“三明治”PbS纳米晶/rGO复合材料的制备及其对NH_3的室温气敏性能研究

采用一步溶液法制备"三明治"PbS纳米晶/rGO复合材料,通过X射线衍射仪和场发射扫描电子显微镜对样品的晶体结构和表面形貌进行表征,并制作旁热式气敏元器件,测试其气敏特性。研究结果表明在PbS纳米晶/rGO复合材料中,PbS纳米晶均匀负载在rGO片层上,且复合材料存在类似"三明治"的三维结构。该复合材料在室温下对NH_3具有良好检测能力,对1000 ppm NH_3的灵敏度达到3.45,与纯PbS纳米晶及rGO相比,气敏性能得到显著提升,其最低检测极限为1 ppm,且具有良好的氨气选择性。对"三明治"PbS纳米晶/rGO复合材料气敏机理进行分析认为,rGO加入起到载流子传输层的作用,三维结构增加气体扩散速度及吸附面积。三明治状PbS纳米晶/rGO复合材料因其特殊结构及优异的气敏性能,有望在气敏领域得到广泛应用。     

球状PbS纳米颗粒的室温合成与性能表征

以醋酸铅为铅源,硫代乙酰胺为硫源,在表面活性剂十二烷基硫酸钠(SDS)和十六烷基三甲基溴化铵(CTAB)共同作用下,在常温下合成了PbS纳米晶,利用XRD、紫外分光度计、SEM、TEM对合成产物的结构和形貌以及光学特性进行了表征分析,结果表明,合成的PbS为尺寸均匀的球形纳米晶,对合成的PbS纳米晶的形成机理进行了初探.当反应温度较低时,形成的PbS小颗粒在表面活性剂SDS的烷基链模板和CTAB微胶束软模板共同作用下生成球状PbS纳米晶.     

PbS/CdS纳米晶共敏化ZnO纳米线太阳能电池的性能研究

以Zn (Ac)2·2H2O为原料在强碱性条件下合成一维结构的ZnO纳米线,SEM结果表明合成的纳米线尺寸、形貌、长径比均一;并以油胺为单一溶剂采用热注射法制备了形貌、尺寸均匀的PbS纳米晶;构建PbS纳米晶敏化ZnO纳米线基太阳能电池,同时为了改善电池的光电转换效率并构建了PbS/CdS纳米晶共敏化电池,并测试了电池的光电流密度-光电压(J-v)曲线以及Nyquist曲线图,结果表明PbS/CdS纳米晶共敏化电池性能明显优于单纯的PbS纳米晶敏化ZnO纳米线太阳能电池.     

煅烧制度对Lu2Ti2O7粉体生长形貌的影响

采用熔盐法制备Lu2Ti2O7粉体,研究了不同煅烧工艺对粉体形貌的影响,确定了适用于Lu2Ti2O7粉体合成的工艺条件,并在利用XRD、SEM等方法分析表征样品的基础上,提出了初步的粉体形貌生长转变机制。实验结果表明:形核速率和生长速率对粉体的颗粒尺寸和形状影响很大,过快的形核速率和生长速率有利于多面棱柱状晶粒的生长,反之则有利于八面体形状的晶粒生长。     

SnS片状纳米晶的制备及其表征

用水热法制备了SnS片状纳米晶.通过X射线衍射(XRD),扫描电子显微镜(SEM),透射电子显微镜(TEM),X射线能谱(EDS)等方法对所制备的样品SnS粉晶的结构形貌及组分进行了表征.研究了影响合成SnS片状纳米晶的几个因素,讨论了片状纳米晶生长过程与(040)晶面择优取向的关系,并分析了SnS片状纳米晶的合成机理.     

