油酸包覆纳米铝粉/黑索今复合体系的热行为及非等温分解反应动力学

在氮气气氛下,采用油酸(OA)对纳米铝粉(nmAl)进行了表面包覆处理,采用扫描电镜(SEM)、X射线衍射(XRD)和傅里叶变换红外(FTIR)光谱对其形貌和结构进行了表征.用差示扫描量热(DSC)对油酸包覆前后的纳米铝粉与黑索今(RDX)构成的复合体系[nmAl/RDX和(nmAl+OA)/RDX]的热分解反应动力学进行了研究,得到了动力学参数和动力学方程.结果表明,大量油酸以物理吸附的方式吸附在纳米铝粉表面,少量油酸与纳米铝粉表面铝原子发生了化学反应,以化学键合的形式附着在纳米铝粉表面.与nmAl/RDX复合体系相比,(nmAl+OA)/RDX复合体系在不同升温速率下的分解峰峰温都相对降低,分解反应的表观活化能(Ea)和指前因子(A)分别为141.18kJ·mol-1和1012.57s-1,分解反应机理为三维扩散,服从n=1/2的Jander方程,其动力学方程为dα/dt=1013.35(1-α)2/3[1-(1-α)1/3]1/2e-16981.0/T.     

四氧化三铁包覆磷酸银复合光催化剂的可见光催化性能

利用沉淀法制备了四氧化三铁包覆的磷酸银高效可见光催化剂;采用X射线粉末衍射仪、固体紫外可见漫反射光谱仪及荧光光谱仪分析了催化剂的晶体结构和光学性质.与此同时,以光催化降解亚甲基蓝(MB)为探针反应,对催化剂的可见光催化性能进行了考察.结果表明,Fe3O4负载量为2%(质量分数)的复合催化剂对MB的降解率在60min时几乎达到100%;但随着Fe3O4负载量的增加,催化剂的光催化活性有所下降.     

碳包覆纳米铁镍磁性颗粒的合成

通过在双温控的化学气相沉积炉中热解四吡啶并卟啉铁镍混合物,合成了碳包覆铁镍纳米颗粒。原料中四吡啶并卟啉铁镍的质量比为7∶3;扫描电镜和透射电镜的结果显示碳包覆铁镍纳米颗粒形貌均匀,直径为100~300 nm;能谱结果显示碳包覆铁镍纳米颗粒是由铁、镍和碳组成;拉曼光谱证明产物有大量的缺陷存在,可能是由于球状结构上的碎片引起的;此外,磁性能测试表明室温下,碳包覆铁镍纳米颗粒有很高的饱和磁化强度,为56.3 emu·g^-1;而其产物的矫顽力趋近于零,呈超顺磁性,适合用于催化剂载体。     

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.     

氢氧化铝对纳米TiO2的表面包覆

氢氧化铝对纳米TiO2的表面包覆;纳米TiO2;氢氧化铝;包覆;光稳定性     

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。     

超细La2O3纳米粉末制备过程的电子显微镜动态观察

用超高压透射电子显微镜原位加热动态观察的方法研究从非晶氢氧化镧转变为纳米级氧化镧超细粉过程中显微组织和结构的变化。电子衍射花样证实在试样被加热到４００℃以上时转变为氧化镧纳米粉，其颗粒尺寸为２０￣５０ｎｍ。     

纳米镍在硝基苯加氢中催化性能的研究

纳米镍在硝基苯加氢中催化性能的研究左东华，张志琨，崔作林（青岛化工学院纳米材料研究所，青岛２６６０４２）关键词纳米镍，催化加氢，硝基苯．硝基化合物加氢还原是化工生产中的一个重要化工单元反应，现今工业生产中大多采用Ｒａｎｅｙ－Ｎｉ作为催化剂。但由于在Ｒ...     

碳纳米管负载纳米Ni修饰电极及碱液中电氧化甲醇

采用湿化学法在碳纳米管(MWCNTs)上负载Ni纳米粒子(MWCNTs-Ni),并制备MWCNTs-Ni修饰玻碳电极(MWCNTs-Ni/GCE),用X射线粉末衍射和透射电子显微镜测试技术对MWCNTs-Ni的物相和形貌进行了表征,通过循环伏安法研究了该修饰电极在碱性介质中的电化学行为以及对甲醇的电催化氧化作用。结果表明,面心立方的Ni纳米粒子均匀分散在碳纳米管表面,平均粒径约为16 nm,MWCNTs-Ni/GCE在碱性介质中的电化学行为是受扩散控制的准可逆过程,对甲醇的电催化氧化具有较高的电催化活性。     

