水热法制备花状和菜花状氧化锌

以Zn(NO3)2·6H2O和N2H4·H2O为原料,采用水热法在180℃下保温24 h,制备了花状和菜花状的氧化锌(ZnO)纳米棒束.用XRD、SEM、FE-SEM及HR-TEM对样品进行了表征.XRD结果表明所制样品为六方纤维锌矿结构的ZnO晶体;SEM及FE-SEM测试结果显示ZnO晶体的形貌呈花状和菜花状,且由直径约100 nm的纳米棒组成;HR-TEM结果表明单晶纳米棒沿[0001]方向生长最快.结合测试结果,分析、讨论了花状和菜花状ZnO纳米棒束的生长机理及N2H4·H2O在ZnO生长过程中的作用.     

纳米复合材料Ag/ZnO的制备及紫外光催化降解染料

采用溶胶-凝胶-程序升温溶剂热一步法制备了纳米复合材料Ag/ZnO,通过X射线衍射（XRD）以及扫描电子显微镜配合X-射线能量色散谱仪（SEM-EDS）等测试手段对其结构、形貌等进行了表征。结果表明,复合材料中Ag成功地掺杂在ZnO上,且合成产物Ag/ZnO具有六方晶系纤锌矿结构。为考察上述复合材料的光催化活性,在紫外光照射下,对酸性品红、罗丹明B、孔雀石绿、亚甲基蓝等染料进行了光催化实验研究,结果表明,该复合材料具有较好的可见光催化活性。     

Au修饰ZnO纳米带制备及光催化特性研究

通过水热法制备ZnO纳米带,通过溅射的方法在ZnO纳米带进行表面Au修饰.通过扫描电镜、X射线衍射、光致发光等测试手段对样品的形貌、结构和光学性质进行表征.研究ZnO纳米带Au修饰前后的光催化活性的变化.结果表明,Au修饰ZnO纳米带样品对甲基橙降解效果有明显的提高.     

水热法可控合成ZnO纳米棒及其光催化性能研究

以ZnSO4.7H2O和NaOH为主要原料,通过简单的一步水热合成路线,制备出平均直径为100～200 nm,长度为2.0～3.0μm,沿[0001]方向择优生长的ZnO纳米棒.利用XRD、SEM和紫外可见光吸收光谱研究了OH-浓度和水热反应时间对产物形貌及光催化活性的影响.研究结果表明,所获得的ZnO纳米棒对亚甲基蓝具有良好的光催化活性,通过调整OH-浓度和水热反应时间可以实现ZnO纳米棒的可控合成,OH-浓度和水热反应时间对产物的形貌和光催化活性影响显著.     

微波水热法制备花状氧化锌光催化剂的研究

以乙酸锌和氨水为原料,采用微波水热法成功制备出了花状ZnO光催化剂。探讨了溶液Zn~(2+)初始浓度、pH值和微波加热时间对ZnO物相、形貌及光催化性能的影响。XRD表明制备的样品均为纤锌矿结构,晶型完整且部分ZnO样品晶粒沿(002)晶面发生了取向性生长;SEM表明pH值对ZnO形貌有着重要影响,pH值过低(pH<10.0)时,无法形成花状ZnO,pH过高(pH>10.7)时,花状ZnO"花瓣"会变形甚至溶解;UV-Vis表明制备的ZnO样品的吸收带均发生了红移,拓宽了光催化剂的吸收波长范围;反应条件对ZnO光催化性能的影响主次关系为:pH值>Zn~(2+)初始浓度>微波加热时间,较优工艺及工艺参数为:初始反应Zn~(2+)浓度为0.15 mol/L,pH值为10.5,微波加热时间为2.5 h,较优样品在紫外光辐照4 h后对亚甲基蓝溶液的降解率为85.90%。     

N-Ag/ZnO纳米复合材料的合成及模拟日光下的光催化性能

以NH3为N源,通过气氛渗氮法对采用配合物沉淀法制备出的Ag/ZnO纳米材料进行N掺杂,制备出N-Ag/ZnO纳米复合材料。应用X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)、紫外-可见吸收光谱(UV-Vis)等测试手段对制备产物的物相结构、微观形貌及吸光性能进行了表征。以甲基橙(MO)为目标污染物,研究了制备产物在模拟日光照射下的光催化性能。结果表明:Ag粒子附着于棒状ZnO表面,N进入ZnO晶格;N掺杂能够显著提高Ag/ZnO纳米复合材料的光催化性能及其稳定性,以N-Ag/ZnO为光催化剂,在模拟日光下照射降解MO 100min,MO的降解率达到100%,较Ag/ZnO提高25%,且放置30d后光催化性能基本保持不变。     

