水热法合成纳米氧化铪及碳/氧化铪核壳结构纳米复合粉体的研究

Nano-sized HfO₂, C and C/HfO₂ powders obtained through hydrothermal process have been investigated by XRD, TEM and FTIR, and Different precursors, namely Hafnium(Ⅱ) oleate and Hafnium(Ⅱ) hydroxide derived from homogeneous precipitation method, have been chosen for the synthesis of nanometric HfO₂ via hydrothermal process. The results indicate that using the former material as the precursor under identically hydrothermal process can yield finer HfO₂ nanoparticles, compared to using the latter. Nano-sized Carbon of about 100 nm with square morphology and narrow size distribution can be obtained through hydrothermal reaction of sucrose solution at 200 ℃ for 6 h. The addition of as-synthesised Carbon nanoparticles into the hydrothermal process of HfO₂ powder can produce C/HfO₂ composite powders with core-shell structure.     

ICP-AES法测定氧化铪中12种杂质元素

建立了电感耦合等离子发射光谱法测定氧化铪中Al、Ca、Mg、Mn、Na、Ni、Fe、Ti、Zn、Mo、V、Zr等12种杂质元素的分析方法.方法的检测范围为0.004%～5%,标准偏差小于7%,加标回收率94%～103%,方法已用于常见样品分析.     

锆铪催化添加剂对PX液相氧化过程的影响

向对二甲苯(PX)催化氧化体系加入锆铪离子可有效地加速该反应过程．对锆铪离子与Co-Mn-Br催化剂体系的协同催化机理作了简要阐述，并对添加不同浓度下锆铪离子的催化作用进行了动力学实验．考察了添加锆和铪离子对主反应和燃烧副反应的影响，获得了锆铪离子添加剂对PX氧化过程的影响规律．研究发现，在实验所考察的温度与催化剂组成条件下，添加锆铪离子对反应过程中不同阶段的加速效果各不相同．且两种离子对燃烧副反应过程也有不同程度的加速作用．     

甲烷氧化菌素催化纳米金合成

甲烷氧化菌素(methanobactin,mb)是具有过氧化氢还原酶活性的荧光肽.从甲基弯菌Methylosinus trichospo-rium IMV3011限铜培养介质中分离mb,采用紫外可见全波长扫描法观察mb催化对苯二酚还原氯金酸合成纳米金的作用和影响,当mb/氯金酸/对苯二酚反应液中mb的浓度分别是2.5×10-5mol/L、5.0×10-5mol/L和1.0×10-4mol/L时,形成的纳米金溶液的特征峰分别是561.5 nm(OD561=0.158)、548.0 nm(OD5 48=0.426)、536.5 nm(OD5 36=0.541),特征峰波长减小,对应的吸光值增大,表明mb能够催化对苯二酚还原氯金酸合成纳米金,并且可以通过调控mb的浓度控制纳米金的合成量及粒径大小.     

Pt-Pb六边形纳米板电催化甲醇氧化反应中的表面元素分布效应

由于副产物CO可降低纯Pt催化剂的活性,因此双金属Pt基催化剂已经广泛用于提高直接甲醇燃料电池的性能.本文合成了Pt-Pb六边形纳米板,作为模型催化剂用于甲醇氧化反应(MOR),并通过乙酸(HAc)处理进一步控制纳米板表面Pt和Pb的分布,从而得到Pt-Pb合金表面均相分布的Pt-Pb纳米板以及非均匀分布的HAc处理的Pt-Pb纳米板.结果表明,与HAc处理的Pt-Pb纳米板相比, Pt-Pb纳米板的MOR催化活性和稳定性提高,这主要是由于亲氧性Pb的加入提高了CO容忍度并修饰了Pt的电子结构.     

Pt-Pb六边形纳米板电催化甲醇氧化反应中的表面元素分布效应（英文）

由于副产物CO可降低纯Pt催化剂的活性,因此双金属Pt基催化剂已经广泛用于提高直接甲醇燃料电池的性能.本文合成了Pt-Pb六边形纳米板,作为模型催化剂用于甲醇氧化反应(MOR),并通过乙酸(HAc)处理进一步控制纳米板表面Pt和Pb的分布,从而得到Pt-Pb合金表面均相分布的Pt-Pb纳米板以及非均匀分布的HAc处理的Pt-Pb纳米板.结果表明,与HAc处理的Pt-Pb纳米板相比, Pt-Pb纳米板的MOR催化活性和稳定性提高,这主要是由于亲氧性Pb的加入提高了CO容忍度并修饰了Pt的电子结构.     

