电化学方法获得具有表面增强拉曼活性镍电极的研究

利用纯电化学手段获得了具有较强表面增强拉曼活性的镍电极, 改进了原有的镍电极表面预处理方法. 结果表明, 在0.5 mol/L的NaClO4溶液中, 结合电化学阶跃技术和循环伏安技术, 可以得到合适的粗糙镍电极; 同时, 还得到了探针分子吡啶在该粗糙镍电极表面随电极电位变化的表面增强拉曼光谱(SERS), 此时谱峰强度获得了极大的增强; 还研究了粗糙镍电极的扫描电子显微镜(SEM)图像, 并估算出其SERS增强因子约为104, 此结果比以前的镍电极表面粗糙方法所能达到的增强因子高一个数量级.     

Vanadium Doped Sol-Gel TiO2 Coatings

A study of the experimental conditions required to obtain vanadium doped sol-gel TiO2 coatings is presented. Tetraethyl orthotitanate was employed as the TiO2 source and VCl3, VOSO4 · H2O and VOSO4 dissolved H2SO4 where employed as vanadium sources.Dip coating has been used to produce coatings on silicon wafers, spectral carbon electrodes and titanium electrodes. Both supported and unsupported films have been studied by UV-Vis spectra, IR spectroscopy and X-ray diffraction (XRD). The measurements have been made on samples as prepared and treated thermally at temperatures between 100°C and 300°C. The thermal treatment temperatures have been established from DTA/TGA measurements.The vanadium doped sol-gel TiO2 coatings have been tested as sensors for redox potential measurements in electrochemical processes. The influence of both the thickness of films and the nature of substrate has been investigated.     

The influence of the mercury and thallium atoms in organomercury and organothallium nitroxyl radicals on their reactivity

An increase is found in the reactivity of organomercury and organothallium nitroxyl mono- and biradicals of the imidazoline type in comparison with the analogous compounds without organometallic fragments. This is explained by the formation of coordination bonds NHg, NTl, and NOHg.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 1, pp. 224–226, January, 1993.     

ZnO纳米线的电化学制备研究

High-quality ZnO nanowires have been synthesized at relatively low temperature via one-step electrochemical anodization technique. In this method, Zn sheet acted as the anode and Pb sheet served as the counter electrode, and the complex solution of HF-C₂H₅OH-H₂O was used as electrolyte. ZnO nanowires were characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Transmission Electron Microscopy (TEM) and Selected Area Electron Diffraction (SAED) and X-ray Diffraction (XRD). The results show that the nanowires were wurtzite crystalline ZnO, and the ZnO nanowires with the diameters of 70 nm and 30～40 nm were obtained by adjusting preparation conditions, respectively.     

Cooperation of reducing species for NO reduction over Ag/Al2O3 under oxidizing conditions

Summary The cooperation effect of reducing species for selective reduction of NO over Ag/Al₂O₃ has been investigated in the presence of excess oxygen. When the combinations of propene or propane and ethanol or methanol were used as reducing agents, NO reduction took place over a wider temperature range, compared with a single hydrocarbon as reducing agent.     

Reduction of Chemical Reactions in Nitrogen and Nitrogen–Hydrogen Plasma Jets Flowing into Atmospheric Air

The large number of possible chemical reactions represents a severe burdenfor modeling of even relatively simple plasma systems. Reduced sets ofchemical reactions have been obtained for numerical simulations of nitrogenand nitrogen-hydrogen plasma jets flowing into an atmospheric airenvironment. The important or active reactions are determined based on asimplified reduction method. A reaction is considered active if it leadsto higher sensitivities than a specified cutoff sensitivity of 1%. Theactive reactions exert a significant influence on main plasma parameters,such as velocity, temperature, and species concentrations. The sensitivityanalysis for the specified systems shows that two NO reactions, known asZel'dovich reactions (N₂+ONO+N andNO+OO₂+N),⁽¹⁾ are both active in a nitrogenplasma jet. On the other hand, the latter is not active and may be omittedin a nitrogen–hydrogen plasma jet. A nitrogen–hydrogen plasmajet requires contribution of two active charge exchange reactions:N₂+N⁺N⁺ ₂+N andN+H+N+ +H, while only the former is needed in a nitrogen plasmajet. The dissociation reactions are all active in both plasma jets, exceptthe dissociation of OH.     

Linear silver clusters in aqueous solution (clusterites): radiation-induced chemical synthesis and properties

The formation and properties of the products of the radiation-induced chemical reduction of silver ions in aqueous solutions containing sodium polyacrylate were investigated. The absorption spectra of these species exhibit a band at 290 mn and a band in the visible region. The latter shifts from 470 nm to -800 nm with time or after the addition of silver ions. The species obtained (clusterites) arc linear silver clusters bound to the carboxyl groups of the ion exchanger. The red shift of the visible band is due to the increase in their size. The mechanism of the formation and the structure of the clusterites are discussed.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1429–1435, June, 1996.     

新的聚合物支载硼氢负离子还原剂系统研究 3: 聚合物支载还原剂III

硼氢化钠的低分子还原系统研究很多,但其聚合物支载还原剂相对来说就很少,而且仅以强碱型阴离子交换树脂来制备的聚合物试剂。为了寻找用途更广泛的、新的聚合物支载还原剂,我们进行了硼氢负离子的聚合物还原系统的研究;发现能用弱酸型阳离子交换树脂制备出新的聚合物支载还原剂。前文报道了用NaBH_4的水溶液和阴离子交换树脂     

Determination and fractionation of sulphur in a contaminated dredged sediment

Conversion of sulphur compounds in reduced, contaminated sediments that are brought in upland conditions may largely affect the potential mobility of heavy metal contaminants. We applied selected methods for the determination of total sulphur and sulphur fractions in a contaminated sediment in the reduced state and after gradual drying and oxidation during 1 month. Dry ashing, followed by ion chromatographic detection, was reliable for the determination of total sulphur. Good recoveries were obtained in both reference samples and spiked samples. Total sulphur was 14.5±0.6 g kg⁻¹ relative to dry sediment. Wet chemical methods that involve the determination of acid-volatile, Zn–HCl-reducible, chromium-reducible, acetone-soluble and HI-reducible sulphur were used to estimate specific sulphur forms. Results for acetone-soluble sulphur were to high and not consistent with results for other fractions. Major part of sulphur in the sediment (90%) was inorganic. Sulphides were converted partially to sulphate and to intermediary oxidised sulphur compounds upon oxidation of the sediment. The results suggested that the intermediary oxidised sulphur pool in the reduced sediment (2.5 g kg⁻¹) mainly consisted of pyrite, that was not converted during drying and oxidation. No significant changes in organic sulphur were detected.     

CVD Reactions of TiCl4 with Ammonia： a Quantum Chemical Study

Based on density functional calculations, the mechanism and the energetic course of the chemical vapor deposition （CVD） reaction of TiCl4 with NH3 were studied at the level of B3LYP with 6-311g（d） basis set. Furthermore, the polymerization processes of dimerization, trimerization and tetramerization were investigated. The calculation results indicate that the formation of polymers is favored at the elimination reaction. On the basis of the calculated energetics, a possible mechanism of the reduction reaction has been proposed.