一维纳米结构ZnO的制备

采用溶胶-凝胶法,以醋酸锌(Zn(CH3COO)2.2H2O),草酸((COOH)2.2H2O)和无水乙醇为原料,制备得到了粒子直径在30 nm左右、粒度分布均匀、分散性较好的球状纳米ZnO粒子.以上述反应为基础,在反应体系中加入一定量的有机添加剂三乙醇胺,得到了棒状结构的纳米ZnO.利用透射电子显微镜(Transmission Electron Microscopy,TEM)研究了有机添加剂三乙醇胺的加入对产物纳米ZnO形貌的影响.实验结果表明:有机添加剂三乙醇胺在棒状纳米ZnO的形成过程中起决定性作用,并且所形成的棒状纳米ZnO的形貌随添加剂用量的不同而不同,所以调节三乙醇胺的加入量可以有效地控制纳米ZnO的形貌.     

pH值对BiOIO_3结构及其光催化性能影响研究

采用水热合成法通过调控反应前驱液pH值制备出具有不同形貌结构的碘酸氧铋(BiOIO_3)光催化剂。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和紫外-可见吸收光谱(UV-vis)等测试方法对合成的样品进行物相、形貌及光学性能表征。以罗丹明B和2,4-二氯苯酚的降解效率来评价在不同合成条件下所制备BiOIO_3的光催化活性。结果表明,反应前驱液的pH值影响所合成BiOIO_3的形貌结构及光催化性能,只有反应液的pH值在酸性条件下,所得产物为纯的BiOIO_3。在pH值为2～3的酸性范围内所制备的BiOIO_3纳米片具有优异的光催化活性,光辐射15 min时,罗丹明B的降解效率可达95%,光生空穴是主要的氧化活性基团。     

不同形貌氧化锌的红外发射率研究

在水热条件下,以硝酸锌、氢氧化钠、六次甲基四胺等为原料合成球形、棒状、束状和花状等不同微观形貌的ZnO粒子。采用透射电镜（TEM）、扫描电镜（SEM）和X射线衍射（XRD）等对其形貌和物相进行分析,利用IR-1红外发射率测量仪测量了不同形貌ZnO粒子在8~14μm波段的红外发射率,探讨ZnO的形貌对其红外发射率性能的影响。结果表明：各产物均为六方纤锌矿结构的ZnO,微米ZnO的红外发射率值比纳米的小,棒状、束状ZnO的发射率值比球形的要低,花状结构的ZnO的发射率值最低,为0.673。     

纳米ZnO催化生物乙醇转化的形貌效应

利用水热法合成了棒状、片状、球状结构的氧化锌(ZnO)纳米晶粒,评价了不同形貌的纳米ZnO对生物乙醇转化的催化活性,并采用扫描电子显微镜(SEM)、X线衍射(XRD)及程序升温脱附(NH_3-TPD,CO_2-TPD)等研究手段对ZnO的形貌及表面酸碱性等物相结构进行了表征.结果表明:不同形貌的纳米ZnO具有不同的表面酸碱性,从而在生物乙醇催化转化的反应路径及产物选择性调控方面表现出一定的形貌效应.     

六方相NaYF_4微米棱柱晶体的水热生长

通过温和的水热方法合成了六方相NaYF4微米棱柱.场发射扫描电镜（FE-SEM）和透射电子显微镜（TEM）分析表明：该晶体结晶性较好,尺寸均一,直径约为1μm,长度约为5μm,晶体笔直且边缘清晰.研究发现六方相NaYF4微米棱柱是随着反应时间的延长由微米花状球上脱落而成的.提出了其可能的生长机制.     

Controlling growth of ZnO nanostructures via a solution route

A solution method was developed for fabricating ZnO nanostructures using (NH₄)₂CO₃ as starting material. SEM analysis shows that ZnO nanostructures exhibit nanorod, branch and flower-like morphologies. The crystal phase of as-synthesized products was characterized by X-ray diffraction (XRD). The growth process, formation mechanism and optical property were also discussed by means of transmission electronic microscopy (TEM), high resolution transmission microscopy (HRTEM) and photoluminescence (PL). The growth direction of ZnO nanostructures was investigated based on the results of HRTEM. The PL spectrum shows two strong peaks (centered at around ∼387 and ∼470 nm) and a broad peak (centered at around ∼580 nm). Funded by the Ministry of Education of China (PCSIRT0644)     

Preparation and characterization of three-dimensional chrysanthemun flower-like calcium carbonate

Calcium carbonate with three-dimensional chrysanthemun flower-like structure was successfully prepared from calcium chloride and sodium carbonate ethanol/water mixed solution by a simple precipitation method,using trisodium citrate as crystal modifier.The experimental results show that the three-dimensional structure of chrysanthemun flower-like calcium carbonate is built up with several symmetrical micrometer multi-layer petals arranged around the multi-layer pancake-liked center,and the micrometer center and petals are assemblied by a large number of nanometer spherical particles with size 10-20 nm.It is found that the amount of trisodium citrate,the ethanol volume content has an important influence on the formation of this morphology.A possible mechanism is proposed to explain the formation of three-dimensional chrysanthemun flower-like calcium carbonate according the results.Scanning electron microscopy(SEM),X-ray powder diffraction(XRD),flourier transform infrared spectroscopy(FT-IR),thermogravimety analysis(TG),transmission electron microscopy(TEM) equipped with energy-dispersive X-ray(EDX),and selected area electron diffraction(SAED) were used to characterize the crystals.     

