ZnO及其掺杂纳米粒子的反相微乳液法合成及表征

 分别以OP/正庚烷/正己醇/水溶液和吐温60/溴代十六烷基吡啶/二甲苯/正戊醇/水溶液反相微乳液体系,合成了ZnO及ZnO-Cr₂O₃,ZnO-Cr₂O₃-NiO,ZnO-Cr₂O₃-NiO-MnO掺杂纳米粒子.研究了前驱物、反应物浓度和后处理对粒子制备和粒径的影响.结果表明:所给微乳液体系适合ZnO及其掺杂纳米粒子的制备;通过选择反应途径及控制反应物浓度可实现对粒径的控制;ZnO纳米粒子的粒径为10～200nm,二元、三元、四元掺杂型纳米粒子的粒径均约为20nm.     

Production and characterization of ZnO nanoparticles and porous particles by ultrasonic spray pyrolysis using a zinc nitrate precursor

ZnO nanoparticles and porous particles were produced by an ultrasonic spray pyrolysis method using a zinc nitrate precursor at various temperatures under air atmosphere. The effects of reaction temperature on the size and morphology of ZnO particles were investigated. The samples were characterized by energy dispersive spectroscopy, X-ray diffraction, transmission electron microscopy, and scanning electron microscopy. ZnO particles were obtained in a hexagonal crystal structure and the crystallite shapes changed from spherical to hexagonal by elevating the reaction temperature. The crystallite size grew by increasing the temperature, in spite of reducing the residence time in the heated zone. ZnO nanoparticles were obtained at the lowest reaction temperature and ZnO porous particles, formed by aggregation of ZnO nanoparticles due to effective sintering, were prepared at higher temperatures. The results showed that the properties of ZnO particles can be controlled by changing the reaction temperature in the ultrasonic spray pyrolysis method.     

Thermodynamics and phase transformations in the recovery of zinc from willemite

Willemite is a common component of zinc and lead metallurgical slags that, in the absence of effective utilization methods, cause serious environmental problems. To solve this problem and increase zinc recovery, we proposed a novel extraction method of zinc from willemite by calcified roasting followed by leaching in NH₄Cl-NH₃·H₂O solution. The thermodynamics and phase conversion of Zn₂SiO₄ to zinc oxide (ZnO) during calcified roasting with CaO were investigated. The mechanism of mineralogical phase conversion and the effects of the CaO-to-Zn₂SiO₄ mole ratio (n(CaO)/n(Zn₂SiO₄)), roasting temperature, and the roasting time on zinc-bearing phase conversion were experimentally investigated. The results show that Zn₂SiO₄ was first converted to Ca₂ZnSi₂O₇ and then to ZnO. The critical step in extracting zinc from willemite is the conversion of Zn₂SiO₄ to ZnO. The zinc percent leached in the ammonia leaching system rapidly increased because of the gradual complete phase conversion from willemite to ZnO via the calcified roasting process.     

ZnO纳米片的水热合成及其光催化性能

目的以Zn(CH_3COO)_2·2H_2O和NaOH为原料,制备ZnO纳米粒子,并研究ZnO纳米材料的形貌对其光催化性能的影响。方法采用一步水热法合成ZnO片状纳米粒子,通过X-射线粉末衍射(XRD),场发射扫描电镜(FE-SEM)和拉曼光谱(Raman)等分析手段对合成产物的结构和形貌进行表征,探讨反应物摩尔比、水热温度和水热时间等合成条件对形成的ZnO纳米粒子形貌的影响,以及形貌演变机理。通过光催化分解水实验对所制备的ZnO纳米粒子的光催化性能进行测试。结果 Zn~(2+)/OH~-摩尔比为1∶4时,在100℃反应6h,可制得片状的纳米ZnO,其产氢量为313μmol·h~(-1)·g~(-1)。结论在本文制备的ZnO纳米材料中,ZnO纳米片的光催化性能优于短棒状和纤维状的ZnO粒子。     

微波加热制备高分散性纳米氧化锌粉体

为了研究纳米氧化锌粉体干燥和热分解时的团聚问题,以硝酸锌和碳酸钠为原料,采用直接沉淀法制备前驱体,无水乙醇洗涤后,通过微波加热前驱体制备出了纳米氧化锌粉体。用TEM、FT—IR、TG—DTA、XRD等测试手段对样品进行了表征。结果表明：所得纳米氧化锌属于六方纤维矿的单晶结构,平均粒径为30nm,分布均匀,分散性好;无水乙醇洗涤和微波加热可有效避免纳米氧化锌粉体干燥和热分解时的团聚问题。并就微波加热和乙醇洗涤对产品分散性的影响机理做了初步探讨。     

