ZnO/ZnS异质结构纳米棒的制备及性能研究

本文利用低温二步水热法在ITO玻璃衬底上制备了ZnO/ZnS异质结构纳米棒,研究和比较了Zn O纳米棒和ZnO/ZnS异质结构纳米棒的形貌,结构和光学等特性。结果表明:未掺杂的ZnO纳米棒具有明显的六角结构表面,良好的晶体结构和c轴生长取向;ZnO/ZnS异质结构纳米棒的形貌和光学性质都发生了变化,纳米棒直径变化范围大,六角结构表面六边形不规则,且引入了较多的深能级缺陷。     

锌/铝/镧三元类水滑石的合成

采用恒定pH值共沉淀法制得锌/铝/镧水滑石化合物(Zn/Al/La-CO3-LDHs),并探索了各种合成条件(如pH值、不同锌铝镧摩尔比、陈化温度等)对合成产物形成的影响,用X射线衍射(XRD)、红外(IR)和粒度分析等手段对合成样品进行分析和表征,并对产品的热稳定性能给出了重要的结论。结果表明,当控制溶液中n(M2+)/n(M3+)为3:1,n(La3+)/n(Al3+)为0.25,pH值为10,在85℃水浴反应,65℃陈化20h,能合成出晶相结构完整的水滑石化合物Zn/Al/La-CO3-LDHs,合成的产物可以大大改善聚氯乙烯的热稳定性。     

The spatial distribution of Zn during galvanic corrosion of a Zn/steel couple

The spatial distribution of Zn²⁺ during galvanic corrosion of a model Zn/steel couple in 0.01 M NaCl was investigated using a scanning zinc disk electrode. The couple had a coplanar arrangement of a steel substrate with an electroplated zinc layer at the center. During galvanic corrosion, the marked changes in the Zn²⁺ concentration were confined to a thin solution layer ca. 1.0 mm thick above the couple surface. In this thin solution layer above the zinc layer, a higher concentration region of Zn²⁺ in the range of 5-18 mM extended around the zinc layer in the solution during galvanic corrosion. Conversely, above the steel surface distant from the zinc layer, the surface concentration of Zn²⁺ was almost zero during galvanic corrosion. On this surface, the precipitation of zinc corrosion products due to the hydrolysis reaction of Zn²⁺ was observed. The distribution of the Zn²⁺ concentration supported that Zn²⁺ acted as a buffer that suppressed the increased pH due to the cathodic reaction on the steel surface near the zinc layer and almost no corrosion products formed there. The spatial distribution of Zn²⁺ is discussed in relation to the distributions of potential and pH and the surface morphology of the galvanic couple.     

Impedance study of hydrogen evolution on Ni/Zn and Ni–Co/Zn stainless steel based electrodeposits

A study on the electrocatalytic performance of Ni/Zn and Ni–Co/Zn alloys for hydrogen evolution reaction (HER) in alkaline media (30 wt.% KOH solution) has been carried out. After preparing by electrodeposition on stainless steel supports, the alloys were leached of to remove part of the zinc and generate a porous layer. For the developed electrodes, the surface roughness factor, R_f, was evaluated by electrochemical impedance spectroscopy (EIS). The HER on these electrodes was evaluated by means of steady-state polarization curves and EIS. The obtained electrodes were characterized by large R_f for HER, and very low overpotentials at the current density of 250 mA cm⁻², η₂₅₀ ∼ 0.138 V at 30 °C. The high electrode activity was mainly attributed to the high surface area of the developed electrodes.     

Preparation and characterization of Zn18O/Zn16O isotope heterostructure thin films

An oxygen isotope-based heterostructure zinc oxide (ZnO) thin film, Zn¹⁶O/Zn¹⁸O/Zn¹⁶O, was made by pulsed laser deposition on an a-face sapphire substrate. The isotope-enriched Zn¹⁸O layer was made by irradiation of the isotope oxygen radical (¹⁸O^*). The isotopic ratio in the heterostructure film was analyzed via secondary ion mass spectroscopy (SIMS). The ratio of exchange from ¹⁶O to ¹⁸O was approximately 70% when the oxygen isotope was irradiated as a radical, while it was approximately 10% when the oxygen isotope was supplied as ¹⁸O₂ gas.     

DFT study of oxygen-bridged Zn2+ ion pairs in Zn/ZSM-5 zeolites

A cluster model for Zn/ZSM-5 zeolite is proposed, which consists of an oxygen-bridged [Zn–O–Zn]²⁺ moiety attached to two framework aluminum ions of two adjacent ZSM-5 5-rings. Its stability and catalytic activity in ethane dehydrogenation were considered using the DFT method and compared with those for single Zn²⁺ ions in the same rings. It is shown that the oxygen-bridged Zn²⁺ pair is rather reactive towards ethane dissociation and that the rate-limiting step is release of hydrogen.     

