直接甲醇燃料电池的交流阻抗谱分析*

由于能够提供比直流测试方法更为丰富的信息,交流阻抗图谱近些年被广泛的用于直接甲醇燃料电池的研究中。同PEMFC相比,直接甲醇燃料电池具有更为复杂的电极体系。本文通过对交流阻抗技术在直接甲醇燃料电池领域应用的几个关键技术问题的分析,并按照阻抗分析过程的具体的实施步骤加以组织,结合具体的应用实例以阐述交流阻抗谱在直接甲醇燃料电池的各个应用方面,包括电池的原位极化分析,反应机理的剖析,材料性能评估等。     

Pt/纳米碳管空气电极氧还原反应的电催化性能

以不同质量比的铂、纳米碳管、活性炭为催化层制备空气电极并测定其稳态极化曲线和交流阻抗.研究发现,纳米碳管经硝酸处理后其氧还原反应性能得到提高,特别是将表面氧化后再沉积Pt,对氧的电还原反应影响更显著.以质量比4∶1的活性炭/纳米碳管载Pt制备的空气电极,在过电位ηc为500～600mV下,氧还原电流可达600～700mA·cm-2.EIS测试表明,纳米碳管载Pt后的欧姆极化阻抗和电化学阻抗均非常小.     

固体氧化物燃料电池电化学阻抗谱差异化研究方法和分解

电化学阻抗谱技术(EIS)在固体氧化物燃料电池(SOFC)中已获得广泛应用。在EIS分析过程中,研究者能够清楚地获得燃料电池内部因纯离子(电子)导电引起的欧姆电阻和因电化学过程、扩散作用引起的极化阻抗的大小,但是对于极化阻抗的构成缺乏进一步解析。本文选用传统的Ni-YSZ阳极支撑电池,通过改变测试温度、阳极运行气氛和阴极运行气氛,设计了一套完整的阻抗差异分析(ADIS)实验。并基于弛豫时间分布法(DRT)和阻抗差异分析法,系统地分析并解释了阻抗谱中各频率段对应阻抗的物理或(电)化学含义,将该类型电池阻抗谱以6个RQ并联电路予以拟合,为之后燃料电池性能稳定性的研究奠定基础。     

基于丝网印刷电极的阻抗型免疫传感器用于检测烯效唑

采用循环伏安法在丝网印刷碳电极表面电聚合聚苯胺/壳聚糖复合膜,利用静电吸附作用固定烯效唑抗体,制备了检测烯效唑的阻抗型免疫传感器.采用循环伏安法和电化学阻抗谱对电极修饰过程进行了表征,并考察了缓冲溶液pH值、温育温度及时间对免疫反应的影响.在优化的条件下研究了免疫传感器的性能.此免疫传感器具有灵敏度高、特异性强、重现性和稳定性好的特点,对烯效唑的线性检测范围为0.01 ～100 mg/L,相关系数为0.999,检出限为8μg/L(3σ).白菜样品中添加0.05,0.10和1.0 mg/kg烯效唑,平均回收率为98.5％ ～ 104.6％,相对标准偏差为3.3％ ～4.3％,检测结果与气相色谱法的检测结果相符.     

电化学阻抗谱法测定固态聚合物电解质的本体电阻

采用电化学阻抗谱法,对阻抗谱中的聚合物电解质本体电阻（Rb）与膜厚（L）的关系和固体聚合物电解质/惰性电极间的界面阻抗随直流电压的变化趋势进行了研究.结果表明,阻抗谱中聚合物电解质本体电阻（Rb）含有一定的阻塞电极/聚合物电解质间的界面阻抗;由于界面双电层电容的变化,在直流电压0.15～3 V范围内,界面阻抗随电压的增大而减小.     

微囊藻毒素-LR阻抗型电化学免疫传感器的研究

基于1,6-己二硫醇自组装技术和纳米金吸附作用相结合的方法固定微囊藻毒素抗体,采用循环伏安法及交流阻抗法研究了该修饰电极的电化学性质,并优化了微囊藻毒素-LR(MC-LR)的测定条件.结果表明,在优化条件下,阻抗变化值与MC-LR标准品质量浓度分别在0.25 ～2.0 μg/L和2.0 ～95 μg/L 范围内呈良好的线性关系,其线性相关系数分别为0.994 4和0.997 2,检出限达0.085 μg/L(S/N=3);电极的重现性及稳定性较好,连续测定12次,相对标准偏差为7.8%;4 ℃下储存60 d后阻抗响应信号无明显变化;应用于饮用水中MC-LR的测定,样品的回收率为93% ～118%;检测时间为15 min.该传感器无需标记、灵敏度高、稳定性好,可用于快速检测饮用水源水中的MC-LR.     

