanostructures was proposed. According to UV–vis spectrum, the flower-like ZnO nanostructures exhibited strong light absorption, and the value of band gap of the obtained ZnO was estimated to be 3.26 eV. Moreover, the room-temperature photoluminescence (PL) spectrum of the sample presented only a near-band edge emission at 382 nm.     

Low temperature atomic layer deposition of nickel sulfide and nickel oxide thin films using Ni(dmamb)2 as Ni precursor

Nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)₂) with water and hydrogen sulfide as oxygen and sulfur sources was employed in atomic layer deposition (ALD) of nickel oxide (NiO) and nickel sulfide (NiS) thin films. Both NiO and NiS thin films demonstrate temperature-independent growth rates per cycle of 0.128?nm/cycle and 0.0765?nm/cycle, at 130–150?°C and 80–160?°C, respectively. Comparison of two nickel-based thin film materials demonstrates dissimilar deposition features depending on the reactivity of the Ni precursor, i.e., Ni(dmamb)₂ with anion sources provided by the water and hydrogen sulfide reactants. Difference in reactivity observed for NiO and NiS ALD processes is further investigated by density functional theory (DFT) simulations of surface reactions, which indicated that H₂S demonstrate higher reactivity with surface-adsorbed Ni precursor than H₂O. The material properties of ALD NiO and NiS thin films including stoichiometry, crystallinity, band structure, and electronic properties were analyzed by multiple experimental techniques, showing potential of ALD NiS as electrode or catalyst for energy-oriented devices.     

二硫化镍/氢氧化镍空心球的制备及其电容器性能研究

以均匀硫纳米球为硬模板，通过直接沉淀法在硫纳米球表面包覆一层氢氧化镍纳米片，得到均匀硫@氢氧化镍前驱体，前驱体经低温煅烧获得二硫化镍/氢氧化镍复合纳米空心球，用其制备的电极具有良好的电化学性能。通过X射线衍射和透射电镜等对复合材料的成分和形貌进行分析。结果表明：复合材料纯度较高，组分为二硫化镍和氢氧化镍，二者物质的量比约为1∶1；复合材料是大小均匀的多孔纳米空心球，空腔直径约为500 nm，表面覆盖超薄纳米片，长度约为250 nm，整体形如花球，大小约为1 μm。采用循环伏安、计时电位等方法对复合材料超级电容器性能进行研究。结果表明，在1 A/g电流密度下电极比电容达到1 446 F/g；在20 A/g电流密度下电极比电容仍高达976 F/g；在10 A/g电流密度下循环5 000次，电极容量保持率为86.4%，具有良好的倍率性能和循环稳定性。     

Design of NiS/CNTs nanocomposites for visible light driven catalysis and antibacterial activity studies

The outstanding photocatalytic activity of metal sulphide based photocatalysts have much attention in environmental remediation due to utilization of wide spectrum range. In present paper, the photocatalytic activity of NiS and NiS-CNTs (carbon nanotubes) nanocomposite has been investigated. The hydrothermal technique was used for synthesis of NiS and NiS/CNTs nanocomposite. Structural elucidation of NiS and NiS/CNTs nanocomposite was conducted by X-ray diffraction (XRD) and Fourier transform infra-red (FTIR) techniques. These characterization techniques verified the formation and purity of samples as extra peaks of impurities were not observed in the obtained data. Scherer formula was used to examine the crystallite size of NiS NPs and NiS/CNTs reported that 9.5 nm and 10.2 nm are sizes of NiS and NiS/CNTs respectively. Scanning electron microscopic (SEM) analysis revealed the reduction in the aggregation of NiS and improved the surface area to assist the redox reactions due to presence of CNTs. Current-voltage (I–V) measurements studied the electrical behaviour of photocatalysts. Optical measurements of synthesized samples were analysed by UV–Visible spectrophotometry. The improvement in bandgap energy of nanocomposite was main reason of excellent photocatalytic activity. About 96% degradation of methylene blue was recorded via NiS/CNTs nanocomposite within 50 min. Photocatalytic performance of nanocomposite is faster than individual metal sulphide due to production of more free radicals, Ni–S–C bond development, surface defects and availability of more reaction sites. These features improved the photocatalytic activity of NiS/CNTs and provide an evidence to use carbon nanotubes for the formation of metal sulphide nanocomposites. Antibacterial property of sample was investigated by four Gram negative bacteria (Proteus vulgaris, Klebsiella pneumonia, Escherichia coli and Pseudomonas aeruginosa) and one Gram positive bacteria (Staphylococcus aureus) at different concentrations using disc diffusion method. The possible mechanism for degradation of Methylene blue under UV–Visible illuminations has been discussed. The upgraded degradation of methylene blue by NiS/CNTs nanocomposite supported that it is promising material for treatment of wastewater.     

