水热法制备纳米片组装氧化铜微球的研究

本论文制备了由纳米片组装的粒径3-5μm的球形CuO,并通过XRD、SEM、TEM、TPR和氮气吸附对其结构和性能进行了表征。结果表明：CuO微球为单斜对称晶型,且由CuO纳米片组装而成,比表面积为18．5m2／g,BJH-PSD曲线中最大孔分布在29．6nm。     

纳米AgCl粉体的室温固相制备技术研究

以KCl和AgNO3为原料,通过加入分散剂并采用其对产物层层包覆的方式对传统的室温固相反应进行改进,制备出纳米AgCl粉末,并通过TEM及XRD对颗粒进行了测试表征.结果表明:通过"包覆"式固相反应制备工艺获得的AgCl呈规则球形,立方晶型结构,分散性高,平均粒径约20 nm,较传统方法制备的颗粒更加均匀细小.     

纳米晶TiO2的形貌对其荧光性能影响的研究

利用溶剂热合成法成功制备出了形貌为准球形、棒形、球棒混合型和菱形,粒径在50nm以下、尺寸均一的锐钛矿型TiO2纳米晶,对合成出的纳米晶TiO2用荧光光谱,紫外/可见光吸收光谱进行光学性能表征,结果表明,TiO2纳米晶在330 nm的激发光下,分别在345 nm、363nm、380nm和402 nm处存在4个发光峰位。在实验中,首次发现和证实了理论计算出的锐钛矿型TiO2纳米晶的两种直接跃迁发光,分别对应为X（1b）→X（2b）（345 nm）和X（1b）→X（1a）（363 nm）,主要因为油酸改变了TiO2纳米晶的{001}晶面族晶面的表面态。TiO2纳米晶的紫外吸收峰位于229 nm,且与其形貌无关;禁带宽度的计算值接近其理论值3.2 eV。     

热压烧结纳米晶铜粉性能的研究

利用置换反应制得平均粒径47nm的纳米晶铜粉并将其进行真空热压烧结.作为对比,将市售电解铜粉在相同条件下制得烧结试样.对试样的微观结构和性能进行了研究和分析.研究发现,由纳米晶铜粉制得的烧结试样,与电解铜粉的具有相同的致密度,弯曲强度提高21%,维氏硬度提高83%,电阻率提高50%.     

化学沉淀法制备电极用纳米β-Ni(OH)_2粉体材料

通过化学沉淀法成功制备了电极用纳米B-氢氧化镍粉体。用TEM及XRD时样品进行分析,结果表明,所得产物为球形或椭球形,粒径在2～20nm之间,平均粒径为10nm左右,晶型为β型的纳米晶粒。实验得出了制备纳米氢氧化镍粉体的温度、氨水浓度与pH值的最佳参数。     

四氧化三铁纳米粉在水溶液中分散稳定性的研究

采用液相共沉淀法制备了Fe3O4粒子,选用柠檬酸铵、白蛋白、PEG200和柠檬酸等作为分散剂,对Fe3O4纳米粉体进行表面修饰和改性,研究了分散剂种类、添加量及粉体含量等对Fe3O4纳米粉稳定性的影响.研究结果表明,白蛋白和柠檬酸铵是水溶液中纳米粉体很好的分散剂;电解质柠檬酸铵作为分散剂时,溶液分散处理都能达到很好的稳定效果;用白蛋白分散时,最佳工艺条件为:纳米Fe3O4粉体含量为40mL标准溶液/100mL溶液,白蛋白添加量为1.6mL.最后采用HRTEM、FT-IR等对其结构和包裹性能进行表征,结果表明,纳米粒子表面包覆了柠檬酸铵,柠檬酸铵包覆的Fe3O4纳米粒子基本呈球形,单个晶粒粒径约为10nm,制得的磁性液体分散稳定效果很好.     

