Synthesis and growth mechanism of zirconia nanotubes by anodization in electrolyte containing Cl−

The formation and growth of a self-organized zirconia porous layer can be achieved directly by anodization of Zr in chloride containing electrolytes. The morphology of the porous layers is affected by electrochemical conditions such as Cl⁻ concentration. Zirconia nanotubes with diameters ranging from 250 to 300 nm and a length of 33 μm were formed under proper conditions. The nanotubes have smooth and straight walls. The composition of the nanotubes was characterized by using an energy dispersive spectrometer. Selected area electron diffraction investigation reveals that the as-anodized zirconia nanotubes have an amorphous structure. Crystal phase transition and structural stability of the ZrO₂ nanotubes after heat treatment were characterized. A possible growth mechanism is presented.     

One‐Step Electrodeposited Carbon Nanotube/Zirconia/Myoglobin Film for Direct Electron Transfer and Electrocatalysis

A nanobiocomposite film consisted of zirconia, multiwalled carbon nanotubes (MWNTs) and Myoglobin (Mb) was electrochemically deposited on the electrode. Direct electron transfer for the immobilized Mb was realized and high electrocatalytic efficiency toward H₂O₂ was observed. The proposed biosensor via a simple one‐step electrodeposition method displayed a broader linear range and a lower detection limit for H₂O₂, as compared with those CNT or ZrO₂ based biosensor. The linear range is from 2 × 10^?6 M to 1 × 10^?3 M with the detection limit of 6 × 10^?7 M. The present strategy provides a simple and effective method to assemble CNT, ZrO₂ and enzyme nanohybrid on the electrode and expands the scope of CNT‐based electrochemical devices.     

Applications of titania and zirconia hollow fibers in sorptive microextraction of N,N-dimethylacetamide from water sample

The convenient fabrications of titania and zirconia hollow fiber with three-dimensional porous structure using polypropylene hollow fibers as templates were developed. And an analytical method based on enrichment and extraction of analytes in the water sample, hollow fiber sorptive microextraction in combined with gas chromatography has been developed for the rapid analysis of N,N-dimethylacetamide (DMA) in the environmental samples. The results showed that zirconia hollow fiber gave higher extraction performance of DMA than that of titania hollow fiber. The method validations, including linearity, limit of detection, limit of qualification, precision, and repeatability were investigated. Linearity for six-point calibration curve was excellent with zirconia hollow fiber having r² value greater than 0.9993 at the linearity range of 0.001-1.0 mg mL⁻¹. In addition, it seems that hollow fiber sorptive extraction is a promising technique for the enrichment and purification of analytes extracted directly from liquid samples without any other pretreatment.     

Determination of melamine residues in milk products by zirconia hollow fiber sorptive microextraction and gas chromatography–mass spectrometry

News stories about the contamination of milk with melamine in China emerged on Sept 11, 2008, and the situation has since become an international health scare. In this work, a novel analytical method based on enrichment and pretreatment of analytes in the milk sample, hollow fiber sorptive extraction and gas chromatography–mass spectrometry has been developed for the rapid analysis of melamine in the dairy products. In the proposed method, melamine in the fresh milk was extracted by zirconia hollow fiber, enriching on zirconia coating of the hollow fiber, and then analyzed by GC–MS. The method validations including linearity, limit of detection, limit of qualification, recoveries at three different concentrations, precision, and repeatability were investigated. It was found that the proposed method provided linear range from 0.001 to 1000 μg/mL (r² = 0.9997), low detection limit of 0.001 μg/mL, and preferable recoveries at three different concentrations. The obtained results demonstrated that zirconia hollow fiber combined with GC–MS is a simple, rapid and solvent-free method for the analysis of melamine in the dairy products.     

Tunable electrical properties of self-organized zirconia nanotubes

Structural and electrical properties of self-organized zirconia nanotube layers can be tuned by a simple thermal treatment. The effect of F on the electrical conductivity of the MO_x nanotubes grown by anodization in fluoride-containing electrolytes is demonstrated.     