聚丙烯腈/氧化石墨烯复合纳米纤维的制备与性能研究

以氧化石墨烯为添加物,采用静电纺丝的方法制备不同质量分数的聚丙烯腈/氧化石墨烯(PAN/GO)复合纳米纤维。使用扫描电镜(SEM)、透射电镜(TEM)对复合纳米纤维的微观结构进行观察;采用差示扫描量热仪(DSC)和热重分析仪(TGA)研究复合纳米纤维的热学性能随着氧化石墨烯添加量增加的变化;采用微机控制电子万能试验机对复合纳米纤维的力学性能进行研究。结果表明,加入氧化石墨烯后,纺制的PAN/GO纳米复合纤维会变细,但随着GO添加量的增多出现珠节现象,降低了纤维的粗细均匀度,同时加入GO后对PAN的氧化具有一定的抑制作用,而且GO的加入也使PAN的力学性能增加,当加入量为0.1%时断裂强力增加了一倍,但添加量为1%时,断裂强力又会降低,综合实验结果显示当加入氧化石墨烯的质量分数为0.1%时最适宜。     

阳极氧化水解法制备TiO2纳米膜

TiO2在光电化学电池领域已成为比较重要的半导体材料，自从1972年，Fuishima和Honda首次把TiO2电极用于光电解水以来，人们已经使用多种方法，如化学气相沉积、TiO2粉的烧结、RF射频溅射、等离子体喷涂或用胶体TiO2涂膜等各种方法，来制备单晶（金红石），多晶（金红石、锐钛矿     

Fe-50Cu纳米涂层的制备及氧化行为

为探讨晶粒尺寸变化对多相合金氧化行为的影响,采用磁控溅射技术制备了Ｆｅ－５０Ｃｕ过饱和固溶体纳米涂层,并利用热重实验对比研究了该涂层与同成分的铸态合金在８００℃空气中的氧化行为。结果表明,铸态合金中形成了包括铁和铜的氧化物及其复合氧化物在内的复杂外氧化膜,同时发生了铁的内氧化。涂层中发生了铁的单一外氧化,但涂层退化后,合金基体中仍出现铁的内氧化。这种氧化模式的转变机制在于涂层尺寸的纳米化显著扩展了     

聚乙烯吡咯烷酮/四氧化三铁复合纳米纤维的制备与表征

采用静电纺丝方法制备了聚乙烯吡咯烷酮/四氧化三铁复合纳米纤维, 并用透射电子显微镜(TEM)、X射线衍射(XRD)、热失重分析(TGA)和振动磁力分析进行了表征, 探讨了复合物的结构及其性能.     

Thermal Decomposition of Hafnium Phosphate and Related Materials

The thermal decomposition of hafnium phosphate (both in amorphous and crystalline forms), molybdate and tungstate was investigated. Hafnium phosphate has a layered structure, that of molybdate and of tungstate are tetragonal one. On investigating these materials two main endothermic processes with mass loss were observed in the temperature range of 298–1023 K. These processes were identified as crystal and structural water loss of the materials. The total mass loss of hafnium phosphate, molybdate and tungstate was 11,35 and 6.0%, respectively. In the case of mixed hafnium-titanium salts various crystal water quantities were found, depending on the titanium content of the sample. This revised version was published online in July 2006 with corrections to the Cover Date.     

负热膨胀材料研究进展

本文介绍了负热膨胀材料的制备技术、结构、性能、应用及热缩机理研究的主要进展。分析了负热膨胀材料合成及其应用中存在的主要问题,讨论了刚性单元模模型及其局限性,给出了热缩机理理论和实验特别是第一性原理声子谱计算和拉曼光谱研究的最新进展、存在问题及发展趋势。指出了负热膨胀材料研究中应重点解决的一些重要问题。     

Atomic Layer Deposition of Hafnium(IV) Oxide on Graphene Oxide: Probing Interfacial Chemistry and Nucleation by using X‐ray Absorption and Photoelectron Spectroscopies

Interfacing graphene with metal oxides is of considerable technological importance for modulating carrier density through electrostatic gating as well as for the design of earth‐abundant electrocatalysts. Herein, we probe the early stages of the atomic layer deposition (ALD) of HfO₂ on graphene oxide using a combination of C and O K‐edge near‐edge X‐ray absorption fine structure spectroscopies and X‐ray photoelectron spectroscopy. Dosing with water is observed to promote defunctionalization of graphene oxide as a result of the reaction between water and hydroxyl/epoxide species, which yields carbonyl groups that further react with migratory epoxide species to release CO₂. The carboxylates formed by the reaction of carbonyl and epoxide species facilitate binding of Hf precursors to graphene oxide surfaces. The ALD process is accompanied by recovery of the π‐conjugated framework of graphene. The delineation of binding modes provides a means to rationally assemble 2D heterostructures.     

