壳聚糖为负载的纳米硒的制备

报道了以壳聚糖为负载,通过还原型谷胱甘肽和亚硒酸钠的反应制备纳米硒的方法.采用光谱法、扫描电镜和X射线衍射法对产物进行了表征,研究了反应时间、反应物浓度、洗涤溶剂等对产物颗粒大小、形貌的影响.     

金属氧化物纳米粒子的制备与表征

在乙二醇-水体系中,以CuSO4和尿素为反应物制备了分散性较好的CuO纳米粒子.用粉末X-射线衍射(XRD)和扫描电子显微镜(SEM)表征了样品的物相和微观形貌.结果表明,所得样品为单斜相的CuO纳米粒子,颗粒均匀,粒径约30 nm.讨论了溶剂组成、反应物浓度等实验条件对样品形态的影响.并用此方法制备了粒度均匀的ZnO纳米粒子和MnO2纳米粒子.     

PVK纳米纤维的电纺制备及表征

以甲苯和N,N二甲基甲酰胺(DMF)混合液为溶剂,采用静电纺丝法制备了PVK纳米纤维;通过扫描电子显微镜(SEM)对纤维形貌进行了表征,并进一步研究了浓度、纺丝电压及纺丝距离等实验条件对纤维形貌的影响;采用荧光发射光谱及荧光显微镜对电纺纤维进行了光学表征.结果表明:纤维直径随着纺丝溶液质量分数的增加而增大;随着电压的增加先减小后增加;随着纺丝距离的增加而减小.荧光显微镜分析表明:PVK电纺纤维在紫外光照下发蓝紫光.荧光光谱分析表明:与PVK薄膜比较,PVK电纺纤维在437 nm处出现一个新的发射峰.     

基片表面朝向对ZnO纳米线生长机理的影响

采用热蒸发ZnO粉末法,以金膜为催化剂,在两片表面分别朝上和朝下的Si(100)基片上生长ZnO纳米线(样品分别标为1#和2#)。X射线衍射(XRD)图谱上只存在ZnO的(002)衍射峰,说明ZnO纳米线沿(001)择优取向。通过扫描电子显微镜(SEM)表征发现,ZnO纳米线整齐排列在Si基片上,直径在100nm左右,平均长度为4mm。通过分析得出,两种基片上生长的ZnO纳米线的生长机理是不相同的:1#样品,在基片表面上先生长ZnO薄膜,再在薄膜上生长ZnO纳米线;2#样品,ZnO纳米线直接外延生长在基片表面。结果显示基片表面的朝向影响ZnO纳米线的生长机理。     

宏观树枝状铜纳米线的制备及分形学研究

为了进一步揭示固态离子学方法制备铜纳米线的生长机理,选取具有高离子电导率的快离子导体Rb_4Cu_(16)Cl_(13)I_7薄膜,利用固态离子学方法在外加恒定电流3μA作用下,制备厘米级铜纳米线.采用扫描电子显微镜对其微观形貌进行了表征和分析,利用能量色散光谱仪确定纳米线的化学成分.结果表明:制备的铜纳米线呈现宏观树枝状结构,在靠近阴极位置整齐排布,长度约为2 mm,且排布比较紧密,部分纳米线在生长过程中出现分形生长,最长分支长度约为1 cm,排布比较稀疏;铜纳米线呈长程无序短程有序,直径分布范围为90~100 nm,纳米线表面铜纳米颗粒直径分布范围为10~20 nm,树枝状铜纳米线的分形维数为1.35,说明树枝状铜纳米线较少,铜纳米线的生长机理分析表明,树枝状结构的出现与纳米线"顶端生长优势"有关.     

ZnS微米球的制备和发光性能

以Zn(AC)2·2H2O和(NH2)2CS为原料.乙醇溶液为溶剂,通过溶剂热法成功合成TZnS微球.使用X射线衍射仪(XRD)、扫描电子显微镜(SEM)、能量分散谱仪(EDS)和荧光光谱仪(FS)对ZnS微球进行表征.结果表明,实验制备了平均粒径4 μm,高分散的立方晶型ZnS微球,并在紫外光激发下发射位于501 nm的绿光.     

TiO_2纳米线/Bi_2WO_6催化剂制备及影响因素探究

为制备具有可见光响应的高效光催化剂,采用水热法制备了点-线型形貌的TiO_2纳米线/Bi_2WO_6复合催化剂,考查了钛源、水热温度、溶剂、复合配比等制备因素对复合催化剂形貌的影响,并采用X射线衍射(XRD)、紫外-可见吸收光谱(UV-Vis)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)等方法进行表征.结果表明:采用钛酸丁酯制备的TiO_2纳米线为锐钛矿相且结晶度良好;水热温度为180℃,溶剂为乙二醇,TiO_2纳米线复合配比为50%(质量分数)时所制备的TiO_2纳米线/Bi_2WO_6复合催化剂点-线形貌最优;TiO_2纳米线复合窄带隙半导体Bi_2WO_6明显拓宽了光谱响应范围,复合催化剂的禁带宽度达Eg=2.70 e V.     

