PAn/DMcT复合膜电极的电化学性能

PAn/DMcT复合膜电极的氧化还原峰电位差和电化学阻抗比DMcT的小得多,这表明PAn对DMcT具有电催化性能,使DMcT的氧化还原反应速度大大提高.而且DMcT使几乎所有的PAn都能保持电化学活性,复合膜电极的CV曲线经过100次循环几乎没有变化.PAn/DMcT复合膜电极的首次充放电比容量分别为275mAh·g-1和200mAh·g-1,首次充放电效率为72.7%.和粉末混合法制备的复合膜相比,溶液法制备的PAn/DMcT复合膜电极具有较高的放电比容量和优良的循环稳定性.     

聚{(3-乙酰基)吡咯-[2,5-二(对丁氧基苯甲烯)]}的合成与表征

合成了一种新型含有推-拉电子基团的聚吡咯衍生物——聚{(3-乙酰基)吡咯-[2,5-二(对丁氧基苯甲烯)]}(PA-PDBOBE)。通过红外光谱(FT-IR)、核磁共振(1H-NMR)、紫外光谱(UV-Vis)、热重分析(TG)和循环伏安(CV)测试等分析手段对聚合物结构和性能进行了分析。UV-Vis谱表明,PAPDBOBE的光学禁带宽度(Eg)为1.51 eV。该聚合物的TG谱显示聚合物的热分解温度为165℃。循环伏安特性曲线(CV)表明,该聚合物膜电极在LiClO4乙腈溶液中-1 V～1 V的电压间有氧化还原反应,其氧化还原反应的峰电位分别为0.52 V和-0.51 V。     

水溶性C_(60)-环糊精包络化合物的合成及其光、电化学性质研究

以羟丙基-β-环糊精为主体,C60为客体形成了C60-羟丙基-β-环糊精包络化合物,并对包络化合物进行了红外和紫外光谱的表征。通过循环伏安法研究了包络化合物在水溶液中的电化学性质,发现其在电极上的反应是准可逆的氧化还原反应。在紫外光光照条件下形成了C.-60-羟丙基-β-环糊精,利用它的还原性对Ag+和AuCl-4等进行了还原,形成了水溶性的Ag和Au纳米颗粒,并对其进行了透射电镜和紫外可见光谱表征。     

镍-磷-碳-氧化学镀层的制备、表征及1,4-丁炔二醇在体系中的作用

以铜片为基体,采用中心组合规则得到优化的化学镀镍-磷工艺配方.在优化的配方中加入一定量的1,4-丁炔二醇(BOZ),所得镀层表面形貌及组成结构用扫描电镜与X射线衍射仪进行表征,得到了光亮的Ni-P-C-O镀层,镀层硬度高,耐酸蚀性强;探讨了BOZ在反应体系中的作用机理.结果表明,BOZ不仅是光亮剂,而且参与该体系的氧化还原反应,BOZ分解反应的宏观动力学表现为准一级;当BOZ的初始含量为60～123 mg/dm3时,其参与氧化还原的量与温度和初始浓度呈正相关性,温度起主导作用;当BOZ的初始含量为123～240 mg/dm3时,其参与氧化还原的量与温度和初始浓度呈负相关性,浓度起主导作用.     

AMPS稳定的有机硅丙烯酸酯无皂乳液共聚合研究

以过硫酸钾/亚硫酸氢钠为氧化还原体系,合成了由表面活性单体2-丙烯酰胺基-2-甲基丙磺酸钠(AMPS)稳定的硅丙无皂乳液.考察了表面活性单体用量、反应温度、以及有机硅加入顺序等对乳液聚合和乳液性能的影响.当有机硅先加时由于生成大量凝胶反应无法顺利进行;有机硅后加可以得到稳定的硅丙乳液.采用红外光谱分析表明,有机硅氧烷与丙烯酸酯发生了共聚反应.有机硅的加入使共聚物的耐水性、耐热性提高.     