Novel flower-like hyperbranched ZnTe nanostructures prepared via catalyst-assisted vacuum thermal evaporation

Novel flower-like hyperbranched ZnTe nanostructures were prepared by catalyst-assisted vacuum thermal evaporation method. Various analysis techniques including X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM) and selected area electronic diffraction (SAED) were conducted on the as-prepared products. The XRD analysis demonstrates the ZnTe nanostructures are high pure single crystalline of zinc-blende structure. These novel ZnTe nanostructures are grown by a combination of the vapor–liquid–solid (VLS) growth mechanism and screw-dislocation-driven mechanism. The nanostructures formed by VLS mechanism have smaller sizes of several to ten micrometers and secondary branches with diameters of 100 nm. The nanostructures combined VLS and screw-dislocation-driven growth mechanism have a diagonal size of 40 µm and they consist of quartic branches, among which the secondary branches are spiral. The stems of the nanostructures with no-spiral secondary branches and their branches of the two kinds of nanostructures are all capped by a spherical catalyst particle, which is an indication of VLS growth mechanism. These as-prepared ZnTe nanostructures perhaps have potential applications in optoelectronics due to their unique geometric configurations.     

Evidence for growth mechanism and helix-spiral cone structure of stacked-cup carbon nanofibers

New evidence for the structure of Ni-catalyzed stacked-cup carbon nanofibers (CNFs) has been found. This type of carbon nanofiber exhibits a wide hollow core as well as a large diameter (between 40 and 140 nm). The fibers have been produced by the floating catalyst method using natural gas as carbon feedstock, a sulfur compound, and a nickel catalyst. It was found that the catalytic particles are heterogeneous with two different parts: one composed of metallic Ni, which is the catalytically active portion of the particle, and another composed of NiS, which allows for the hollow nanofiber structure. The hollow core of the fibers has similar dimensions to the NiS volume of the particle and the graphitic layers grow from the rear nickel region of the particle. Nevertheless, the NiS component seems to be indispensable in producing the helix-spiral formation of the graphitic structure, as clearly shown by the TEM studies.     

花状NiO纳米片自组装体的制备与表征

以硝酸镍、尿素为原料,在醇-水介质中,85℃恒温条件下,用均匀沉淀法制备出花状纳米片自组装结构Ni(OH)_2沉淀,该沉淀经400℃煅烧制得具有花状形貌的NiO纳米片自组装体.采用X射线衍射、扫描电镜、透射电镜、Fourier变换红外光谱、Brunauer-Ennett-Teller(BET)比表面积方法对粉体进行表征.研究表明:该NiO粉体为六方结构,其纳米片尺寸约为2μm × 3μm,厚度约为100nm,曲面间隙约为0.8μm,具有微孔结构.BET法测得粉体的比表面积为108.66m~2/g,制得的粉体具有明显的纳米效应,Ni-O键振动峰值(403.6cm~(-1))较非纳米颗粒(487.1 cm~(-1))蓝移了84.5cm~(-1),乙醇对花状结构NiO纳米片自组装体的形成具有重要作用.分析了花状NiO纳米片自组装体的形成机理.     

Growth and optical properties of hierarchical flower-like ZnO nanostructures

The integration of low dimensions nanoscale building blocks into 3D architectures has attracted great scientific attention. We have obtained the novel hierarchical flower-like ZnO nanostructures self-assembled by nanorods via a facile hydrothermal method. The as-synthesized samples were characterized with various technologies. The field emission scanning electron microscope (FESEM) images indicated that hydroxide ions play a significant role on the formation of hierarchical flower-like ZnO nanostructures. The X-ray diffraction (XRD) result proved that the nanocrystals were well crystallized hexagonal wurtzite structure. A possible growth mechanism of the nanostructures was proposed based on the effects of hydroxide ions. And the TEM imagines provided some important evidence for the proposed growth mechanism. UV–vis adsorption and photoluminescence (PL) spectra results indicated that the obtained ZnO nanostructurs have a good optical-absorption and photoluminescence property. The as-synthesized ZnO nanostructures exhibited superior photocatalytic performance, which was higher than that of commercially available ZnO.