多枝CdS纳米晶粒的溶剂热法制备及光学性能研究

本文以溶剂热法在乙二醇溶剂里制备了小尺寸的多枝权CdS纳米晶粒,通过溶剂、硫源的选择,使其直径接近激子的玻尔半径(6nm),分析硫源和溶剂对CdS粒子晶体结构、形貌和尺寸的控制作用.对多枝权粒子的形成机理进行探讨,初步得到一种可能的两相共存的生长机制.光学性能的测试显示样品具有良好的量子尺寸效应和发光性能.选择合适的反应源和溶剂可调整半导体纳米粒子的形貌和尺寸,对制备满足不同应用需要的纳米结构,尤其是复杂形貌的纳米量子器件的应用具有重要的意义.     

复合体溶剂热分解低温一步合成NaInS_2纳米片刺球

以In(S2CNEt2)3复合体为前躯体,乙腈和油酸为溶剂和表面活性剂,采用复合体溶剂热分解法于200℃低温下一步合成了NaInS2微米球,通过调控油酸含量,成功制备出具有纳米片刺球结构的超结构NaInS2微米粒子。XRD和FE-SEM测试结果表明,所制备的NaInS2具有斜方六面体结构,物相单一,结晶良好。油酸对NaInS2微米球的微结构产生显著影响。少量油酸(5mL)的加入,对产物相组成和结晶性无明显作用,但可以使所得产物由实心微米球变为由级次粒子聚合而成的多孔微米球。当油酸含量高于10mL时,构成微米球的级次粒子发生明显的择优取向生长,形成具有极大孔隙度的纳米片刺球。漫反射光谱表明,所得NaInS2微米球对波长小于450nm的光均呈现很强的吸收,吸收边位于450nm。然而,纳米片刺球的吸收边位于400nm,蓝移达50nm。光致发光光谱证实,样品在245nm紫外光激发下,存在一个340~650nm的宽发光带,主峰位于340~450nm,源于电子带间跃迁。     

纳米TiO2/微米Cu复合粒子的制备及可见光活性

利用钛酸丁酯为原料,通过室温强迫水解的方法制备了具有可见光活性的纳米TiO2/微米Cu复合粒子.XPS分析表明复合粒子的表面存在Cu2 、Ti4 、Sn2 元素.场发射扫描电镜观察表明,4nm左右的TiO2颗粒覆盖在铜粉表面形成纳米/微米复合结构,利用空载实验获得表面包覆的TiO2颗粒样品,XRD结果显示TiO2颗粒呈现锐钛矿型,粒径约3.5nm.TG-DTA结果表明复合粒子与原始铜粉具有不同的高温氧化过程,表明TiO2与铜粉之间存在较强的相互作用,而不仅是简单的物理吸附.以甲基橙为模型化合物的降解实验显示出纳米TiO2/微米Cu复合粒子的可见光活性和可重复使用性,8h时照射后甲基橙的降解率达到97%,重复3次实验的降解率保持不变.     

Fe3O4纳米粒子的制备与超顺磁性

采用红外光谱、X射线衍射、透射电子显微镜和振动样品磁强计对用化学共沉淀法制备出的纳米Fe3O4粒子进行了形貌、结构及磁性能表征.其中,红外和XRD测试结果表明制备出的Fe3O4粒子的物态和晶相结构;透射电子显微镜照片表明制备出的纳米四氧化三铁成球性好,且大部分四氧化三铁粒子的粒径在10nm左右;磁化曲线表明制备出的Fe3O4粒子无剩磁和矫顽力,具有超顺磁性.并且,将制备出的纳米Fe3O4粒子和块状Fe3O4的磁性能进行对比,探讨了Fe3O4由块状的亚铁磁性向纳米级的超顺磁性转变的原因.     