Shape control technology during electrochemical synthesis of gold nanoparticles

Gold nanoparticles with different shapes and sizes were prepared by adding gold precursor (HAuCl₄) to an electrolyzed aqueous solution of poly(N-vinylpyrrolidone) (PVP) and KNO₃, which indicates the good reducing capacity of the PVP-containing solution after being treated by electrolysis. Using a catholyte and an anolyte as the reducing agents for HAuCl₄, respectively, most gold nanoparticles were spherical particles in the former case but plate-like particles in the latter case. The change in the pH value of electrolytes caused by the electrolysis of water would be the origin of the differences in shape and morphology of gold nanoparticles. A hypothesis of the H+ or OH? catalyzed PVP degradation mechanism was proposed to interpret why the pH value played a key role in determining the shape or morphology of gold nanoparticles. These experiments open up a new method for effectively controlling the shape and morphology of metal nanoparticles by using electrochemical methods.     

单分散ZnO微球的合成及表征

以Zn(NO3)2.6H2O为前驱体,采用水热法在三乙醇胺和水的混合溶剂中合成了单分散的ZnO微球。采用X射线衍射仪(XRD)、扫描电子显微镜(SEM)对ZnO微球进行表征。结果表明制备的样品具有六角纤锌矿结构,单分散的ZnO微球是由几十纳米的小颗粒聚集形成的。样品的形貌与三乙醇胺含量和前驱体浓度密切相关。随着三乙醇胺含量的增加,ZnO由不规则形状的颗粒转变为球形颗粒。此外,随着前驱体浓度增大,ZnO的形貌由球状变为六棱柱状。因此,要合成单分散的ZnO微球必须要严格控制前驱体浓度和三乙醇胺的含量。     

预制层结构对CZTS薄膜微观组织和光学性能的影响

研究了叠层顺序对磁控溅射沉积铜锌锡硫（CZTS）吸收层的微观结构、表面形貌和光学性能的影响.试验结果表明：当预制层结构为Cu/ZnS/SnS₂时,制备的CZTS薄膜在（112）晶面具有择优生长取向,并具有较好的结晶一致性,在288,335和368 cm^-1处呈现出特征拉曼（Raman）峰,薄膜表面晶粒较大、形状规则、薄膜空隙较少、比较致密,可见光范围内的吸收系数较高,光学带隙1.5 eV,适合作为CZTS薄膜太阳能电池的吸收层;当预制层结构为SnS₂/Cu/ZnS和ZnS/SnS₂/Cu时,由于在预制层硫化过程中造成一定的Zn和Sn流失,使CZTS薄膜中含有CuS杂相,导致薄膜表面质量下降,禁带宽度增加,不适合做CZTS薄膜太阳能电池的吸收层.     

Formation of highly crystalline maghemite nanoparticles from ferrihydrite in the liquid phase

Fe₅O₇(OH)·4H₂O ferrihydrite is a low-crystallinity antiferromagnetic material. γ-Fe₂O₃ (maghemite) magnetic nanoparticles were prepared from a ferrihydrite precursor, by chemically induced transformation in FeCl₂/NaOH solution. The magnetization, morphology, crystal structure and chemical composition of the products were determined by vibrating sample magnetometry, transmission electron microscopy, X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy (XPS). Ferrihydrite underwent aggregation growth and transformed into α-FeO(OH) (goethite) particles, which subsequently transformed into γ-Fe₂O₃ nanoparticles, that became coated with NaCl. The γ-Fe₂O₃ particles had a flake-like morphology, when prepared from 0.01 mol/L FeCl₂ and a FeCl₂:NaOH molar ratio of 0.4. The γ-Fe₂O₃ particles were more spherical, when prepared from a FeCl₂:NaOH molar ratio of 0.6. The Fe content of the flake-like particles was lower than that of the spherical particles. Their magnetizations were similar, and the coercivity of the flake-like particles was larger. The differences in morphology and magnetization were attributed to the surface effect, and the difference in coercivity to the shape effect.     