聚｛（3-乙酰基）吡咯-[2,5-二（对辛氧基苯甲烯）]｝的合成与表征

合成了一种新型含有推-拉电子基团、可溶性的聚吡咯衍生物-聚{（3-乙酰基）吡咯-[2,5-二（对辛氧基苯甲烯）]}（PAPDOOBE）。并通过FT-IR、1 H NMR、UV-Vis、TG和CV等分析手段对聚合物结构和性能进行了分析。UV-Vis谱表明PAPDOOBE的光学禁带宽度（Eg）为1.44eV。循环伏安特性曲线（C-V）表明,该聚合物膜电极在0.1mol/L LiClO4的乙腈溶液中、-1～1V的电压间存在氧化还原反应;在100mV/s的扫描速率下,其氧化还原反应的峰电位分别为-0.21和-0.53V。该聚合物的TG谱显示聚合物的热分解温度为168℃。     

CexPr1-xO2-δ复合氧化物的制备、表征及CO和CH4氧化性能研究

采用溶胶-凝胶法制备了CexPr1-xO2-δ复合氧化物,用XRD和Raman光谱对复合氧化物的体相和表面结构进行了表征.结果表明,当x≥0.5时Pr离子完全进入CeO2晶格中形成单一立方相固溶体.CexPr1-xO2-δ(x＞0.3)复合氧化物在465和1150cm-1附近出现具有CaF2结构的Raman特征峰,和由氧空穴引起的不对称振动产生的570和195cm-1Raman谱峰.固溶体的形成使还原温度降低,提高了复合氧化物的还原性能.CO氧化活性表明氧空穴的存在对CO氧化活性有一定的对应关系;而CH4氧化活性则与还原温度和强度有关.     

医药中间体5-氨基-2,4,6-三碘异酞酸的合成研究

以5-硝基-异酞酸为原料,通过还原、碘取代反应,生成5-氨基-2,4,6-三碘异酞酸.重点对碘取代反应中反应介质、碘化剂的选取及碘化剂用量、反应温度、反应时间等参数及精制方法对反应得率影响进行了讨论,确定了最佳配方和工艺条件.     

2-[(8-羟基喹啉)-2-基]-5-(2-噻吩基)[60]富勒烯吡咯烷的合成、光学及电化学性能

通过1,3-偶极环加成反应合成出2-[(8-羟基喹啉)-2-基]-5-(2-噻吩基)[60]富勒烯吡咯烷,利用UV-Vis、FT-IR、RAMAN、MALDI-TOF MS、1 HNMR、13C NMR等手段对产物的结构进行了表征,并研究了产物的光学及电化学性能。结果表明,相对于C60来说,该产物的紫外吸收波长及荧光发射波长均发生红移,各对氧化还原峰的半峰电位发生明显的负移,更有利于应用于光电转化领域。     

N+离子注入聚(2-甲氧基-5-辛氧基)对苯乙炔薄膜的微观结构

通过双醚化反应、氯甲基化反应以及在强碱性条件下进行的脱氯化氢反应,制备出新型光电功能材料聚(2-甲氧基-5-辛氧基)对苯乙炔(PMOCOPV).采用能量为30 keV,剂量为1.2×1016 ions/cm2～4.8×1017 ions/cm2的氮离子(N )对PMOCOPV进行离子注入改性.红外光谱研究表明,离子注入改性后的PMOCOPV,在3433 cm-1和1622 cm-1处出现N-H的振动吸收峰;随着N 注入剂量的增加,PMOCOPV在紫外和可见光区域的吸收增强,且吸收边向长波方向移动;离子注入使PMOCOPV的分子链排列更加规整,取向度明显增加,结晶性能大大改善;离子注入后PMOCOPV的起始分解温度由未注入时的200 ℃提高至360 ℃,材料的热稳定性能显著增强.     