CuCl枝晶与单质Cu枝晶的生长与枝晶形貌结晶学分析

以锌粉和氯化亚铜为原料,采用水热法,制备了单质Cu枝晶与CuCl枝晶.利用X-射线衍射仪(XRD)、能谱仪(EDS)和扫描电子显微镜(SEM),对枝晶产物和生长机理进行了表征.结果表明:单质Cu枝晶多为黄色具有金属光泽的三维树枝状结构,也可见二维枝状结构;CuCl枝晶为白色二维叶片状结构.尽管CuCl叶片在整体的外形上略有不同,但结晶学特征是相同的,都可以观察到明显的主干,在主干的两侧均有侧枝,且侧枝与主干之间呈60°夹角关系,同侧的侧枝之间彼此平行排列.通过对叶片状枝晶的结晶学规律的分析发现:CuCl枝晶的主干是由四面体单体沿[121]方向以平行连生方式形成,侧枝是四面体单体分别沿[211]和[112]平行连生而成.     

ZnO/PbS量子点异质结太阳能电池结构调控研究

利用氧化锌溶胶-凝胶(Sol-Gel)、锌盐乙醇溶液(ES)和氧化锌纳米粒子溶液(NP)三种不同的籽晶层前驱液,在ITO衬底上通过化学浴沉积方法(CBD)制备出了一维氧化锌纳米棒阵列薄膜,并在所制备的氧化锌纳米棒阵列薄膜上构筑了具有“三维”异质结结构的PbS量子点太阳能电池.通过扫描电镜(SEM)、X射线衍射(XRD)和透射光谱分析等研究了籽晶层对氧化锌纳米棒阵列薄膜形貌、结构和光学性质的影响;结合电池性能测试结果,比较分析了“三维”异质结结构和“平面”异质结结构对电池性能的影响.结果表明:在ES籽晶层上生长的氧化锌纳米棒阵列薄膜的取向性最好,Sol-Gel次之,NP最差;在ES和Sol-Gel籽晶层上生长2h的样品透射率在80;左右;与“平面”异质结结构PbS量子点电池相比,基于氧化锌纳米棒阵列薄膜制备的“三维”异质结结构电池的短路电流可提高40;,表明“三维”异质结结构有利于载流子的分离和输运.     

四足棒球棒状ZnO纳/微米材料的制备及其生长机理的研究

采用简单的碳热蒸发法在硅衬底上制备了四足棒球棒状ZnO纳/微米材料,结合光致发光谱(PL)、阴极射线发光谱(CL)、XRD谱、SEM以及TEM等分析了该材料的结构和发光特性.结果表明,制备的单晶ZnO纳/微米材料具有纤锌矿结构,并且沿着c轴方向择优生长;每个纳/微米结构有四个足,每个足的直径约为0.2～1.5 μm,长度约为3 ～10 μm;室温光致发光谱中包含一个384 nm附近的较弱的近紫外发光峰和一个519 nm附近的较强的绿色发光峰;在单个四足状ZnO纳/微米结构不同位置获得的阴极射线发光谱也被用于对比分析.最后讨论了Ni缓冲层的作用及ZnO四足棒球棒状的生长机理.     

熔盐法合成片状SrBi4Ti4O15粉体

采用NaC l-KC l熔盐法合成了生长各向异性的片状SrB i4Ti4O15粉体,用XRD分析了粉体相的结构,用SEM观察了粉体的微观形貌,讨论了不同预烧温度对合成物结构和微观形貌的影响。与固相法相比,熔盐法合成的粉体具有(00l)择优生长的优点。在850~1050℃之间,合成粉体的片状结构趋于明显,粉体生长各向异性随温度的升高呈现出先增加后减小的趋势,各向异性明显的SrB i4Ti4O15粉体的最佳合成温度为900~1000℃。     