某铅锌矿尾矿及废石Pb、Zn释放规律实验研究

为研究铅锌矿废石和尾矿对环境的潜在影响和危害,采用静态浸出实验,研究了溶液pH值和温度对铅锌重金属离子溶出的影响;采用模拟降水动态淋滤实验方法,研究了不同酸度下,铅锌重金属离子随时间的溶出规律。结果表明,在模拟降水动态淋溶条件下,铅、锌离子都有一定的溶出浓度,离子溶出浓度随淋溶时间延长而降低;与Pb2+相比较,Zn2+的溶出受淋溶液pH值及淋溶时间的影响更大,对强酸性淋溶很敏感。     

我国Ca/Zn复合稳定剂的发展

综述了我国钙,锌（Ca/Zn）复合稳定剂的发展状况,介绍了Ca／Zn复合稳定剂的生产情况、主要生产厂家、生产能力、品种、性能、应用及研究进展和辅助稳定剂的研制情况,最后指出了Ca／Zn复合稳定剂今后的发展方向。     

Electrochemistry of Zn(II)/Zn on Mg alloy from the N-butyl-N-methylpyrrolidinium dicyanamide ionic liquid

Electrochemical reaction of Zn(II)/Zn on glassy carbon electrode(GC) and Mg alloy substrates was investigated in the room-temperature ionic liquid, N-butyl-N-methyl-pyrrolidinium dicyanamide (BMP-DCA) containing ZnCl₂ at 323 K. Amperometric titration experiments suggest that Zn(II) reacted with DCA anions forming [Zn(DCA)₃]⁻ complex anion, which also could be reduced to Zn metal via a single-step electron transfer process. By chronoamperometric measurements, the electrodeposition of Zn on GC and Mg alloy substrates involved three-dimensional instantaneous nucleation under diffusion control at 323 K. The Zn deposits are also systematically characterized by the techniques of powder X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The Zn layer deposited at a lower current density on Mg alloy substrates was more compact and uniform when compared to that deposited at a higher current density; consequently, this coating revealed a protection capability for the Mg substrate against corrosion.     

La/Zn/HZSM-5催化剂上的甲醇芳构化研究

Aromatization of methanol over co-impregnated La/Zn/HZSM-5 zeolite catalyst was studied.The selectivity of aromatics and BTX(benzene,toluene,and xylene)reached 64.0%and 56.6%,respectively,using La/Zn/HZSM-5 at 437°C,0.1 MPa and methanol WHSV(weight hourly space velocity)=0.8 h-1.Catalytic results showed that the La species was a very good promoter,increased selectivity of aromatics,and prolonged the catalyst lifetime on stream.The effects of the SiO2/Al2O3 ratio in zeolite,Zn and La loading,WHSV,reaction temperature, water content in the feed and H2 pretreatment of catalysts on the catalytic performance were studied in detail. Characterizations of the catalysts by thermogravimetric analysis(TGA),NH3-TPD(temperature programmed desorption),SEM(scanning electron micrograph),N2 adsorption-desorption,XRD(X-ray diffraction)and XRF (X-ray fluorescence),were carried out to understand the structure and discuss the aromatization performance of La/Zn/HZSM-5 zeolite catalyst.     

Suppression of NtZIP4A/B Changes Zn and Cd Root-to-Shoot Translocation in a Zn/Cd Status-Dependent Manner

In tobacco, the efficiency of Zn translocation to shoots depends on Zn/Cd status. Previous studies pointed to the specific contribution of root parts in the regulation of this process, as well as the role of NtZIP4A/B (from the ZIP family; Zrt Irt-like Proteins). Here, to verify this hypothesis, NtZIP4A/B RNAi lines were generated. Then, in plants exposed to combinations of Zn and Cd concentrations in the medium, the consequences of NtZIP4A/B suppression for the translocation of both metals were determined. Furthermore, the apical, middle, and basal root parts were examined for accumulation of both metals, for Zn localization (using Zinpyr-1), and for modifications of the expression pattern of ZIP genes. Our results confirmed the role of NtZIP4A/B in the control of Zn/Cd-status-dependent transfer of both metals to shoots. Furthermore, they indicated that the middle and basal root parts contributed to the regulation of this process by acting as a reservoir for excess Zn and Cd. Expression studies identified several candidate ZIP genes that interact with NtZIP4A/B in the root in regulating Zn and Cd translocation to the shoot, primarily NtZIP1-like in the basal root part and NtZIP2 in the middle one.     

Synthesis and characterization of Zn/Al and Pt/Zn/Al layered double hydroxides obtained by the sol–gel method

The influence of the nature of the Zn, Al and Pt precursors, and of the temperature of precipitation and aging have been studied in connection with the preparation of Zn/Al and Pt/Zn/Al layered double hydroxides (LDH) by the sol–gel method. Whatever the precursors the XRD analysis shows that LDH is formed at the expense of ZnO when the precipitation and aging temperatures decrease from 353 K to 273 K. Moreover, chemical composition and TG analysis suggest the presence of weak amounts of hydrozincite, hydrozincite-like and Al(OH)₃ phases. When the precursors are Zn acetate-2-hydrate or Al acetylacetonate the amount of LDH reaches a maximum of 50 mol% at 273 K. At variance, about 90 mol% of LDH is obtained when using Zn acetylacetonate and Al isopropoxide as precursors, which are precipitated at 273 K. This proportion is slightly improved for the Pt-containing sample prepared under the same conditions. The specific surface areas of the different samples obtained after calcination at 723 K increase with their LDH content, reaching values of 110–120 m² g⁻¹. They make them particularly attractive for catalytic applications.     