碳纳米管上原位沉积钯-钴-镍纳米颗粒及其对乙醇氧化的电活性

以水合肼为还原剂,在水和乙醇的混合溶液中制备多壁碳纳米管(MWCNT)负载的纳米镍(Ni/MWCNT)和纳米镍钴(Ni-Co/MWCNT)颗粒,然后将它们分别与氯化钯溶液反应,形成的钯纳米颗粒原位沉积在MWCNT表面,从而得到MWCNT负载的Pd-Ni/MWCNT和Pd-Ni-Co/MWCNT催化剂。SEM和TEM图像显示,MWCNT上的催化剂颗粒是由5~10 nm的小颗粒团聚而成的30~100 nm的大颗粒,三金属催化剂的粒径比双金属的粒径小,在MWCNT上的分散度更高。ICP和EDS分析显示,Pd直接还原并包覆在纳米镍和纳米镍钴表面;采用循环伏安和计时电流技术,研究了催化剂在碱性溶液中对乙醇氧化的电催化活性,结果表明,Pd-Ni-Co/MWCNT催化剂对乙醇氧化具有强的电催化活性,乙醇氧化对应的峰电流密度达101.8 mA·cm^-2,并且催化剂催化活性稳定。     

聚合物粘结磁体用Nd—Fe—B微晶磁粉的氧化行为及防护

采用有机硅树脂、硅烷偶联剂和重铬酸盐处理快淬Ｎｄ－Ｆｅ－Ｂ微晶粉表面，通过热氧化增重试验２、湿热环境试验以及差示热分析法（ＤＴＡ）研究了上分的氧化行为和抗化效果，实验表明，上述方法能提高磁粉的抗氧化行为。     

Ni-Coated Diamond-like Carbon-Modified TiO2 Nanotube Composite Electrode for Electrocatalytic Glucose Oxidation

In this paper, a Ni and diamond-like carbon (DLC)-modified TiO₂ nanotube composite electrode was prepared as a glucose sensor using a combination of an anodizing process, electrodeposition, and magnetron sputtering. The composition and morphology of the electrodes were analyzed by a scanning electron microscope and energy dispersive X-ray detector, and the electrochemical glucose oxidation performance of the electrodes was evaluated by cyclic voltammetry and chronoamperometry. The results show that the Ni-coated DLC-modified TiO₂ electrode has better electrocatalytic oxidation performance for glucose than pure TiO₂ and electrodeposited Ni on a TiO₂ electrode, which can be attributed to the synergistic effect between Ni and carbon. The glucose test results indicate a good linear correlation in a glucose concentration range of 0.99–22.97 mM, with a sensitivity of 1063.78 μA·mM⁻¹·cm⁻² and a detection limit of 0.53 μM. The results suggest that the obtained Ni-DLC/TiO₂ electrode has great application potential in the field of non-enzymatic glucose sensors.     

6061铝合金微弧氧化陶瓷层生长速度的研究

以变形铝合金6061为试验材料,采用MAO240／750微弧氧化设备、TT260测厚仪和JSM6460扫描电子显微镜,研究了电流密度、占空比、样品尺寸和溶液温度等因素对铝合金微弧氧化陶瓷层生长速度的影响。结果表明：陶瓷层厚度随着时间的延长而线性增大,电流密度越大,陶瓷层生长速度越快,在相同时间内样品表面所达到的电压越高,电压的升高提高了陶瓷层被击穿继续发生内部氧化的能力;占空比大小对陶瓷层生长速度几乎无影响,而电压随着占空比的减小发生微小的上升;恒流氧化时,虽然陶瓷层的生长速度不随样品尺寸变化,但是电压随样品尺寸增大而升高;随着溶液温度的升高,溶液的导电能力增强,陶瓷层的生长速度变快。     

纳米金属粉对高氯酸铵热分解动力学的影响

The thermal decomposition characteristics of general ammonium perchlorate (g-AP) influenced by the addition of aluminum, nickel with different particle sizes (general and nano) are studied by TG and DSC. The results show that aluminum powders (both general and nano size) are nearly uninfluenced. Nano nickel powders have the greatest influence on the decomposition properties of g-AP among metal powders. Such accelerating effects of nanonickel powders are more apparent on the stage of high temperature decomposition than low temperature decomposition of g-AP and will be weakened with the decrease of the content of nanonickel. Nanonickel powders are also more effective than super fine nickel powders on accelerating the thermal decomposition of superfine AP (s-AP). The kinetic parameters of the thermal decomposition of s-AP and mixture of s-AP and nano nickel powders are obtained from the TG-DTG curves bythe integral method based on the Coats-Red fern equation. Nanonickel powders reduce the apparent activation energy of the thermal decomposition of s-AP from 157.9 kJ/mol to 134.9 kJ/mol. The most probable mechanism functions of the thermal decomposition reaction for s-AP and mixture of s-AP and nano nickel powders both belong to systems of Avrami-Erofeev equations. The mechanism of such accelerating effects has been discussed.     