Sb2S3纳米粒子敏化ZnO微纳分级结构的光电化学性能

采用电化学沉积方法,选择聚乙二醇(PEG-400)和乙二胺(EDA)为添加剂,直接在ITO导电玻璃上制备了有序阵列的ZnO纳米棒,以及ZnO纳米棒上生长纳米棒微纳分级结构。采用化学浴沉积法均匀沉积Sb2S3纳米粒子,制备了Sb2S3/ZnO纳米棒壳核结构和Sb2S3/ZnO纳米棒上生长纳米棒分级壳核结构。利用扫描电子显微镜(SEM)、X射线衍射(XRD)、紫外-可见吸收光谱(UV-vis)、瞬态光电流等分析手段对其形貌、结构和光电化学性能进行了表征和测试。研究表明,Sb2S3/ZnO纳米棒上生长纳米棒分级壳核结构阵列膜的光电流明显高于Sb2S3/ZnO纳米棒壳核结构阵列。     

纳米ZnO的温和液相法制备及其光催化性能

以ZnCl₂作为锌源,采用液相法制备了由粒径约17 nm的氧化锌粒子组合而成的花状六方纤锌矿晶体结构的氧空位缺陷型ZnO纳米材料,对制备的ZnO纳米材料的结构、形貌和成分进行了表征,计算了其禁带宽度,并通过光催化降解亚甲基蓝研究了其光催化性能.结果表明:氧空位缺陷型ZnO纳米材料具有很好的结晶度和形貌,且禁带宽度为3.17 eV,低于普通ZnO的禁带宽度.当光催化降解亚甲基蓝溶液0.5、2.5 h时,降解率分别为20%和80%,降解速度是普通Ag纳米颗粒掺杂氧化锌的4倍,表明制备的氧空位缺陷型ZnO纳米材料具有优异的光催化性能.     

ZnSe纳米颗粒的制备及光学性能研究

以硝酸锌和硒粉为源物质,以乙二醇和氢氧化钠的水溶液为反应介质,采用水热法制备了ZnSe纳米颗粒,利用差热分析仪(TG-DTA)、X射线衍射仪(XRD),扫描电子显微镜(SEM)和光致发光谱(PL)对产物进行热稳定性、结构、形貌和光学性能表征.差热结果表明ZnSe在常温下具有一定稳定性,直到450℃以上时在空气中可转化为ZnO纳米材料.XRD和SEM研究结果表明,纳米颗粒具有闪锌矿结构并且随着反应时间的增加颗粒尺寸有所增大.PL测试显示近带边发射峰较强,这说明产物的结晶状况良好,并且具有较好的光致发光性能.     

Structural and electrical properties of ZnO films on freestanding thick diamond films

In this paper, ZnO films are deposited on freestanding thick diamond films （FTDF） by plasma-assisted metal organic chemical vapour deposition （MOCVD）. Diethyl zinc （DEZn）, O2 and N2O are applied as precursors and different substrate temperatures are used to achieve high quality ZnO films. The influence of substrate temperature on the properties of ZnO films is systematically investigated by X-ray diffraction （XRD）, Hall measurements and electron probe microanalysis （EPMA）. Experimental results demonstrate that ZnO films deposited at 600℃ and 73 Pa display a fine electrical quality and Zn/O atomic ratio plays an important role in the electrical property of ZnO films.     

Zn基ZnO纳米棒阵列的制备和发光特性

N2H4.H2O水热体系中,在Zn基底上制备出了ZnO纳米棒薄膜。采用X射线衍射(XRD)、场发射扫描电镜(FESEM)及发致发光谱(PL)等分析测试手段,研究了ZnO薄膜的形貌结构和发光特性。结果表明,预处理工艺不同,Zn基底表面状态不同,ZnO薄膜形貌也不同。在经预氧化形核的Zn基底上易于制备ZnO纳米棒薄膜。在单一取向的Zn基面上,易于制备ZnO纳米棒阵列。PL测试分析表明,ZnO纳米棒有强的近带边紫外光发射峰和弱的缺陷发射峰。阵列棒本征发射峰强度最高、缺陷峰最弱,反映了该ZnO纳米棒结晶质量高。     

锌掺杂对Li4Ti5O12负极材料电化学性能的影响

通过溶胶凝胶法制备Li4Ti5O12及锌掺杂Li4-2x/3ZnxTi5-x/3O12(x=0.05,0.10,0.15,0.20)活性材料,并优化了最佳掺杂量为x=0.10。通过X射线衍射(XRD)、扫描电镜(SEM)、恒流充放电测试对材料进行结构、形貌及电化学性能表征。结果表明:掺杂适量的锌离子不会改变钛酸锂的尖晶石结构和形貌,1C时,Li3.93Zn0.10Ti4.97O12放电比容量升高且容量保持率为99.74%;而纯相的容量保持率仅为94.30%。     

Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate (reference ZB) as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time (1–5 h), reactant ratio (H₃BO₃/ZnO by mass: 2–5), seed ratio (seed crystal/(H₃BO₃+ZnO) by mass: 0–2wt%), reaction temperature (50–120℃), cooling temperature (10–80℃), and stirring rate (400–700 r/min); the modifying agents involve propylene glycol (PG, 0–6wt%), kerosene (1wt%–6wt%), and oleic acid (OA, 1wt%–6wt%) with solvents (isopropyl alcohol (IPA), ethanol, and methanol). The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.     

