超声模板法制备纳米二氧化铈的研究

采用超声模板法结合共沸蒸馏和水热法处理前驱体成功制备出了纳米CeO2颗粒,通过TEM、XRD、FT-IR、UV-Vis等分析方法对产物形貌、结构和性能进行了表征;研究了模板剂的性质、模板剂的用量、共沸蒸馏和水热处理对纳米CeO2颗粒形态、尺寸的影响。实验结果表明,与OP-10和SDBS比较,CTAB最适合应用于制备纳米CeO2颗粒。当模板剂用量为n(CTAB)∶n(Ce(NO3)3.6H2O)=1∶2,制备出粒径约为6.1nm的球形纳米CeO2;共沸蒸馏能有效去除前驱体中的模板剂和吸附水,丁氧基的取代吸附及其空间位阻作用有利于制得分散性好、粒度分布均匀、粒径约为1.5～2.2nm的纳米CeO2颗粒;水热处理改善了纳米CeO2颗粒的晶化度,避免了高温焙烧过程时硬团聚体的生成,颗粒尺寸为2.5～3.8nm;纳米CeO2颗粒具有良好的可见光透过和优异的紫外光吸收性能。     

无团聚纳米氧化锆的制备及应用

采用高分子表面修饰－共沸蒸馏工艺成功地制备了纳米氧化锆微粒;合成过程中高 分子的空间位阻作用阻碍了前驱体颗粒的长大,通过与正丁醇的共沸蒸馏有效地脱除了前驱体 内的水分,在颗粒表面形成了正丁醇分子的包裹结构,在随后的干燥过程中避免了颗粒间形成 强化学键,获得了平均粒径在２０ｎｍ的无团聚的纳米微粒．纳米氧化锆微粒加入到润滑脂中能 明显改善后者的耐磨性能．     

制备低团聚掺锑氧化锡超细粉体的新方法

以SnCl4·5H2O和SbCl3为原料,用醇盐水解法制备了纳米掺锑氧化锡(ATO)导电粉体。用正丁醇—二甲苯的混合溶剂共沸蒸馏、有机脱水剂以及其它方法对前驱体胶态沉淀进行脱水处理,以消除粉体团聚。运用XRD、TEM、BET等手段对粉体进行表征,比较了各种脱水处理方法对ATO纳米导电粉体的粒度、团聚度、晶粒生长以及电阻率的影响。结果表明,混合溶剂共沸蒸馏处理以及有机脱水剂是比较有效的脱水方法,可以用来制备比表面积大(85.32m2·g—)、团聚小、电阻率低1的纳米ATO导电粉体。     

共沸蒸馏法制备单分散氧化镍微粉

先采用均匀沉淀法制得单分散的氧化镍前驱体粉末 ,然后用正丁醇进行共沸蒸馏脱水处理。经干燥、煅烧后成功地制成了单分散性相当好的氧化镍微粉。实验证明 ,共沸蒸馏能有效地脱除湿粉末中的水分 ,丁氧基取代了颗粒表面的羟基 ,从而防止了颗粒间Ni—O—Ni的形成 ,消除了硬团聚形成的可能性。     

醇盐水解法制备二氧化钛纳米粉体

利用控制醇盐水解的方法，分析采用正丁醇共沸蒸馏和乙醇洗涤这两种工艺，详细研究了超细二氧化钛粉体的制备过程，采和ＸＲＤ、ＴＥＤ、ＢＥＴ、ＴＧ和ＤＴＡ等方面对用直接沉淀、正丁醇共沸和乙醇洗涤三种方法获得的粉体进行了表征。发现用直接沉淀和乙醇洗涤法均能获得团聚少、颗粒在１５ｎｍ左右的粉体，且乙醇洗涤能进一步减少粉体的团聚，但共沸蒸馏反而增加了粉体的团聚度。     

纳米Ni(OH)2的控制结晶法制备

纳米Ni(OH)2可以有效地提升镍氢电池的性能.本文以NiSO4和NaOH为原料,聚乙二醇为分散剂,采用控制结晶法制备了纳米Ni(OH)2的胶体溶液,控制结晶的pH值和温度分别为11.0和45℃.然后用正丁醇进行共沸蒸馏处理.制备了分散性良好的纳米Ni(OH)2粉体,粉体颗粒粒径20nm左右,团聚体系数为1.07.并用TEM和XRD对粉体进行了表征.所制备的样品在1C倍率放电时电容量达到258mAh·g-1.     

纳米Ni(OH)2的控制结晶法制备

纳米Ni(OH)₂可以有效地提升镍氢电池的性能. 本文以NiSO₄和NaOH为原料, 聚乙二醇为分散剂, 采用控制结晶法制备了纳米Ni(OH)₂的胶体溶液, 控制结晶的pH值和温度分别为11.0 和45℃. 然后用正丁醇进行共沸蒸馏处理. 制备了分散性良好的纳米Ni(OH)₂粉体, 粉体颗粒粒径20nm左右, 团聚体系数为1.07. 并用TEM和XRD对粉体进行了表征. 所制备的样品在 1C倍率放电时电容量达到258mAh·g^-1.     