聚二甲基硅氧烷裂解法碳化硅纳米线的制备及表征

以聚二甲基硅氧烷和金属硅粉为反应原料,在专用管式炉中成功实现了碳化硅纳米线的生长制备。利用X射线衍射仪、扫描电子显微镜、傅里叶变换红外光谱仪和透射电子显微镜对制备的产物进行性能表征,并对影响碳化硅纳米线生长的因素进行探究讨论。研究结果显示:所获得的浅绿色纤维产物为闪锌矿结构单晶碳化硅纳米线,纳米线直径约30nm,长度可达几厘米。在此反应体系中,聚二甲基硅氧烷注射速率和高温保温时间对纳米线的生长有着重要作用,在聚二甲基硅氧烷注射速率为0.4~0.5mL/min,高温保温时间为2.0h的条件下,能成功实现优质碳化硅纳米线的制备。     

基板法催化生长纳米碳纤维薄膜

以乙炔(C2H2)为碳源,铜溶胶和硫化铜为催化剂前躯体,采用化学气相沉积法(CVD)在玻璃基板上生长纳米碳纤维薄膜。通过扫描电子显微镜(SEM)、透射电子显微镜(TEM)和X射线衍射仪(XRD)对产物的形貌与结构进行了表征。结果表明:在反应温度为350℃时,制备出了纤维直径为100～200nm,厚度为3～20μm的均匀的纳米碳纤维薄膜;随着反应温度升高或者反应时间的延长,纳米碳纤维薄膜的膜厚增厚。     

电化学模板法制备Pt-WO3纳米线有序阵列

通过恒电势共沉积的方法,用银作为导电基底的多孔阳极氧化铝膜(Al2O3／Ag)为模板制备了Pt-WO3纳米线有序阵列。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)和能量色散X射线分析(EDAX)对纳米线进行了表征。结果表明,纳米线呈直立状态,直径约为30nm,纳米线中Pt和w的质量比为m(Pt)：m(w)=19．6：1,原子的量比为,n(Pt)：n(W)=18．5：1。这种Pt-WO3纳米线有序阵列具有很大的比表面积,可用于有机小分子的电催化氧化。     

钛酸盐纳米线对水中Fe(Ⅱ)和Mn(Ⅱ)的吸附

以钛酸四丁酯为钛源,采用水热法制备钛酸盐纳米线.利用X射线衍射(XRD)、扫描电镜(SEM)和透射电镜(TEM)对钛酸盐纳米线的物化性能进行表征.通过对水中Fe(Ⅱ)和Mn(Ⅱ)的静态吸附试验,考察钛酸盐纳米线的吸附活性.结果表明,水热法制备的钛酸盐纳米线直径分布在50～400 nm,长度可达几微米甚至几十微米.在温度为25℃、溶液pH为6.68的条件下,钛酸盐纳米线对水中Fe(Ⅱ)和Mn(Ⅱ)的饱和吸附量分别达到39.89和34.67 mg/g,吸附过程较好地符合Freundlich吸附等温线.采用Lagergren一级吸附动力学模型能够较好地描述钛酸盐纳米线的吸附动力学.此外,在本实验条件下,钛酸盐纳米线对水中Fe(Ⅱ)和Mn(Ⅱ)的吸附去除率随溶液pH值及吸附剂投加量的增大而增大.     

银纳米线的制备及其对电化学发光催化研究

采用水热法,在反应体系中加入微量的CuCl2作为去氧剂,以AgNO3为前驱物,聚乙烯吡咯烷酮(PVP)为稳定剂和结构导向剂,乙二醇为还原剂和溶剂制备银纳米线.研究了反应温度、反应时间及CuCl2浓度对产物微观形貌的影响.通过X-射线衍射(XRD)、扫描电子显微镜(SEM)等检测手段表征了其结构和性能.同时,将所制得的银纳米线作为联吡啶钌[Ru(bpy)2+3]电化学发光(ECL)的工作电极对其催化机理进行研究.结果表明:在反应温度为165℃、反应时间为1h、CuCl2浓度为4 mmol/L时制备出了具有面心立方结构的,长度为13 μm,长径比约为75的银纳米线;与普通银丝电极相比,由于具有较高的比表面积和较独特的催化特性,银纳米线电极更适合作为Ru(bpy)2+3 ECL的工作电极.     