不同形貌CuO纳米粒子的制备与性能

采用CuSO4.5H2O、Cu(NO3)2、(CH2)6N4和NaOH为原料,采用沉淀法分别制备纤维状CuO纳米粒子和纺锤状CuO纳米粒子,用透射电镜和X射线衍射仪对产物的大小﹑形貌和组成进行表征;按质量比为9∶1的比例将黑索金分别与纤维状CuO纳米粒子和纺锤状CuO纳米粒子混合,对样品进行热失重测试分析,根据黑索金热分解温度的变化来衡量催化剂的活性。结果表明,采用沉淀法制备CuO纳米粒子时,反应温度、终点pH值对产物形貌有显著影响;不同形貌的CuO纳米粒子对黑索金的分解催化作用效果不同。     

纳米Nd2O3/高氯酸铵复合粒子的制备及催化性能的研究

采用固相法制备出了纳米级的氧化钕颗粒.并用溶剂-非溶剂法制备出了Nd2O3/高氯酸铵(AP)复合粒子.XRD、SEM测试结果表明,氧化钕的平均粒径为50nm左右,复合粒子为微米级.对复合粒子中Nd2O3的催化热分解性能(DTA)的测试结果表明,Nd2O3/AP复合粒子可使AP的高温分解峰峰温下降88℃,低温分解峰消失.     

ZnO纳米带梳的制备及生长机理的研究

采用化学气相沉积(CVD)法成功制备出ZnO纳米带梳,实验过程不需要催化剂.X射线衍射仪(XRD)分析结果表明,ZnO纳米带梳为高度结晶的六方纤锌矿结构;利用扫描电子显微镜(SEM)观测,所制样品是由纳米带组成梳状形貌,纳米带梳的形成经过两个步骤:先通过VS机制形成微米带,而梳的齿通过自催化生长平行于(0001)极性面形成.对样品的光致荧光(PL)谱测量发现了位于～395nm和495nm处的室温光致发光峰.     

化学镀法制备纳米Cu/Al复合粉末

为了改善超细铝粉的表面易氧化问题和微米级铝粉对推进剂的热分解催化作用不明显现象,以对推进剂具有良好催化作用的纳米Cu包覆金属Al表面.采用化学镀铜法对微米级铝粉表面进行镀覆,制备出纳米Cu粒子在超细Al颗粒表面包覆完整的Al-Cu核壳式复合粉末,并利用正交实验优化镀液组分及镀覆工艺条件.利用XRD、SEM、EDX等仪器,对复合粉末的形貌、物相结构及表面成分进行分析,结果表明铝粉表面包覆一层致密的纳米铜层,这种纳米层是由粒度约为18.83nm的晶态析出的纳米铜组成.     

微米铜粉/纳米TiO_2复合粒子的低温制备及光吸收性能

利用仿生合成的方法在温和条件下制备了微米铜粉/纳米TiO2复合粒子.选择有机胺对Cu粉进行表面处理,XPS分析表明有机胺通过N原子与表面Cu2+络合形成功能层,在Cu粉表面引入NH2和OH等功能基团,对比实验证实功能基团能够诱导无机氧化物的仿生沉积.XRD结果表明铜粉表面包覆的纳米TiO2呈现锐钛矿晶型,漫反射光谱(DRS)分析表明,Cu粉经过有机胺处理后在716.5nm处出现了由Cu2+离子与N配位产生的弱吸收.复合粒子的光吸收性能介于TiO2和Cu粉之间,Cu负载后样品的光吸收阀值从397.5nm红移至448.9nm,红移的原因可归于Cu负载后TiO2导带下出现新能级,光生电子经过这些中间能级发生跃迁,所需激发能量降低至可见光范围.448.9nm处吸收边的存在表明复合粒子具备可见光催化活性.     

原位热硫化法制备Cu_3SnS_4纳米薄膜及其光学性质

采用化学水浴法(CBD)制备了Cu_3Sn纳米薄膜,通过原位热硫化法制备了Cu_3SnS_4纳米薄膜。分别采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)与X射线能谱仪(EDS)分析了样品的组成、结构与形貌。采用紫外-可见分光光度计(UV-Vis)测试了Cu_3SnS_4样品的光学性质。结果表明,样品物相纯净、形貌均一,Cu3Sn纳米薄膜由球形纳米颗粒组成,Cu_3SnS_4纳米薄膜由片状纳米颗粒组成,Cu_3SnS_4薄膜样品在紫外-可见光区有良好的吸收性质,其光学带隙为1.70eV,适合作为太阳能电池吸收层。     