纳米二氧化硅的制备及表征

以水玻璃为原料,采用微乳液法和正丁醇共沸蒸馏法制备纳米级二氧化硅粉体.并通过扫描电镜,红外光谱分析,X射线衍射等手段对制备的纳米二氧化硅进行了表征.     

微乳液-共沸蒸馏法制备钛酸钡纳米粉体

以水/正辛烷/正己醇/司班80油包水体系中的微乳液滴为纳米反应器,通过微乳液滴中增溶的醋酸钡和油相中草酸酰化的钛酸四丁脂反应生成钛酸钡前驱体,并通过共沸蒸馏去除前驱体中的水分,以减小煅烧过程纳米钛酸钡粉体的团聚.实验结果表明,此方法制备的前驱体只需在550℃煅烧就可以生成钛酸钡晶粒,只需在600℃煅烧10min就可以得到粒径只有40nm左右的高纯立方钛酸钡纳米粉体,而且粉体具有粒度分布窄、形貌规则、优越的钛钡摩尔比、低团聚等优点.     

前驱体反应温度对CeO2粉体抛光性能的影响

以CeCl3为铈源,Na2CO3为沉淀剂,采用沉淀法在不同反应温度下制备CeO2前驱体,焙烧前驱体制备CeO2粉体,研究前驱体反应温度对产物组成、结构、形貌及抛光性能的影响。结果表明,当反应温度低于或高于50℃时,前驱体分别以Ce2(CO3)3·8H2O或CeCO3OH为主;反应温度对由2种前驱体制备的CeO2粉体的抛光性能影响较大,当前驱体反应温度为45~50℃时,制备的CeO2粉体粒度均匀,抛光性能最优。     

油页岩灰渣提取纳米α-Al_2O_3的方法研究

以油页岩为原料合成纳米α-Al2O3,采用表面活性剂超声辅助分散制备氢氧化铝前躯体,再用共沸蒸馏干燥的综合处理制备超细纳米氧化铝,并以共沸蒸馏法干燥,用XRD、TEM、BET进行分析,用热重/差热、红外、XPS进行表征,实验结果表明,所得的纳米氧化铝分散均匀,粒径为50-80nm,表面活性剂超声结合共沸蒸馏的方法对防止前躯体硬团聚很有效。     

Highly Efficient Photoelectrocatalytic Reduction of CO2 to Methanol by a p–n Heterojunction CeO2/CuO/Cu Catalyst

Photoelectrocatalytic reduction of CO2 to fuels has great potential for reducing anthropogenic CO2 emissions and also lessening our dependence on fossil fuel energy.Herein,we report the successful development of a novel photoelectrocatalytic catalyst for the selective reduction of CO2 to methanol,comprising a copper catalyst modified with flower-like cerium oxide nanoparticles(CeO2 NPs)(a n-type semiconductor)and copper oxide nanoparticles(CuO NPs)(a p-type semiconductor).At an applied potential of−1.0 V(vs SCE)under visible light irradiation,the CeO2 NPs/CuO NPs/Cu catalyst yielded methanol at a rate of 3.44μmol cm^−2 h^−1,which was approximately five times higher than that of a CuO NPs/Cu catalyst(0.67μmol cm^−2 h^−1).The carrier concentration increased by^108 times when the flower-like CeO2 NPs were deposited on the CuO NPs/Cu catalyst,due to synergistic transfer of photoexcited electrons from the conduction band of CuO to that of CeO2,which enhanced both photocatalytic and photoelectrocatalytic CO2 reduction on the CeO2 NPs.The facile migration of photoexcited electrons and holes across the p–n heterojunction that formed between the CeO2 and CuO components was thus critical to excellent light-induced CO2 reduction properties of the CeO2 NPs/CuO NPs/Cu catalyst.Results encourage the wider application of composite semiconductor electrodes in carbon dioxide reduction.     

Antibacterial and photocatalytic activity of ZnO nanoparticles from Zn(OH)2 dehydrated by azeotropic distillation,freeze drying,and ethanol washing

In this study, the antibacterial and photocatalytic activities of a series of ZnO nanoparticles (NPs) produced using different dehydration methods on as-prepared zinc hydroxide precipitates (Zn(OH)₂) have been investigated. Oven drying, azeotropic distillation, freeze drying, and ethanol washing methods were compared for their ability to yield non-agglomerated powders after precipitation synthesis. β-Zn(OH)₂ single phase was observed after ethanol washing, oven drying, and freeze drying procedures, while azeotropic distillation transformed β-Zn(OH)₂ into ZnO before calcination. Nanosized powders with high surface areas were produced via sublimation during the freeze drying process, and by replacement of hydroxyl groups on the precipitate surface with butoxy groups during azeotropic distillation. Both the photocatalytic degradation of Rhodamine B and the antibacterial activity against the pathogens Escherichia coli and Staphylococcus aureus were enhanced for dehydration methods that increased the surface area of ZnO NPs, suggesting that both photocatalytic and antibacterial behaviors were governed by similar mechanisms.     