水热法合成分层的羟基氧铝纳米结构

在表面活性剂PVP和CTAB的辅助下采用简单的水热法,成功地合成了不同形貌的AlOOH.同时,通过XRD,TEM,HRTEM,SAED等一系列手段对其进行探讨和研究,结果表明:反应时间和表面活性剂的浓度对样品的形貌起到了至关重要的作用.此外,实验研究发现表面活性剂PVP和CTAB在反应中起到不可替代的作用.目前还没有任何文章报道有关在水热条件下采用简单的方法合成不同形貌的AlOOH.     

锡酸镧(La2Sn2O7)花状纳米结构的水热合成及表征

采用简单、中性的水热法成功地制备了锡酸镧（La2Sn2O7）花状纳米结构,并采用X射线衍射（XRD）、透射电镜（TEM）和漫反射光谱（DRS）等手段对产物的晶体结构、形貌和光学性能进行了分析。结果表明：所得产物为单相烧绿石结构的锡酸镧,并呈现由纳米杆组成的花状纳米结构,纳米杆的直径和长度分别约为20 nm和150nm。由分析DRS光谱可得,锡酸镧花状纳米结构的禁带宽度约为3.85 eV,并对该花状纳米结构的形成机理进行了初步探讨。     

Characterization of structural and electrical properties of ZnO tetrapods

ZnO tetrapods were synthesized by a typical thermal vapor-solid deposition method in a horizontal tube furnace.Structural characterization was carried out by transmission electron microscopy (TEM) and select-area electron diffraction (SAED),which shows the presence of zinc blende nucleus in the center of tetrapods while the four branches taking hexagonal wurtzite structure.The electrical transport property of ZnO tetrapods was investigated through an in-situ nanoprobe system.The three branches of a tetrapod...     

Large scale synthesis of ZnO nanoparticles via homogeneous precipitation

In order to synthesize ZnO nanoparticles economically, industrial-grade zinc sulfate and urea were utilized to synthesize ZnO precursors in a stirred-tank reactor or a Teflon-lined autoclave at 100–180 °C under complete sealing condition. The ZnO precursors were calcined at 450 °C for 3 h to synthesize ZnO nanoparticles. The composition of the precursors and the formation mechanism of ZnO were studied by thermogravimetric analysis and Fourier transform infrared spectroscopy. The results of X-ray diffraction, transmission electron microscopy and scanning electron microscopy of the ZnO powders demonstrate that high-purity zincite ZnO nanoparticles are synthesized. Orthogonal experiments were performed to find out the optimal conditions for the maximum yield and the minimum size. The effect of temperature on the size of ZnO nanoparticles was investigated. The results show that a higher temperature is propitious to obtain smaller nanoparticles.     

A facile synthesis of Ag Modified ZnO nanocrystals with enhanced photocatalytic activity

Ag modified ZnO (Ag/ZnO) nanocrystals were prepared by a facile and low temperature wet chemical method. The phase structures, morphologies, and optical properties of the as-prepared samples were characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), the Brumauer-Emmett-Teller (BET) surface area, UV-vis diffuse reflectance spectroscopy and photoluminescence (PL) spectra, respectively. The photocatalytic performance of Ag/ZnO with diffent Ag contents was measured with the degradation of methyl orange (MO) at room temperature under UV light irradiation. The experimental results indicated that the well-crystalline ZnO nanopaticles with a size of ca. 4.5 nm exhibited a high photocatalytic activity for the degradation of MO with the apparent rate constant (k) of 1.57 ×10-2 min-1, and the photocatalytic activities of ZnO were further enhanced by modification with silver. When the Ag loading was 3mol%, Ag/ZnO showed the highest photocatalytic acitivity with a k value of 5.452×10-2 min-1, which is 3.5 and 2.5 time more than that of ZnO and commercial P25, respectively.     

Decorating multiwalled carbon nanotubes with zinc oxide nanoparticles by thermally decomposing Zn-oleate in an organic medium

Carbon nanotubes decorated with zinc oxide nanoparticles were produced by thermally decomposing a Zn-oleate complex in an octadecene medium. The structure of the ZnO decorating nanotube surfaces was characterized by transmission electron microscopy, scanning electron microscopy and X-ray diffraction. The surfaces were shown to be densely and homogeneously covered by ZnO nanoparticles with a size below 10 nm. The nanoparticles had the wurtzite hexagonal crystal structure and showed good adhesion to the nanotubes. The carbon nanotubes decorated by metal oxide nanoparticles were synthesized at relatively low temperature and non-oxidation environment. Moreover, the large-scale production with low cost can be realized.