A novel non-enzymatic hydrogen peroxide sensor based on Co:ZnO modified electrodes

There is currently intense interest in the use of nanoparticles for a wide range of biomedical and technological applications. In this paper, the hierarchical Co doped ZnO nanoflowers were synthesized by a facile wet chemical method and explored as biosensing material. The as-modified novel hydrogen peroxide sensor exhibited a wide linear range(0.25–20 mM), highly reproducible response(R.S.D. of 2.7%) and long-term stability. The doping Co~(2+)ions carried out the oxidations rapidly and efficiently for the catalysis of hydrogen peroxide(H_2O_2). A high activity toward H_2O_2 in the presence of ascorbic acid(AA) and NaNO_2, which are only common for natural enzymes, has also been demonstrated. The good analytical performance, low cost and straightforward preparation method makes this doped semiconductor promising for a wide range of potential applications in medicine, biotechnology and environmental chemistry.     

One-pot synthesis and optical properties of In-and Sn-doped ZnO nanoparticles

Colloidal indium-doped zinc oxide (IZO) and tin-doped zinc oxide (ZTO) nanoparticles were successfully prepared in organic solution,with metal acetylacetonate as the precursor and oleylamine as the solvent.The crystal and optical properties were characterized by X-ray diffraction,UV-visible spectrophotometry,and fluorescence spectroscopy,respectively;the surface and structure morphologies were observed by scanning electron microscopy and transmission electron microscopy.The XRD patterns of the IZO and ZTO nanoparticles all exhibited similar diffraction peaks consistent with the standard XRD pattern of ZnO,although the diffraction peaks of the IZO and ZTO nanoparticles were slightly shifted with increasing dopant concentration.With increasing dopant concentration,the fluorescent emission peaks of the IZO nanoparticles exhibited an obvious red shift because of the difference in atomic radii of indium and zinc,whereas those of the ZTO nanoparticles exhibited almost no shift because of the similarity in atomic radii of tin and zinc.Furthermore,the sizes of the IZO and ZTO nanoparticles distributed in the ranges 20-40 and 20-25 nm,respectively,which is attributed to the difference in ionic radii of indium and tin.     

纳米ZnO光催化降解有毒有机污染物

分别以硝酸锌,醋酸锌,氯化锌和硫酸锌为锌源采用水热法制备了纳米ZnO,通过X射线衍射仪（XRD）和透射电子显微镜（TEM）对ZnO进行了表征,结果表明：四类锌源制备的ZnO均为六方晶系的纤锌矿结构,尺寸在23.9～62.6 nm.在紫外光照射下以罗丹明B（Rhodamine B,RhB）和2,4-二氯苯酚（2,4-Dichlorophenol,2,4-DCP）的光催化降解为探针反应,研究了介质pH条件和催化剂用量等对光催化反应的影响,表明pH=6.2和催化剂用量为0.4 g.L-1条件下以硝酸锌为锌源制备的ZnO活性最好,60 min内RhB褪色完全,120 min内2,4-DCP降解率达到97%.通过总有机碳（TOC）的测定,发现6 h内RhB矿化率达到95.2%.采用辣根过氧化物酶（POD）法和苯甲酸荧光光度法分别测定了体系中H2O2和羟基自由基（.OH）的变化,表明其光催化反应机理涉及.OH历程.     

采用聚氨酯模板法制备花形纳米氧化锌

以乙酸锌(Zn(CH3COO)2)为锌源,尿素(CO(NH2)2)为碱源,非离子型聚氨酯(PU)为模板,采用水热法制备碱式碳酸锌(Zn5(CO3)2(OH)6)前驱体.在400 ℃进一步煅烧前驱体2 h,即获得氧化锌粉末.用粉末X射线衍射和扫描电镜研究产物的形貌和结构.结果表明:以PU为模板制备的氧化锌可以获得由纳米片状结构组成的花状形貌,PU的加入可以有效减小氧化锌的晶粒尺寸.进一步研究反应物的组成、反应温度及反应时间对产物结构的影响,发现当体系中碱源(OH-)和锌源(Zn2+)的摩尔比为4,水热反应时间为18 h,反应温度为150 ℃时,前驱体可以获得最完整的花状形貌,并且煅烧后氧化锌的花形形貌不变.