三聚甲醛存在下EMT分子筛的合成及表征

以硅酸钠为硅源、铝酸钠为铝源,以三聚甲醛(TOX)为有机添加剂,室温下悬浮聚集陈化合成了EMT分子筛.考察了凝胶组成、晶化温度、晶化时间等因素对EMT分子筛合成的影响.采用XRD、FT-IR、SEM、BET、ICP等手段对EMT分子筛进行了表征.结果表明,合成EMT分子筛适宜的条件为:凝胶摩尔组成nNa2O∶nAl2O3∶nSiO2∶nH2O∶nTOX=18.5∶1∶5∶240∶0.5,晶化温度30 ℃,晶化时间72 h,此条件下合成的EMT分子筛,XRD特征峰较强,与典型的EMT分子筛的特征衍射峰相吻合,相对结晶度为80.1;,经ICP分析计算Si/Al=2.01,BET比表面积为80.57 m2/g,孔容和孔径分别为0.03 cm3 /g和2.07 nm,SEM照片显示EMT为球形晶体颗粒团聚状生长,大小均匀,排列紧凑.     

宽吸收带MEH-PPV/PbS量子点复合材料的制备

制备出粒径在3~8nm之间的宽吸收带聚合物MEH-PPV/PbS量子点复合材料。该材料在400~1100nm波长区域内表现出强吸收,能覆盖太阳光谱的大部分。准原位吸收光谱分析表明,MEH-PPV的加入不是获得宽吸收带纳米颗粒的主要因素。     

Synthesis via an organic molten salt solvent route and characterization of PbS nanocrystals

In this paper, four petals flowers‐like and quasi sphere‐like PbS nanostructures were successfully synthesized by an environment friendly organic molten salt solvent (OMSS) route at 200 °C, with different sulfur sources, e.g. thiourea and sodium thiosulfate, respectively. The as‐synthesized products were characterized by X‐ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), UV–vis absorption spectrum and photoluminescence (PL) spectrum, respectively. It was shown that four petals flowers‐like and quasi sphere‐like PbS nanocrystals were formed. It was also demonstrated that the morphologies of PbS nanocrystals were significantly influenced by different sulfur sources. The ultraviolet‐visible absorption peaks of PbS nanocrystals exhibited a large blue‐shift and the luminescence spectra had strong and broad emission bands centered at 488 nm and 492 nm. The possible formation mechanisms of the PbS nanostructures were discussed. The organic molten salt solvent (OMSS) method is preferable for synthesizing high‐quality PbS nanocrystals. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

PbS量子点/MoO3纳米带复合材料的低温气敏性能研究

采用液相法制备PbS量子点修饰MoO3纳米带复合材料.利用XRD、FESEM、TEM、EDS等表征手段分析样品组成、结构与形貌,分别将MoO3纳米带、PbS量子点、PbS量子点/MoO3纳米带组装成陶瓷管气敏元件并测试其对NH3的气敏性能.结果表明,在低温(20~100 ℃)下PbS量子点/MoO3纳米带复合材料对NH3具有良好检测能力,最低测试限为10 ppm.由于PbS量子点均匀分布在MoO3纳米带表面可形成异质结界面,这可有助于电子、空穴的分离,从而显著改善电子传输性能和气敏特性.     

Shape controllable growth of PbS polyhedral crystals

In this study, a series of PbS polyhedra were synthesized through hydrothermal decomposition of the as‐formed lead diethyldithiocarbamate (Pb‐DDTC) single‐source precursor in its precursor solution. Through extensive experiments, it was concluded that the amount of poly‐(vinylpyrrolidone) (PVP), DDTC and the reaction time had major effects on the shapes of the as‐synthesized PbS crystals. Sub‐micro sized cuboctahedrons and cubes were selectively obtained by manipulating the concentration of PVP and the reaction time. Possible growth mechanism for the shape controlled synthesis of PbS crystals was briefly discussed.     

pH值对电沉积PbS薄膜结构和性能的影响

采用阴极恒电压法在ITO导电玻璃表面沉积了PbS薄膜,并用X射线衍射仪(XRD)、原子力显微镜(AFM)以及傅立叶变换红外光谱仪(FT-IR)对薄膜的结构和光学性能进行了表征,研究了沉积液pH值对薄膜的相组成、显微形貌以及光学性质的影响.结果表明:在U=3 V,pH=2.4,沉积时间为20 min,加入EDTA作络合剂的情况下,可制备出沿(111)和(200)晶面取向生长的立方相PbS薄膜.薄膜均匀而致密,随pH值增加,薄膜的压应力及禁带宽度呈现先减小后增大的变化趋势.所制备的微晶PbS薄膜的禁带宽度约为0.38～0.39 eV.     