Anion effects on the electrochemical regeneration of Ce(IV) in nitric acid used for etching chromium

The anion impurities such as SO4(2-), Cl(-), and Cr2O7(2-) commonly present in the spent (hazardous) Cr-etch solutions from color filter manufacturing processes may influence the solutions' regeneration by the electrooxidation of Ce(III) to Ce(IV). This study, therefore, investigated the effects of these anions on Ce(III)/Ce(IV) redox reactions at glassy carbon in HNO3. In cyclic voltammetric tests, the presence of SO4(2-) decreased the formal potential but increased the peak potential separation (Delta Ep) of Ce(III)/Ce(IV) couple, and lowered the peak current for Ce(IV) reduction whereas Cl(-) did not change the formal potential and Delta Ep, but the peaks for Cl(-) and Ce(III) oxidation partially overlapped. Cr2O7(2-) slightly lowered the peak current for Ce(III) oxidation but significantly decreased that for Ce(IV) reduction. The Tafel slope for Ce(III) oxidation was approximately 65mVdecade(-1) in the absence of anion impurities. Increasing SO4(2-), Cl(-), or Cr2O7(2-) in solution raised the Tafel slope. The Ce(III)/Ce(IV) equilibrium potential decreased with the increase of SO4(2-) or Cl(-) but was hardly influenced by Cr2O7(2-) addition. These observations from individual anion species together well explained the anions' co-effect (kinetic hindrance) on the Ce(III) oxidation in HNO3, revealing that these anions are unfavorable for the electrooxidation of Ce(III) in the spent Cr-etch solutions.     

Nanostructured H(3+x)PW(12-x)NbxO40 (x = 0-3) Keggin heteropolyacid catalysts

Nanostructured H(3+x)PW(12-x)NbxO40 (x = 0, 1, 2, 3) Keggin heteropolyacid (HPA) catalysts were investigated by scanning tunneling microscopy (STM) and tunneling spectroscopy to probe their redox property and oxidation catalysis. STM image showed that the HPAs formed two-dimensional well-ordered monolayer arrays on graphite surface. In tunneling spectra of the HPAs deposited on graphite, they exhibited a distinctive current-voltage behavior referred to as negative differential resistance (NDR). NDR peak voltage measured atop HPA molecule was then correlated with reduction potential and absorption edge energy determined by electrochemical method and UV-visible spectroscopy, respectively. It was revealed that NDR peak voltage of the HPAs appeared at less negative voltage with increasing reduction potential and with decreasing absorption edge energy. In order to correlate NDR peak voltage of H(3+x)PW(12-x)NbxO40 Keggin HPAs with oxidation catalysis, oxidative dehydrogenation of isobutyraldehyde to methacrolein was carried out as a model reaction. NDR peak voltage of the HPAs appeared at less negative voltage with increasing yield for methacrolein.     

Scanning tunneling microscopy study of nano-structured polyatom-substituted H4PW11M1O40 Keggin and H7P2W17M1O62 (M = Nb, Ta) Wells-Dawson heteropolyacid catalysts

Polyatom-substituted H4PW11M1O40 Keggin and H7P2W17M1O62 (M = Nb, Ta) Wells-Dawson heteropolyacid (HPA) catalysts were investigated by scanning tunneling microscopy (STM) and tunneling spectroscopy to elucidate their redox property and oxidation catalysis. STM images clearly showed that HPAs formed nano-structured monolayer arrays on graphite surface. In tunneling spectroscopy, HPAs exhibited a distinctive current-voltage behavior called negative differential resistance (NDR). NDR peak voltage of the HPAs was then correlated with reduction potential determined by electrochemical method in solution. NDR peak voltage of the HPAs appeared at less negative voltage with increasing reduction potential. Vapor-phase oxidative dehydrogenation of isobutyraldehyde to methacrolein was also carried out as a model reaction to probe oxidation catalysis of the HPAs. NDR peak voltage of the HPAs appeared at less negative voltage with increasing yield for methacrolein. NDR peak voltage could be utilized as a correlating parameter for the reduction potential and as a probe of oxidation catalysis in the oxidative dehydrogenation of isobutyraldehyde.     