Synthesis of γ-MnO2 single-crystalline nanobelts

High-quality γ-MnO₂ single-crystalline nanobelts have been synthesized by hydrothermal treatment of commercial γ-MnO₂ in NaOH aqueous solution. The products are characterized by X-ray diffractometer, scanning electron microscopy, and transmission electron microscopy. The width, thickness and lengths of γ-MnO₂ nanobelts are in the range of 80-100 nm, 10-20 nm, and several tens of micrometers, respectively. The influences of the reaction time, temperature, and medium on the morphologies of the resulting products have been investigated.     

ZnO准一维纳米结构生长形态的演化机理

利用气相生长系统,通过调控实验参数,制备了多种形貌的ZnO准一维结构,如纳米条带、[011-0]和[21-1-0]取向的单侧生齿的梳状纳米条带、微米尺度的梳状结构,由多节状六角棱柱和八角棱柱组装成的微米条带等.通过X射线衍射、扫描电子显微镜及其所加载的能谱分析和背散射电子衍射仪、高分辨透射电子显微镜等分析技术, 对其中具有代表性的介观结构进行了系统的形貌分析和细致的结构解析.分析出基本的结构单元及其复合体, 揭示了显微尺度下ZnO晶体的外形多样性以及其形态演化中的关联和规律,即ZnO纳米条带、梳状结构和多节状微米条带具有晶体结构上的同一性.     

Cu2ZnSnS4纳米颗粒及其薄膜的制备与表征

采用热注入法,在油胺(OLA)中合成出Cu2ZnSnS4(CZTS)纳米颗粒,并在玻璃衬底上制备了薄膜,研究了不同合成温度对纳米颗粒生成的影响.通过X射线衍射仪、拉曼光谱仪、透射电子显微镜、扫描电子显微镜、紫外可见分光光度计对所得纳米晶材料的结构与成分、颗粒大小与形貌、光吸收谱进行了测试分析.研究结果表明:采用热注入法的最佳合成温度在260℃左右,该温度下生成的多晶CZTS纳米颗粒尺寸约10 nm,分散性良好,光学禁带宽度约1.5 eV.     

Microwave-assisted synthesis of barium tungstate nanosheets and nanobelts by using polymer PVP micelle as templates

Single-crystal BaWO₄ nanosheets and nanobelts have been successfully synthesized by using polymer PVP micelle as templates in a reflux system under microwave irradiation. Our result shows that the concentration of PVP aqueous solutions played an important role in the formation of BaWO₄ crystal with different morphologies. The products were characterized by X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscopy (TEM) and electron diffraction (ED).     

Synthesis and field emission of single-crystalline copper vanadate nanobelts

Single-crystalline nanobelts of a nonstoichiometric compound Cu(1.55)V(2)O(6.55), with a thickness of 40-60?nm, width of 50-300?nm and length of several micrometers, have been synthesized on a large scale by a hydrothermal method. The structures and morphologies of the nanobelts were characterized by x-ray powder diffraction, x-ray photoelectron spectroscopy, scanning electron microscopy, transmission electron microscopy and high-resolution transmission electron microscopy. A probable growth mechanism has also been discussed. The nanobelts exhibit a turn-on field of 11.0?V?μm(-1), which is defined as the macroscopic field required to produce a current density of 10?μA?cm(-2). It is anticipated that the nanobelts can serve as a candidate material for future field emitters.     

pH-dependant structural and morphology evolution of Ni(OH)2 nanostructures and their morphology retention upon thermal annealing to NiO

Nickel hydroxide nanosheets, nanobelts and nanorods were prepared by hydrothermal treatment of the precipitates obtained at different pH values. The morphology and crystal structure of the products could be controlled simply by adjusting the pH value at precipitation. Interconnected nanosheets of hexagonal β-Ni(OH)₂ with thickness around 10–20 nm were formed at pH ∼ 11, whereas nanobelts with typical widths around 40–80 nm, and nanorods with diameters around 50–60 nm of phase pure α-Ni(OH)₂ containing intercalated sulphate ions were obtained in the pH range ∼9.5–8.5. Thermal annealing of the hydroxides at 500 °C yielded cubic phase NiO with morphologies similar to their hydroxide precursors. X-ray powder diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and energy dispersive X-ray (EDX) analysis were used to characterize the as-prepared products. The role of pH in controlling the phase and morphology of the products was discussed.     