Efficient Oxidation of Alcohols with Potassium Permanganate Adsorbed on Aluminum Silicate Reagent

Summary. A new reagent, potassium permanganate adsorbed on aluminum silicate, suitable for the oxidation of primary and secondary alcohols to the corresponding carbonyl compounds is described.     

置换法制备核壳结构Cu/Al复合粉末

在以明胶为保护剂、氟离子为络合剂的水溶液中, 采用Al粉直接置换还原铜盐的方法, 实现了纳米Cu在Al粉表面的快速化学沉积, 制备出核壳结构的Cu/Al复合粉末. 提出了置换反应的机理和历程, 探讨了反应的影响因素. 利用SEM, XRD, EDS, BET等测试手段对复合粉末进行了微观测试和表征. 结果表明: Al粉表面连续、均匀包覆了由晶粒大小约20 nm的Cu纳米颗粒组成的壳层.     

Synthesis of Nanocrystalline Zr3N4 and Hf3N4 Powders from Metal Dialkylamides

A simple process to synthesize Zr₃N₄ and nitrogen‐rich Hf₃N₄ powders via ammonolysis of metal dialkylamides, i.e. Zr(NEt₂)₄ and Hf(NEt₂)₄, at temperatures below 700 °C is presented. The obtained nitrides have a rhombohedrally distorted NaCl‐type structure, which has previously been reported only for nitrogen‐rich films of these nitrides. Regardless of the atmosphere (N₂ and He), the Zr₃N₄ starts to decompose above about ～ 650 °C and achieves the highest decomposition rate at about 900 °C, finally yielding the mononitride ZrN. Both Zr₃N₄ and Hf₃N₄ powders are nanocrystalline with the crystal size of about 2 nm.     

Ni纳米催化剂的制备及其对葡萄糖电催化氧化的研究

采用等体积浸渍和程序升温还原的方法制备了不同Ni含量的Ni/AC纳米催化剂,并对其进行了形貌和结构表征。采用三电极体系和循环伏安法在碱性溶液中进行了其对葡萄糖催化氧化的电化学测试。结果表明,Ni/AC/GCE(修饰在玻碳电极上的Ni/AC)催化剂对葡萄糖有较强的电催化氧化作用。其中,20%的Ni/AC/GCE对葡萄糖电催化氧化作用最强,且随着葡萄糖浓度增加,响应电流显著增大,二者呈线性相关。20%Ni/AC/GCE催化剂对葡萄糖催化氧化的线性响应范围为0.2~6.5 mmol/L,相关系数为0.999,响应灵敏度是13.15μA/(mmol/L),最低检测限为35μmol/L。稳定性测试结果表明,20%Ni/AC/GCE有着良好的稳定性,每隔两天测试,运行三周后其响应电流仍能维持在95%以上。     

Determination of Active Metal in Ultradispersed Iron Powders and TG Study of Their Oxidation

Two oxidation stages of electrolytic ultradispersed iron powder at the temperature range of 90–450°C have been stated. The contribution of increasing mass and evolving heat at the first oxidation stage due to changing Fe⁰ into Fe₂O₃ in the total oxidation effect is predominant. The thermal method of active metal determination in electrolytic iron powders has been developed. The coarse-grained reduced iron powder was not oxidized completely just to 900°C because of local sintering of big iron particles as a result of evolving heat at oxidation of high-dispersed iron particles. This revised version was published online in August 2006 with corrections to the Cover Date.     

Bi12 TiO20纳米粉体的制备及其光吸收特性研究

Nano-cystal Bi12 TiO20 powders have been prepared by the chemical solution decomposition（ CSD）method using bismuth nitrate and titanium butoxide as the starting precusors. The powders were characterized by the thermogravimetry and differential thermal analysis（TG-DTA）,X-ray diffractometry（XRD）and transmission electron microscopy（TEM）. The formation mechanism of Bi12TiO20 naocrystal has been analyzed. The UV-Vis diffuse reflectance spectra of the prepared Bi12TiO20 powders were measured to determine their optical absorption characteristic. The results showed that pure nano-crystal Bi12TiO20 powders could be easily prepared from stoichiometric precursor solutions at the annealing temperature 1550℃. A broad optical absorption band between 560-385 nm （about 2. 2-3. 22 eV）was observed for the prepared nano-crystal Bi12TiO20 powders.