Synthesis and optoelectrochemical properties of ZnS:Mn nanocrystals

Mn2+ ions doped ZnS semiconductor nanocrystals (ZnS:Mn NCs) were synthesized using colloidal chemical method at 70 degrees C without any capping agents. The as-prepared undoped ZnS and ZnS:Mn NCs were characterized by UV-Vis absorption spectra, fluorescent emission spectra, X-ray powder diffraction (XRD), inductively coupled plasma analysis (ICP), X-ray photoelectron spectroscopy (XPS), Dynamic light scattering (DLS), cyclic voltammogram and electronic transmission microscopy (TEM). The dependence of photoluminescence of ZnS:Mn NCs on dopant concentration was studied. The results show that Mn2+ ions mainly stay at ZnS nanocystal surface, and Mn2+-surface defect state complex was formed, as a result of which, surface defect emission of ZnS nanocrystals was substituted with Mn2+-related PL emission. The strongest fluorescent emission intensity was obtain at 1.85 at% Mn2+ doped ZnS:Mn NCs. The Mn2+ doped ZnS:Mn NCs are of 5 nm in diameter. The emission peak at 575 nm is attributed to d-d (4T1 --> 6A1) transition of Mn2+ ions. The existence of Mn2+-related photoluminescence could be well correlated with cyclic voltammogram of Mn2+-doped NCs, where pair of oxidation and reduction peaks were clearly observed due to the doped Mn2+ ions. The adsorbed Mn2+ ions on ZnS NCs produced neither Mn2+ emission nor redox peaks. For heavily doped ZnS:Mn NCs (4.87 at%), redox peaks gap in cyclic voltammogram became larger and new oxidation peak appeared. Correspondingly, when the Mn2+ doping concentration reached 4.87 at%, the Mn2+-related emission totally disappears due to the Mn-Mn interactions. This work implys that electrochemical technique is possibly an useful tool to probe the local structure of doped Mn2+ ions.     

Voltammetric procedure for examining DNA-modified surfaces: quantitation, cationic binding activity, and electron-transfer kinetics

To examine DNA-modified surfaces, we have developed a simple, convenient, and reliable procedure based on the voltammetric response of multiply charged transition metal cations (such as [Ru(NH3)6]3+) bound electrostatically to the DNA probes. At micromolar concentrations of the redox molecules in the electrolyte, the reduction and oxidation waves resulting from the immobilized cations on DNA-modified electrodes are well defined, stable, and reproducible. The surface densities of both single- and double-stranded oligonucleotides were accurately determined by integration of the peak for reduction of [Ru(NH3)6]3+ to [Ru(NH3)6]2+. In addition, the binding constant and electron-transfer rate constant of [Ru(NH3)6]3+ on DNA-modified electrodes were evaluated with the help of classical models. The present research provides not only an applicable and simple protocol for the quantitation of DNA probes on chips but also a versatile and powerful tool for the investigation of the binding activity and electron-transfer kinetics of cationic analytes on DNA-modified surfaces.     

Electrochemical treatment of Procion Black 5B using cylindrical flow reactor--a pilot plant study

The paper presents the results of an efficient electrochemical treatment of Procion Black 5B--a pilot plant study. Experiments were conducted at different current densities and selected electrolyte medium using Ti/RuO2 as anode, stainless-steel as cathode in a cylindrical flow reactor. By cyclic voltammetric analysis, the best condition for maximum redox reaction rate was found to be in NaCl medium. During the various stages of electrolysis, parameters such as COD, colour, FTIR, UV-vis spectra studies, energy consumption and mass transfer coefficient were computed and presented. The experimental results showed that the electrochemical oxidation process could effectively remove colour and the chemical oxygen demand (COD) from the synthetic dye effluent. The maximum COD reduction and colour removal efficiencies were 74.05% and 100%, respectively. Probable theory, reaction mechanism and modeling were proposed for the oxidation of dye effluent. The results obtained reveal the feasibilities of application of electrochemical treatment for the degradation of Procion Black 5B.     