多钨酸盐修饰ZrO2气凝胶催化四氢呋喃开环聚合

采用过量浸渍结合溶剂蒸发将磷钨杂多酸(TPA)分散于ZrO₂气凝胶表面(TPA的质量分数为5%-45%), 再经750 °C空气气氛焙烧得到多钨酸盐修饰ZrO₂固体酸催化剂. 借助N₂吸附、X射线衍射(XRD)、傅里叶变换红外(FTIR)光谱、氨程序升温脱附(NH₃-TPD)和吡啶吸附红外(Py-IR)光谱对催化剂的结构及酸性质进行表征, 针对四氢呋喃(THF)开环聚合反应考察其酸催化性能. 研究发现, TPA与ZrO₂之间较强的相互作用抑制了ZrO₂的晶化, 同时也在一定程度上稳定了TPA的Keggin(凯金)-阴离子结构. 高温焙烧的催化剂中, 活性组分以ZrO₂锚定的表面相(包括含有畸变或缺陷型Keggin单元的杂多酸盐及以Zr为杂原子的类杂多酸物种等)和TPA完全分解形成的氧化物体相存在, 各物种的相对量取决于TPA的负载量. 催化剂表面同时具有中等强度的布朗斯特德(Brönsted)酸与路易斯(Lewis)酸中心, 且初始TPA负载量为20%的催化剂实现了活性组分在载体表面的单层覆盖, 因而显示最大的总酸量, 对THF聚合反应也表现出最高的催化活性. 在反应温度为40 °C、时间为20 h条件下, 聚合物收率达30.9%±2%, 数均相对分子质量为2698±100; 在催化剂重复使用6次过程中, 活性未见明显降低.     

用于苯选择加氢的Ru/Al2O3-ZrO2-NiO/堇青石蜂窝整体催化剂

使用浸涂法和氨气吸收沉积法制备了新型用于苯选择加氢的具有蛋壳型分布的Ru/Al₂O₃-ZrO₂-NiO/堇青石蜂窝整体催化剂,且在固定床整体反应器中对其性能进行了测试.该催化剂显示了较优的选择性和稳定性,并且在低的ZnSO₄浓度(0.5%问题)下环己烯产物收率可达24.7%.采用N₂吸附-脱附法,电感耦合等离子体发射光谱,光学显微镜,扫描电子显微镜及能量色散X射线光谱仪等技术研究了影响催化剂性能的因素.结果表明,NiO的引入减少了涂层中的微孔含量,有利于在低的添加剂浓度下提高环己烯选择性.ZrO₂的存在抑制了涂层的烧结,保证涂层在1373K高温焙烧后仍有较大的比表面积.Ru的蛋壳分布、薄的涂层厚度、较少的微孔含量、较大的比表面积和狭窄的孔分布可能是影响整体蜂窝催化剂中该特殊催化行为的重要因素.     

碱土金属氧化物改性ZrO2催化1,4-丁二醇选择性脱水合成3-丁烯-1-醇

采用浸渍法制备了碱土金属氧化物CaO,SrO或BaO改性的ZrO₂酸碱双功能催化剂,借助X射线衍射、低温N₂物理吸附、NH₃和CO₂程序升温脱附等手段表征了催化剂的结构、织构以及表面酸碱性质,并考察了其催化1,4-丁二醇选择性脱水合成3-丁烯-1-醇的反应性能.结果表明,碱土金属氧化物的引入显著调变了催化剂表面的酸性和碱性中心,进而对1,4-丁二醇转化率和3-丁烯-1-醇选择性产生重要影响.其中,CaO改性的ZrO₂样品中形成了大量的Ca-O-Zr结构,在ZrO₂表面形成大量碱性位点的同时,保持了较高的酸密度;而SrO和BaO改性的样品中生成了相应的锆酸盐,ZrO₂表面的酸密度呈现不同程度的下降.因此,CaO/ZrO₂催化剂表现出最优的催化活性和3-丁烯-1-醇选择性,350℃时,3-丁烯-1-醇收率最高,达60.5%.催化剂表面的酸碱协同作用是选择性合成3-丁烯-1-醇的关键因素.     

MnOx/ZrO2催化剂表面氧性能

采用ＸＲＤ，ＴＰＤ和ＴＰＲ等技术研究了ＭｎＯｘ／ＺｒＯ２催化剂的表面特性，结果表明，ＺｒＯ２表面的ＭｎＯｘ物种主要以Ｍｎ２Ｏ３和ＭｎＯ２形态存在，经还原－氧化处理后，ＭｎＯｘ物种的分散状况趋好。Ｍｎ－Ｚｒ之间的相互作用促进ＭｎＯ２的分解，而抑制Ｍｎ２Ｏ３的分解。