三氧化钼纳米带的简易合成与表征

在不添加表面活性剂,无模板的情况下,以钼粉和双氧水为原料,采用90℃水浴的方法制备三氧化钼纳米带。用X-射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM)对产物进行表征。结果表明,反应产物均为三氧化钼纳米带,且纳米带尺寸均匀,宽度为80～100nm,厚度为20nm,长度为5～30μm。研究还发现,合成条件如反应时间,反应介质对产物的形貌有一定影响。     

钼掺杂五氧化二钒纳米带的制备及表征

分别以金属Mo粉为钼源、V2O5为钒源和以MoO3为钼源、NH4VO3为钒源,通过低温水热法合成了不同形貌的钼掺杂V2O5纳米结构。用X-射线衍射(XRD)、扫描电子显微镜(SEM)和能谱(EDS)对产物进行表征。结果表明,反应产物均为正交V2O5纳米带,且纳米带的尺寸均匀,宽度100~400 nm,厚度10~40 nm,长度可达到几十微米。研究还发现它们的掺杂量是不同的,分别为3%和2.1%。     

Preparation and Enhanced Daylight-Induced Photo-Catalytic Activity of Transparent C-Doped TiO_2 Thin Films

The transparent C-doped TiO2 nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photocatalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO2 films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Hydrothermal synthesis of β-FeOOH with different morphologies using NaH2PO4 as structural modifier

Different morphologies of β-FeOOH were prepared by hydrothermal synthesis using NaH2PO4 as structural modifier. The rod-shaped, straw-like and flower-like products could be controllably obtained. The as-obtained products were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and Ultraviolet-visible (UV-Vis) absorption spectroscopy. The experimental results show that the morphology manipulation could be achieved by adding different amounts of NaH2PO4. XRD pattern indicates that the as-prepared sample is the pure tetragonal phase of β-FeOOH. UV-Vis absorption spectra of the products are affected by their morphologies, which shows that both the rod-shaped and straw-like β-FeOOH have outstanding absorption ability on the whole UV area (200-400 nm), which will have vast application prospects in UV protection.     

Preparation and enhanced daylight-induced photo-catalytic activity of transparent C-Doped TiO<Subscript>2</Subscript> thin films

The transparent C-doped TiO₂ nanostructure films were fabricated on the silicate glass substrates by sol-gel spin-coated method. The as-prepared films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-visible absorption spectra (UV-vis) and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was evaluated via the photo-catalytic oxidation of methylene blue in aqueous under daylight irradiation at room temperature. The results show that the daylight-induced photocatalytic activities of the as-prepared films are improved by the C-doping. The calcination temperatures significantly affect the morphology, microstructure and photocatalytic activity of the as-prepared samples. At 723 K, the C-doped TiO₂ films exhibit the highest photocatalytic activity due to the synergetic effects of good crystallization, appropriate oxygen vacancies and strong absorption in the near UV and visible-light region.     

Characterization of ultrafine copper powder prepared by novel electrodeposition method

The auto-evolved ultrafine copper powders were synthesized via a novel electrodeposition route performed by ultrasonic dispersion of the electrolyte. The properties of the samples obtained were characterized by X-ray powder diffractometry (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and laser size distribution analyzer (SL) respectively. The formation mechanisms of the powders and the efficiency of the elctrodeposition were discussed. The results show that the as-prepared powders are high-purity copper nanoparticles with the fcc structure taking a mixture of fishbone-like and irregular shapes. When the concentration of Cu²⁺ increases from 0.03 to 0.09 mol/L, the average size of copper particles increases from 0.92 to 1.80 μm, and current efficiency of electrodeposition linearly changes from 66.5% to 91.3%.     

Hydrothermal synthesis and photoluminescence behavior of CeO2 nanowires with the aid of surfactant PVP

Well-crystalline CeO_2 nanowires were prepared via a surfactant-assisted hydrothermal process.Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters.The as-obtained products were characterized by X-ray diffraction (XRD),high-resolution transmission electron microscopy(HRTEM),and field emission scanning electron microscopy(FESEM).The results show that single crystal CeO_2 nanowires with high yield and good uniformity can be obtained hydrothermally at 180℃...     

<Emphasis Type="Italic">In-situ</Emphasis> growth and photoluminescence of β-Ga<Subscript>2</Subscript>O<Subscript>3</Subscript> cone-like nanowires on the surface of Ga substrates

β-Ga₂O₃ cone-like nanowires have been in-situ grown on the surface of gallium grains and films by heating gallium substrates at 750–1000°C for 2 h in air. The controllable synthesis of β-Ga₂O₃ nanowires with different diameters and lengths was achieved by adjusting the heating temperature and time. The as-synthesized products were characterized by means of X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results showed that the β-Ga₂O₃ nanowires are single crystalline with a monoclinic structure and have a controllable diameter and length in the range of 30–100 nm and 0.5–1.5 μm, respectively. A possible mechanism was also proposed to account for the formation of β-Ga₂O₃ cone-like nanowires. Photoluminescence spectra of the β-Ga₂O₃ nanowires obtained at different temperatures were measured at room temperature, and a strong blue photoluminescence with peaks at 430 and 460 nm and a weak red photoluminescence with peak at 713 nm were observed. The blue light emission intensity decreases with increasing the reaction temperature, however, the red light emission intensity hardly changes. The blue and red light emissions originate from the recombination of an electron on an oxygen vacancy with a hole on a gallium-oxygen vacancy pair and the nitrogen dopants, etc., respectively. Supported by the National Natural Science Foundation of China (Grant No. 20573072) and Specialized Research Fund for the Doctoral Program of Higher Education of China (Grant No. 20060718010)