铁基多元纳米合金的室温固相法制备及性能

以过渡金属氯化物和硼氢化钾为原料,用PVP作分散剂,通过室温固相化学反应法制备了FeNi-Co-B、Fe-Ni-Cu-B两种多元纳米合金,并用电感耦合等离子发射光谱、X射线粉末衍射、透射电镜、热分析等手段对产物进行了表征。结果表明,通过室温固相法得到的Fe-Ni-Co-B多元纳米合金为非晶态晶须,其晶须长100~200nm,直径为2~4nm;而Fe-Ni-CuB多元纳米合金为平均粒径约20nm的球形颗粒。同时研究了两种铁基多元纳米合金对高氯酸铵热分解的催化作用,发现两种合金对高氯酸铵降低高温分解温度和提高分解热有明显作用。     

微波辅助共沉淀法制备NiZnCu铁氧体纳米粉体研究

以硝酸铁、硝酸铜、硝酸镍和硝酸锌为原料,采用微波辅助共沉淀法制备了NiZnCu铁氧体纳米粉体,研究了微波的引入对纳米粉体制备的影响,通过XRD、TG-DTG、激光粒度分析和TEM表征了粉体的结晶性能,热性能,粒度以及粉体的形貌.研究表明,微波的引入可以明显加速晶化反应的进行,在较短时间内制得的纳米晶发育好于同温度下传统热处理方式制得的NiZnCu铁氧体纳米晶.研究表明,通过15min的微波辅助加热,可制得粒径在10nm左右的NiZnCu铁氧体纳米晶.     

ZnO纳米粒子沉积MoS_2纳米片的组装及其光催化性能

通过室温搅拌混合过程,将前驱物ZnO纳米粒子悬浊液与MoS_2纳米片悬浊液按一定比例直接混合,制得ZnO纳米粒子沉积在MoS_2纳米片表面上的纳米复合材料。使用各种测试技术对这种复合材料进行了表征,结果表明,ZnO纳米粒子呈六方晶相,形貌由两部分构成,一部分呈纳米棒状,直径主要在2~9nm之间;另一部分呈近球形,粒径主要在3~10nm之间;MoS_2纳米片是2H型晶相,呈单层或少层。由于在光照下ZnO上的电子传递到MoS_2纳米片表面,ZnO在510nm附近的激子发光带强度明显减弱。对罗丹明B的光催化性能测试结果证实,在可见光照射下,复合材料的光催化活性与纯MoS_2纳米片基本相当;而在紫外光照射下,复合材料的光催化活性最高,在光照160min后,其光降解率可达92%。     

单分散纳米二氧化硅微球的制备与表征

采用溶胶一凝胶法制备了粒径为480～500nm的单分散球形纳米二氧化硅微球,研究了分散剂和氨水用量对纳米粒径的影响.利用激光粒度仪、傅里叶红外光谱仪和扫描电镜等对纳米颗粒的粒径、结构和形貌等特性进行了表征.结果表明,氨水用量增加,则粒径和团聚程度增大;分散剂用量增加,粒径分布范围相对较窄,但随着分散剂用量的增加粒径增大,并出现一定程度的团聚.     

New data on the composition of the crystalline phases in the Cu-Te-O system

With the help of X-ray microanalysis and X-ray analysis new data about the composition of the crystal phase in the Cu-Te-O system have been obtained. The data from the X-ray microanalysis were treated by the method of the number of the oxygen atoms, and the chemical formulae of the crystal phases were evaluated. The following phases were established: the real composition of the stoichiometric composition 2TeO₂ · CuO corresponds to the crystalline phase 5TeO₂ · 2CuO with variable composition in the limits from 7TeO₂ · 3CuO to 11TeO₂ 4CuO with X-ray data presented as 2TeO₂ · CuO phase. The composition TeO₂ · CuO corresponds to a crystalline phase from TeO₂ · CuO to 6TeO₂ · 5CuO. From a melt of TeO₂ · CuO composition overcooled and crystallized is formed 5CuO · 2TeO₂. At a given composition 3CuO · TeO₂ or 3CuO · TeO₃ corresponds to the crystalline phase 5CuO · 2TeO₃ with two polymorphic modifications — cubic and tetragonal. The X-ray data obtained in the present investigation and those in literature are accepted to correspond to two polymorphic forms.     

Conductometric chemical sensor based on individual CuO nanowires

CuO nanowires with high crystalline quality are synthesized via a simple thermal oxidation method. Charge conduction on individual nanowires under a transverse electric field exhibits an intrinsic p-type semiconducting behavior. Variations in signal transducer in different chemical gas environments are measured on individual CuO nanowire field effect transistors. They demonstrate good performance to both NO(2) and ethanol gasses. In particular, the nanowire chemical sensor reveals a reverse response to ethanol vapor under temperature variation. Experimental results and first-principles calculations indicate that ethanol is oxidized in air at high temperature, resulting in the production of CO(2) and H(2)O. The strong H(2)O adsorption leads to the reversal behavior, due to the electron transfer from H(2)O molecules to the CuO surface.     