介孔CeO2-ZrO2的制备及吸附水中Cr^6＋的研究

采用溶胶-凝胶法制备了CeO2-ZrO2介孔材料,研究了该介孔材料对水中Cr6＋的吸附性能,并通过小角XRD、大角XRD、TEM、N2吸附对介孔材料的表征分析了不同吸附条件对吸附性能的影响,结果表明,在室温下,较广的酸性范围内（pH=2-7）,吸附剂都能表现几乎相同的效果,吸附时间20min吸附几乎达到平衡,吸附量可达9.63mg·g^-1,去除率可达96.3%。     

Study on drying stage of nanoscale powder preparation

Nanoscale barium titanate powders of cubic phase were prepared by solprecipitation method following three kinds of drying stages: freeze drying, azeotropic distillation and oven drying. Freeze drying is the most effective procedure, though both freeze drying and azeotropic distillation stages are successful in preventing hard agglomerate formation and improving the sinterability of powder. The mechanism by which the drying stage prevents the formation of hard agglomerates was investigated.     

纳米粉体干燥方法的研究

采用三种干燥方法：冷冻干燥、共沸蒸馏和烘箱干燥对溶胶-沉淀法制备的沉淀进行干燥处理,得到了立方相BaTiO₃纳米粉．研究发现：冷冻干燥和共沸蒸馏都能防止粉体中形成硬团聚,提高了烧结活性,其中冷冻干燥法效果更明显．文章同时对两种干燥方法防止硬团聚形成的机理进行了讨论．     

Au-CeO_2纳米杂聚体颗粒的合成研究

在CeO2纳米立方体颗粒存在条件下,以丁基锂还原Au前体获得了Au-CeO2纳米杂聚体。采用TEM、HRTEM、STEM、EDS、XRD对纳米颗粒的形貌、结构及成分进行了分析。考察了实验条件对杂聚体形成的影响。结果表明,丁基锂适宜用作Au的还原剂,Au还原速度不能过快以保证Au在CeO2纳米颗粒表面能以多相成核方式形核长大。Au和Au-CeO2纳米颗粒浸渍γ-Al2O3后焙烧的实验表明,Au-CeO2杂聚体结构能有效抑制Au在高温下的凝聚长大。     

Cerium oxide dispersed multi walled carbon nanotubes as cathode material for flexible field emitters

Nanomaterials based electron sources are omnipresent in modern flat panel displays. Multi walled carbon nanotubes (MWNT) are the well studied electron emitter among the carbon materials. Since the surface modification of MWNT with low work function materials would have a positive impact on the field emission property of MWNT, cerium oxide (CeO2) nanoparticles dispersed multi walled carbon nanotubes (CeO2/MWNT) were synthesized by catalytic chemical vapour deposition followed by chemical reduction and its field emission property was investigated. The high-purity MWNT as well as CeO2/MWNT showed crystalline structure conformed by X-ray diffraction (XRD) and thermogravimetric analysis (TGA). Further characterisation was done with Raman spectroscopy, UV-Visible absorption spectra and Fourier transform IR spectroscopy (FT-IR). The morphology and structural details of CeO2/MWNT composite was probed by field-emission scanning electron microscopy (FESEM) and energy dispersive X-ray analysis (EDX). The direct evidence of the formation of CeO2/MWNT composites was given by transmission electron microscopy (TEM). The synthesized sample was coated over a flexible carbon paper using spin coating technique. The experiment was performed under a vacuum of 1 x 10(-6) Torr and Fowler-Nordheim equation was used to analyse the data. The turn-on voltage for the cerium oxide dispersed MWNT was found for a current density of 10 microA/cm2. The emission current density from the CeO2 nanoparticles dispersed MWNT reached 0.2 mA/cm2 at a reasonable bias field of 2.58 V/microm. The results were compared with those of pure MWNT and pure CeO2 nanoparticles with literature values.     

硬脂酸对CeO2纳米粒子的表面修饰研究

利用表面修饰法合成了硬脂酸修饰的 CeO2 纳米粒子,采用透射电子显微镜(TEM)观察了经表面修饰的CeO2 纳米粒子的形貌及分散性,并采用红外光谱(IR)、紫外可见分光光度计等对修饰的CeO2 纳米粒子进行了表征。结果表明:表面修饰剂硬脂酸与 CeO2 纳米粒子表面之间发生了化学键合作用;修饰后的CeO2 纳米粒子表面存在疏水有机基团,阻隔了 CeO2 纳米粒子的团聚,起到了分散作用;同时,修饰后的CeO2 纳米粒子在苯乙烯中的稳定性得到了提高。并且获得了硬脂酸的修饰量与CeO2 纳米粒子的最佳配比。