锌/富勒醇复合材料的制备及性能研究

制备了锌/富勒醇复合材料并研究了富勒醇对复合材料性能的影响.锌/富勒醇复合材料的制备分两步进行,其中包括电沉积制备富勒醇薄膜和电镀金属锌.采用辉光放电光谱法对富勒醇在镀层中的分布进行了表征.通过对锌/富勒醇复合材料硬度、耐盐雾腐蚀、交流阻抗谱和减摩性测试,分析了富勒醇对复合材料性能的影响.结果表明:富勒醇在锌/富勒醇复...     

镁铝及镁锌铝水滑石的合成与表征

采用共沉淀法合成镁铝及镁锌铝水滑石,并通过X射线衍射（XRD）、红外光谱（FT-IR）、扫描电镜（SEM）、热分析（TG/DTG）、粒度分析等手段对合成的水滑石进行表征,研究不同镁、铝、锌的投料比例对合成的水滑石结构及热性能等的影响。XRD表征结果表明,合成产物均具有水滑石特征峰。合成的镁铝水滑石随着镁铝比的增加其层板间距增大,层板上原子密度降低;合成的镁锌铝水滑石随着锌含量的提高层板间距减小,层板上原子密度降低。镁铝水滑石热分解过程有两个明显阶段,层间结晶水先脱除,随后是层间阴离子脱除及层板上部分羟基脱水;镁锌铝水滑石热分解过程只有一个明显的阶段,层板间阴离子在层板间结晶水脱除的同时也在脱除。     

Optimizing of a Zn/KOH/O2 cell with silver cathode

The effect of oxygen overpressure (300–600 mm Hg) of temperature (20–70°C) and electrolyte concentration (2–7N) upon the performance of a chemical cell of the Zn-oxygen type with silver cathode (gas electrode DSK type) has been studied. The dispersion analysis of data obtained from discharge curves using a variable resistor has been employed in testing the significance of the effect of varying the working parameters. The optimal values of working parameters have been obtained 6y optimization through a factorial experimental program: 400–500 mm Hg; 67–68°C and 5.9 N.     

纳米Zn/HZSM-5分子筛催化丙烷芳构化

采用低温老化、高温晶化两步法在Na2O-Al2O3-SiO2-四丙基氢氧化铵(TPAOH)-H2O体系中水热合成了纳米ZSM-5分子筛。用BET、N2吸/脱附曲线和NH3-TPD等手段对负载Zn的纳米HZSM-5分子筛结构和酸性进行了表征。结果表明,与微米Zn/HZSM-5分子筛催化剂相比,所制备的纳米Zn/HZSM-5催化剂比表面积明显增大,总酸量和弱酸量增加;在丙烷芳构化反应中,纳米Zn/HZSM-5分子筛具有更佳的催化活性、稳定性和芳烃选择性。     

聚合物/锡锌合金复合材料的密炼混合行为

研究了Sn Zn合金组成、含量、密炼工艺、以及聚合物基体对制备Sn Zn合金/聚合物复合材料过程中金属析出量的影响。结果表明,当Sn Zn合金组成一定时,合金添加量较低时,合金析出量为零,当合金添加量较高时,合金析出量随Sn Zn合金添加量增大而增大;增加Sn Zn合金中Zn含量,可减弱金属析出;与纯锡相比,Sn Zn合金与高密度聚乙烯（PE HD）有更强的复合能力;升高加工温度与降低Sn Zn合金中Zn的比例对于抑制金属析出具有等效性;合金析出量随密炼转速增大而增加,但转速增大会减小合金粒径分布;Zn质量分数为30 wt%的合金与PE HD密炼的最佳时间为35 min;提高聚合物极性,可减弱聚合物与Sn Zn合金复合时发生的金属析出。     

环保型钙/锌复合稳定剂中辅助稳定剂的发展

钙/锌复合稳定剂是为聚氯乙烯(PVC)无毒应用领域而开发的稳定剂.近年来,由于辅助稳定剂的广泛采用,该类稳定剂得到了前所未有的发展.评述了几种典型无毒辅助热稳定剂的发展现状、特点及稳定机理.     

无载体Fe／Zn超细粒子催化剂的磁学性质

根据铁的磁性特点，借助磁性测试方法，研究了ＦＴ合成Ｆｅ／Ｚｎ超细粒子催化剂的磁学性质，并考察了样品还原后磁学性质的变化，利用程序升温热磁还原法（ＴＰＲＭ）对样品在程序升温还原过程中磁性的变化进行了跟踪，发现锌对铁的还原行为有显著影响，锌对铁的还原有抑制作用，并能够稳定二价铁，使其不易被进一步还原到零价态，针对样品的超细粒子的特点，观察了其超顺磁现象。