抗人乳腺癌糖蛋白单克隆抗体及相应抗原免疫反应的电化学阻抗 免疫分析研究

报道了一种用于抗人乳腺癌糖蛋白单克隆抗体(GP1D8)及相应抗原免疫反应的电化学阻抗免疫分析法。本方法采用将抗体直接定向组装到石英晶片/金电极上,实验中设计的阻抗传感测量只响应免疫信号。结果显示,当组装单克隆抗体的金电极被插入特殊抗原的溶液中时,电化学阻抗谱(EIS)发生明显的变化,成功地检测了组装抗体和相应抗原的免疫反应。     

抗人乳腺癌糖蛋白单克隆抗体及相应抗原免疫反应的电化学阻抗免疫分析研究

报道了一种用于抗人乳腺癌糖蛋白单克隆抗体(GP1D8)及相应抗原免疫反应的电化学阻抗免疫分析法。本方法采用将抗体直接定向组装到石英晶片/金电极上,实验中设计的阻抗传感测量只响应免疫信号。结果显示,当组装单克隆抗体的金电极被插入特殊抗原的溶液中时,电化学阻抗谱(EIS)发生明显的变化,成功地检测了组装抗体和相应抗原的免疫反应。     

检测禽流感H5亚型病毒的阻抗型免疫研究

研制了一种可用于H5亚型禽流感病毒快速检测的阻抗型免疫传感器。通过蛋白A将H5N1表面抗原血凝素(HA)的单克隆抗体固定于金叉指阵列微电极表面,并与待测溶液中的目标抗原H5N1进行免疫反应。在[Fe(CN)6]3"/4"溶液中进行电化学阻抗谱扫描,表征电极的表面修饰及抗原捕获过程。当H5N1病毒浓度在21～26 HA unit/50μL范围时,其浓度的对数值与叉指阵列微电极的电子传递阻抗的变化值呈线性关系,相关系数为0.9885;检出限为20 HA unit/50μL,检测时间为1 h。此传感器特异性好,灵敏度高,可以重复使用,在病原微生物快速检测领域具有良好的应用前景。     

基于伪随机二进制序列的阻抗谱快速重构及其在电化学能源领域的应用

阻抗谱的应用范围越来越广,其传统测试方法耗时长的问题也日益突出. 提高阻抗谱测量速度的各种尝试中,合成宽带激励信号和设计高效率估计算法被认为是最具潜力的解决方案,由于伪随机二进制序列（pseudo-random binary sequence,PRBS）具有功率谱平坦和易生成等优点,它在阻抗谱快速测试中具有独特优势. 本文综述了快速阻抗谱测试中三个核心问题：PRBS信号类型、不同快速算法及其在电化学能源领域的典型应用. 对于PRBS信号类型,即最大长度序列信号、混合PRBS、离散区间二进制序列和正交PRBS,本文讨论了它们各自的特点和应用范围;对于不同的PRBS激励信号的快速算法,即离散傅里叶变换/快速傅里叶变换、小波变换、快速m序列变换、基于系统辨识的参数估计算法以及这些算法各自的特点和应用范围,本文进行了深入的分析;对于PRBS阻抗谱快速测量的应用,本文以铅酸电池、锂离子电池、质子交换膜燃料电池和超级电容器等电化学能源为例,验证了其应用的可行性. 为促进技术的进一步完善,本文总结和分析了PRBS阻抗谱快速测量存在的挑战,并提出了克服这些挑战所必需的未来研究方略.     