无模板剂水热合成Bi12O17Cl2纳米带及其阻燃性能研究

以β-Bi2O3为原料,采用无模板剂水热法制备了Bi_(12)O_(17)Cl_2纳米带,利用X射线衍射(XRD)、扫描电镜(SEM)、透射电镜(TEM)和高分辨透射电镜(HRTEM)对其形貌和结构进行了表征并作为阻燃剂添加到聚氯乙烯(PVC)中评价其阻燃性能。结果表明,适宜的Bi/Cl物质的量比对水热合成Bi_(12)O_(17)Cl_2纳米带及其化学计量比影响显著,当Bi/Cl物质的量比为1∶2.5时,可得到分散性好、形貌均匀的Bi_(12)O_(17)Cl_2纳米带;改变Bi/Cl物质的量比,纳米带中Bi/Cl化学计量比从6∶1变成2.4∶1。初步探讨了Bi_(12)O_(17)Cl_2纳米带可能的生长机理,在水热反应过程中,Bi 3+与Cl-发生络合反应形成BiCln3-n络合物,从而合成Bi_(12)O_(17)Cl_2纳米带。     

不同结构形貌BiVO4的水热制备及可见光催化性能

采用水热法,无需添加剂,通过调控反应液pH值和反应温度制备了不同结构和形貌的BiVO4可见光催化剂.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、紫外可见漫反射(DRS)和低温氮吸附等手段对样品进行表征,结果显示:水热温度与反应液pH值对晶体结构有很大影响,180℃水热温度和酸性条件有利于单斜相的生成.反应液pH值对形貌也有很大影响,不同条件下得到了片状、立方状、棒状等不同形貌的BiVO4.同时以亚甲基蓝为降解对象,考察了所制备BiVO4的可见光催化活性.其中,pH值为2,反应液中制备的片状单斜相BiVO4具有最高的光催化活性(4 h达92.0%).此外,还考察了光催化剂用量、亚甲基蓝浓度和电子受体的存在对光催化过程的影响,结果表明:当催化剂用量为1.0 g/L,亚甲基蓝浓度为10 mg/L,KBrO3为电子受体时光催化效果最佳.     

Facile synthesis of MnV2O6 nanostructures with controlled morphologies

MnV₂O₆ nanostructures including nanorods, nanobelts, and nanosheets, have been synthesized by a facile hydrothermal reaction between Mn(CH₃COO)₂·4H₂O and commercial V₂O₅. The synthesized products are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The influences of synthetic parameters, such as, reaction time, temperature and medium, on the morphologies of the resulting products have been investigated. As the reaction temperatures increase from 120 °C to 180 °C, MnV₂O₆ nanorods and nanobelts are obtained, respectively. The time-dependent experimental results at 180 °C reveal that the sizes of MnV₂O₆ nanobelts increase gradually with the reaction proceeding. Interestingly, as the reaction is carried out with the aid of H₂O₂ solution, flower-like MnV₂O₆ nanosheets are formed.     

Hydrothermal fabrication of copper sulfide nanocones and nanobelts

Novel copper sulfide nanocones and nanobelts have been hydrothermally fabricated at 140 °C for 24 h with acrylamide and sodium dodecyl benzene sulfonate (SDBS) as surfactants, respectively. X-ray diffraction (XRD) pattern indicates that the as-prepared samples are the pure hexagonal phase CuS. XPS spectra show that the ratio of Cu/S is about 1:1.084. The morphology was characterized by scanning electron microscopy (SEM) and field emission scanning electron microscopy (FE-SEM) techniques. Transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM) images reveal that nanocones and nanobelts grow along the [110] axis. The surfactant is found to be critical to the morphologies of the products. The possible formation mechanism is also discussed.