Development and characterization of nano‐crystalline cellulose incorporated poly(lactic acid) composite films

Development of nano‐cellulose has fascinated a substantial attention for last few decades because of their exceptional and potentially useful features. Herein, nano‐crystalline cellulose has successfully been prepared from local cotton yarn via acid hydrolysis. Both X‐ray diffraction and scanning electron microscopy showed improvement in crystallinity of nano‐crystalline cellulose on acid hydrolysis of cotton yarn. The prepared nano‐crystalline cellulose has been used for the fabrication of poly(lactic acid) composite films using solution casting approach. The prepared composite films were characterized using advanced analytical techniques. The differential scanning calorimetry analysis, moreover, showed that on incorporating nano‐crystalline cellulose in the poly(lactic acid) matrix, glass transition temperature increased; whereas, melting temperature and cold crystallization temperature decreased. The decreasing value of crystallization temperature indicated an enhancement in chain mobility of composite films. The mechanical analysis showed that the composite films were stronger and more flexible than the pure poly(lactic acid) films.     

Bulk synthesis of amorphous and nano‐crystalline materials by spray forming

Bulk amorphous and nano‐crystalline metallic materials have been observed to possess excellent mechanical and physical properties. The conventional process routes, to synthesize such materials, are restricted by their ability to achieve rapid solidification, which limits the dimensions of the materials produced. In the last 10–12 years, spray forming has been employed to avoid these limitations by using its capability of layer by layer deposition of undercooled droplets. The current literature indicates that the opportunities provided by this process can be effectively utilized to produce bulk materials in a single step. In this paper, an attempt has been made to bring out the developments in the synthesis of bulk amorphous and/or nano‐crystalline materials by spray forming. The effect of process parameters, droplet size distribution in the atomized spray, the thermal conditions of droplets prior to deposition and the deposition surface conditions have been discussed. It has been demonstrate that a layer by layer deposition of undercooled droplets of glass forming alloys on a relatively cold deposition surface is the suitable condition to achieve bulk amorphous/nano‐crystalline materials.     

纳米Cu对HTPB-AP推进剂性能的影响

为研究纳米铜Cu对丁羟推进剂性能的影响,制备了含纳米Cu的推进剂,作为比较,同时制备了含有纳米CuO的推进剂和空白推进剂试样。采用SEM和TG-DSC表征推进剂的形貌和热性能,采用靶线法测试推进剂的燃速,并拍摄推进剂的燃烧火焰。TG-DSC结果表明,纳米Cu和纳米CuO主要影响AP的高温热分解阶段,但是纳米CuO比纳米Cu对推进剂的热分解具有更好的催化作用。纳米Cu可使AP的终止热分解温度降低67.0 ℃,使推进剂的终止热分解温度降低24.7 ℃。燃速测试结果表明,纳米Cu和纳米CuO均可提高推进剂的燃速,但是纳米Cu对推进剂燃速的改善效果更显著。加入纳米Cu和纳米CuO后,推进剂在燃烧过程中均出现蓝色火焰。     

氧化铜纳米粉体的制备新方法

首次以铝箔代替恒电位/电流仪惰性电极作为基体,采用辅助电极电沉积法成功制备了氧化铜纳米颗粒。用X射线衍射仪和透射电子显微镜对所制备的纳米粉体进行了表征,结果表明:氧化铜纳米颗粒为球形,粒径为50nm左右,颗粒大小均匀,形态稳定。并且与氧化还原法和研究电极电沉积法进行了比较。     

Intracellular Uptake and Toxicity of Ag and CuO Nanoparticles: A Comparison Between Nanoparticles and their Corresponding Metal Ions