Room temperature redox reaction by oxide ion migration at carbon/Gd-doped CeO2 heterointerface probed by an in situ hard x-ray photoemission and soft x-ray absorption spectroscopies

Abstract

In situ hard x-ray photoemission spectroscopy (HX-PES) and soft x-ray absorption spectroscopy (SX-XAS) have been employed to investigate a local redox reaction at the carbon/Gd-doped CeO₂ (GDC) thin film heterointerface under applied dc bias. In HX-PES, Ce3d and O1s core levels show a parallel chemical shift as large as 3.2 eV, corresponding to the redox window where ionic conductivity is predominant. The window width is equal to the energy gap between donor and acceptor levels of the GDC electrolyte. The Ce M-edge SX-XAS spectra also show a considerable increase of Ce³⁺ satellite peak intensity, corresponding to electrochemical reduction by oxide ion migration. In addition to the reversible redox reaction, two distinct phenomena by the electrochemical transport of oxide ions are observed as an irreversible reduction of the entire oxide film by O₂ evolution from the GDC film to the gas phase, as well as a vigorous precipitation of oxygen gas at the bottom electrode to lift off the GDC film. These in situ spectroscopic observations describe well the electrochemical polarization behavior of a metal/GDC/metal capacitor-like two-electrode cell at room temperature.     

Balancing redox activity allowing spectrophotometric detection of au(i) using tetramethylbenzidine dihydrochloride

Aqueous, acid solutions containing balanced amounts of a strong reductant (formaldehyde, HCHO) and a strong oxididant (N-bromosuccinimide, NBS) allow the first sensitive spectrophotometric analysis of monovalent gold ion, Au(I), using oxidation of color reagent 3,3',5,5'-tetramethylbenzidine dihydrochloride (TMB). This new method enables various oxidation states of Au ion to be quantified by balancing reduction potential in a Au solution. At low reductant levels, NBS oxidizes Au(I), which linearly suppresses subsequent oxidation of TMB by NBS to its blue charge-transfer complex of diamine and diimine to 2.00 mg L(-1) of Au, resulting in reduced color formation. The linear range of Au(I) quantitation was increased substantially relative to existing methods: from 0.005 to 1.00 mg L(-1) (R(2) = 0.988). For this range, the limit of detection was 0.0025 mg L(-1), which is comparable to the best reported spectroscopic method to analyze Au(III). At relatively high reductant levels, Au(I) is reduced to Au(0), then subsequently oxidized from Au(0) to Au(III) by addition of NBS. TMB is oxidized to its blue charge-transfer complex via the reduction of the reoxidized Au(III) to Au(0). Balancing redox conditions of HCHO/NBS at a molar ration of 22.7 allows quantitative measurement of Au(I) across a linear concentration range of 0.05-2.00 mg L(-1) (R(2) = 0.997). This balancing redox condition could allow sensitive, quantitative, spectrophotometric analysis of other metal ions besides Au by targeting the metal ion's reduction potential with an associated redox-sensitive color reagent.     

A model for fitting peaks induced by fast neutrons in an HPGe detector

Inelastic neutron scattering in the HPGe detector produces wide, triangular-shaped peaks in the spectrum. We develop an accurate model for the peak shape and show that the inclusion of the model in the gamma spectrum analysis makes it possible to quantify fast neutron scattering in the Ge crystal and improves the estimation of the baseline. This in turn facilitates the detection of fission products present at trace levels in environmental samples. The model, together with simulations, is used to deduce some properties of the underlying neutron energy distribution. The neutron evaporation temperature of 1.1 MeV is obtained from the analysis of environmental monitoring gamma spectra.