Thermal Studies on Some Ionic Chelates of Hafnium(IV)

Ionic chelate complexes of kojic acid(I) and hafnium(IV) of the type [(η⁵-C₅H₅)₂HfL]⁺[MCl₃]^– (II)[HL=kojic acid; M=Zn(II), Cd(II), Hg(II), Cu(II)] have been synthesised and characterised by spectral studies (IR, UV, ¹H NMR and ¹³CNMR). Thermogravimetric (TG) and differential thermal analytical (DTA) studies have been carried out for these complexes and from the TG curves, the order and apparent activation energy for the thermal decomposition reactions have been elucidated. The various thermal studies have been correlated with some structural aspects of the complexes concerned. From DTA curves, the heat of reaction has been calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Hafnium Oxide Based Voltammetric Platform for the Sensitive Determination of Octopamine

An electrochemical sensor was constructed by modification of a glassy carbon electrode (GCE) with nanoparticles of hafnium oxide (HfO₂) and multi-walled carbon nanotubes (MWCNTs) for the sensitive determination of octopamine. The platform (HfO₂NPs/MWCNTs/GCE) presented an improved anodic peak for octopamine at 0.65 V. The combination of HfO₂ and MWCNTs resulted in outstanding catalytic activity and enhanced the magnitude of the peak response. Results suggest that a three-electron oxidation occurs for the process of octopamine. Voltammetry of octopamine exhibited a dynamic linear response in the concentration range of 1.6×10⁻⁶∼4.8×10⁻⁵ M with a detection limit of 5.4×10⁻⁷ M for octopamine.     

微波辅助合成石墨烯/氧化镍复合材料及其表征

本文通过微波辅助的方法,快速而有效地在热膨胀石墨烯(RG)的缺陷上原位合成氧化镍纳米颗粒,形成石墨烯/氧化镍复合材料(RG/NiO)。利用X-射线衍射(XRD),拉曼光谱(Raman),傅里叶变换红外(FTIR),扫描电镜(SEM),透射电镜(TEM),热重-差热(TGA-DSC)对所制备样品的结构、形貌和NiO含量在复合材料中的含量进行表征。结果表明,热膨胀石墨烯层数约7~8层,层间距约为0.35nm,缺陷多,在水热和微波处理后抗氧化性明显变差。复合材料中氧化镍颗粒平均粒径为25nm,均匀而密集地分散在石墨烯平面上,同时在复合材料中的含量为19.8%。     

微波辅助合成石墨烯/氧化镍复合材料及其表征

本文通过微波辅助的方法,快速而有效地在热膨胀石墨烯(RG)的缺陷上原位合成氧化镍纳米颗粒,形成石墨烯/氧化镍复合材料(RG/NiO)。利用X-射线衍射(XRD),拉曼光谱(Raman),傅里叶变换红外(FTIR),扫描电镜(SEM),透射电镜(TEM),热重-差热(TGA-DSC)对所制备样品的结构、形貌和NiO在复合材料中的含量进行表征。结果表明,热膨胀石墨烯层数约7~8层,层间距约为0.35 nm,缺陷多,在水热和微波处理后抗氧化性明显变差。复合材料中氧化镍颗粒平均粒径为25 nm,均匀而密集地分散在石墨烯平面上,同时在复合材料中的含量为19.8%。     

Model for the Thermal Expansion of Modified Graphite Nitrates

The thermal expansion of modified graphite nitrates was studied under close-to-equilibrium conditions. A model was proposed based on the expansion of a cavity in the sample similar to a Griffith crack. In accord with this model, the increase in the volume of the sample is proportional to the sixth power of the temperature due to the synergistic action of three factors: 1) accumulation of gas in the cavity, 2) increase in the temperature, and 3) decrease in the limiting pressure that the cavity can withstand without expanding.     

Bioanalysis by Immobilization of Antibodies on Hafnium(IV) Oxide with 3-Aminopropyltriethoxysilane

Self-assembled monolayers of 3-aminopropyltriethoxysilane (APTES) are commonly used to promote adhesion between substrates and organic or metallic materials with applications ranging from advanced composites to biomolecular lab-on-a-chip devices. In this work, the silanization on hafnium oxide (HfO₂) films is reported. The layers of HfO₂ were deposited on Si (001) substrates by atomic layer deposition. The grown HfO₂ films were modified in accordance with three main steps: oxidation, silanization, and cross-linking of the APTES monolayer using glutaraldehyde as cross-linking agent. Microscopic features were characterized by atomic force microscopy. Further, both bovine serum albumin and antibovine serum albumin agents were deposited on the samples to test their potential use as the immunosensor.     

Thermal Expansion Properties and Mechanochemical Synthesis of Stoichiometric Cocrystals Containing Tetrabromobenzene as a Hydrogen- and Halogen-Bond Donor

The solution and mechanochemical synthesis of two cocrystals that differ in the stoichiometric ratio of the components (stoichiometric cocrystals) is reported. The components in the stoichiometric cocrystals interact through hydrogen or hydrogen/halogen bonds and differ in π-stacking arrangements. The difference in structure and noncovalent interactions affords dramatically different thermal expansion behaviors in the two cocrystals. At certain molar ratios, the cocrystals are obtained concomitantly; however, by varying the ratios, a single stoichiometric cocrystal is achieved using mechanochemistry.