沉积温度对电沉积PbS薄膜结构和性能的影响

采用电沉积法在ITO导电玻璃表面沉积了PbS薄膜,并用X射线衍射仪(XRD)、原子力显微镜(AFM)以及傅立叶变换红外光谱仪(FT-IR)对薄膜的结构和光学性能进行了表征,研究了沉积温度对薄膜的相组成、显微形貌以及光学性质的影响.结果表明:在U=3 V,pH=2.5,T=60 ℃,沉积时间为20 min,加入EDTA作络合剂的情况下,可制备出沿(111)和(200)晶面取向生长的立方相PbS薄膜.薄膜显微结构均匀而致密,随着反应温度从20 ℃增加到60 ℃,薄膜内的压应力逐渐减小,禁带宽度也随着变小.所制备的微晶PbS薄膜的禁带宽度约为0.39 eV.     

Electroless deposition of Cu dendrites decorated with ZnO rods

In this paper, copper dendrites decorated with ZnO rods have been electrolessly deposited on brass substrate by a simple galvanic replacement method. SEM images show that these copper dendrites possess a pronounced trunk and highly ordered branches distributed on both sides of the trunk. Meanwhile, both the trunk and branches are decorated with ZnO rods. The diffusion‐limited aggregation (DLA) model has been used to explain the fractal growth of Cu dendritic structures. This method provides a facile route to the synthesis of copper dendrites with ZnO, which can be extended to the preparation of other forms three‐dimensional (3‐D) metal structures or metal/ZnO composites by modifying electrolyte parameters such as composition, concentration, pH and temperature. (© 2011 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation of PbS nano‐microcrystals with different morphologies and their optical properties

PbS nano‐microcrystals were prepared from Pb(OAc)₂·3H₂O and sulfur in a solution without any surfactant using the solvothermal process. Different morphologies, mainly including polyhedron microcrystals and sphere‐like assemblies, were characterized using a scanning electron microscope (SEM) and a transmission electron microscope (TEM). PbS nano‐microcrystals with cubic crystal structure were detected using X‐ray diffraction (XRD), electron diffraction (ED) and high resolution transmission electron micrograph (HRTEM) techniques. The optical properties were investigated by ultraviolet‐visible (UV‐vis) spectroscopy, and photoluminescence spectroscopy (PL). The UV‐vis absorption peaks of PbS exhibited a large blue‐shift and the PL spectra had a strong and broad emission bands centered at 408 nm. The crystal growth mechanism of PbS was also discussed.     

PbS crystals with clover‐like structure: Preparation,characterization, optical properties and influencing factors

A new and simple route to synthesize Lead sulfide (PbS) crystals with the clover‐like structure was described in the current paper. PbS was prepared in a simple aqueous solution employing (CH₃COO)₂Pb and thiourea as the initial materials under 130 W microwave irradiation. No any surfactant or template including organic polyamines with N‐chelation property was needed. The phase and composition of the product were identified by X‐ray powder diffraction (XRD) and X‐ray photoelectron spectra (XPS). TEM observation showed that the product with the six‐petal flower‐shaped structures was obtained, but SEM observation confirmed the clover‐like structure of the product; and the six‐petal flowers were formed via the overlap of two clovers revolved 60° around the center of the flower. Some factors affected the shape of the final product were studied and the optical properties of PbS crystals with the clover‐like structure were measured. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)