An increased understanding of nanoparticle toxicity and its impact on human health is essential to enable a safe use of nanoparticles in our society. The aim of this study is to investigate the role of a Trojan horse type mechanism for the toxicity of Ag‐nano and CuO‐nano particles and their corresponding metal ionic species (using CuCl₂ and AgNO₃), i.e., the importance of the solid particle to mediate cellular uptake and subsequent release of toxic species inside the cell. The human lung cell lines A549 and BEAS‐2B are used and cell death/membrane integrity and DNA damage are investigated by means of trypan blue staining and the comet assay, respectively. Chemical analysis of the cellular dose of copper and silver is performed using atomic absorption spectroscopy. Furthermore, transmission electron microscopy, laser scanning confocal microscopy, and confocal Raman microscopy are employed to study cellular uptake and particle‐cell interactions. The results confirm a high uptake of CuO‐nano and Ag‐nano compared to no, or low, uptake of the soluble salts. CuO‐nano induces both cell death and DNA damage whereas CuCl₂ induces no toxicity. The opposite is observed for silver, where Ag‐nano does not cause any toxicity, whereas AgNO₃ induces a high level of cell death. In conclusion: CuO‐nano toxicity is predominantly mediated by intracellular uptake and subsequent release of copper ions, whereas no toxicity is observed for Ag‐nano due to low release of silver ions within short time periods.     

In Situ Synthesis of CuO and Cu Nanostructures with Promising Electrochemical and Wettability Properties

A strategy is presented for the in situ synthesis of single crystalline CuO nanorods and 3D CuO nanostructures, ultra‐long Cu nanowires and Cu nanoparticles at relatively low temperature onto various substrates (Si, SiO₂, ITO, FTO, porous nickel, carbon cotton, etc.) by one‐step thermal heating of copper foam in static air and inert gas, respectively. The density, particle sizes and morphologies of the synthesized nanostructures can be effectively controlled by simply tailoring the experimental parameters. A compressive stress based and subsequent structural rearrangements mechanism is proposed to explain the formation of the nanostructures. The as‐prepared CuO nanostructures demonstrate promising electrochemical properties as the anode materials in lithium‐ion batteries and also reversible wettability. Moreover, this strategy can be used to conveniently integrate these nanostructures with other nanostructures (ZnO nanorods, Co₃O₄ nanowires and nanowalls, TiO₂ nanotubes, and Si nanowires) to achieve various hybrid hierarchical (CuO‐ZnO, CuO‐Co₃O₄, CuO‐TiO₂, CuO‐Si) nanocomposites with promising properties. This strategy has the potential to provide the nano society with a general way to achieve a variety of nanostructures.     

Particle-size effect of CuO and ZnO on biogas and methane production during anaerobic digestion

The effects of bulk- and nano-sized CuO and ZnO particles on biogas and methane production during anaerobic digestion of cattle manure were studied for a period of 14 days at 36 °C using the ISO 13641-2 guidelines. Biogas production was severely affected at concentrations of bulk and nanoparticles over 120 and 15 mg/L for CuO and 240 and 120 mg/L for ZnO, respectively. EC50 concentrations for methane inhibition were estimated to be 129 mg Cu/L for bulk CuO, 10.7 mg Cu/L for nano CuO, 101 mg Zn/L for bulk ZnO and 57.4 mg Zn/L for nano ZnO. The solubility of CuO nanoparticles in the reaction mixture was observed after 14 days of incubation and was significantly higher than the levels observed for ZnO. These results are of significant importance, as it is the first time that the effects of metal oxide particle size on biogas and methane production have been studied.     

New insights on physico-chemical transformations of ZnO: From clustered multipods to single crystalline nanoplates

Physico-chemical transformations of ZnO have been investigated in low temperature reflux reactions involving zinc nitrate, hexamethylene tetramine and cetyl trimethyl ammonium bromide. The stability features of various ZnO micro/nano structures were systematically examined from 4 to 60 h. The study showed the formation and transformation of multidimensional ZnO structures such as multipods, microtubes, microplates, nanoplates, nanoflowers, nanoblades and diffused nano networked structures including single crystalline nanoplates in a simple reflux synthesis. The crystalline nature, phase purity, associated structural features and surface characteristics were studied using powder X-ray, Raman, SEM, TEM, AFM, FT-IR, XPS and TG analytical techniques and the results were discussed. The kinetics involved in the evolution of ZnO structures and % yield of the ZnO products has also been studied and a possible growth mechanism is proposed on the basis of time-triggered transformations. The inherent anisotropic nature of ZnO as well as the change in chemical environment over the time of reflux is found to control the growth and evolution of diverse ZnO morphologies.