Electrochemical corrosion kinetics of tin and tin amalgams in NaCl aqueous solutions

Electrochemical techniques were used to determine the corrosion rate of pure tin metal as compared to 80 Sn/20 Hg tin amalgam. X-ray diagrams showed that this amalgam was a crystalline γ₂ phase, whereas a 50 Sn/50 Hg amalgam contained liquid alloy embedded in the same γ₂ phase. Open circuit potential measurements, combined with narrow range potential scanning voltammetry, lead to the conclusion that amalgamation resulted in enhancement of the corrosion current, mainly by increasing the cathodic electron transfer reaction kinetics both in deaerated and in oxygen-saturated NaCl solution. When maintained at zero current potential in a solution containing dissolved O₂ gas, the samples were gradually covered with an insulating oxide layer which was identified by a series of electrochemical impedance diagrams recorded at different time intervals. The oxide layer was firmly adherent to the bulk tin metal but was poor at protecting the amalgam electrode. Finally, at potential values where the anodic current reached a few mA/cm², the pure tin metal surface was suddenly deteriorated by the formation of extremely deep pinhole corrosion pits, while this effect was smoothed down by amalgamation. Electronic Publication     

Synthesis and characterization of novel 4-nitro-2-(octyloxy)phenoxy substituted symmetrical and unsymmetrical Zn(II), Co(II) and Lu(III) phthalocyanines

Compounds 3 and 4 have been prepared by the reaction of 4-nitrocatechol 1 and 4-nitrophthalonitrile 2 by a common method, aromatic nucleophilic subtitution of the nitro group in 4-nitrophthalonitrile. Starting from 4 and 1-bromooctane, their alkylation reaction gave compound 5. Zn(II) 8, Co(II) 9 and Lu(III) 10 complexes were synthesized from the corresponding metal salts by the tetramerization of compound 5. Compound 7 was prepared by the statistical condensation of 5 and 4,5-bis(hexylthio)phthalonitrile 6 with CoCl₂ · 6H₂O in dry dimethylformamide. The new compounds were characterized by FT-IR, UV/Vis, NMR and mass spectra. The electrochemical properties of the complexes were also investigated by cyclic voltammetry in non-aqueous medium. The effect of temperature on the dc conductivity and the impedance spectra of spin coated film of the compounds was investigated at temperatures between 295 and 433 K and in the frequency range 40–10⁵ Hz. Thermally activated conductivity dependence on temperature was observed for all compounds.     

基于介电泳诱捕与阻抗测量的三维网格型生物传感器的研究

微粒分离与检测的集成,一直是微全分析系统亟待解决的难题.结合介电泳与生物阻抗谱测量,设计了一种三维介电泳芯片.以SU8胶为材料的绝缘夹层以及其上方和下方网格状交叉的电极阵列,构成了芯片的关键区域,且在SU8绝缘夹层中利用光刻技术形成了圆柱状小势阱.三维的网格状阵列结构及具有束缚电场功能的SU8电介质,共同形成了其独特的...     

Double template electrochemical deposition and characterization of NiCo and NiCu alloys nanoparticles and nanofilms

The principle of double template deposition technique was developed to prepare NiCo and NiCu alloy nanomaterials. Ordered particles of about 800 nm high were obtained by reduction of ions from aqueous solution into the pores of anodic aluminum oxide (AAO) membrane with intact barrier layer. The size of the nanoparticles was significantly reduced by combination of AAO and the hexagonal phase of a lyotropic liquid crystal. The scanning tunneling microscopy (STM) micrograph of the material prepared in the presence of liquid crystal reveals the hexagonal array of cylindrical pores. The corrosion potential of the alloy nanofilm shifted to more negative values when the sizes of the particles decrease. The anodic linear sweep voltammetry shows, in each case, various current peaks characteristic of the dissolution of chemical elements in the film.     

Electrochemical and surface characterization of mild steel with corrosion resistant zirconia network fabricated by aqueous sol-gel technique

Zirconia (ZrO₂) coating was developed on mild steel surface through an aqueous sol-gel route followed by heat treatment. The coating quality was optimized by varying dipping time, curing time, and drying temperature. ZrO₂ coating was competent to prevent a substantial corrosion loss in 0.5 ​M–2 ​M hydrochloric acid with more than 90% efficiency. The morphology of coated surface has revealed the formation of a fine ZrO₂ network on the metal surface at optimum conditions. This network is found to be effective to control steel deterioration in hydrochloric acid and the same appeared to be either cracked or irregular for less efficient formulations.     

Dielectric,impedance and excitation performance of Aurivillius oxides: Bi4Pb2Zr2TiFeNbO18

The Aurivillius phase-based composition bearing chemical formula Bi₄Pb₂Zr₂TiFeNbO₁₈ (termed as BPZTFNO) was synthesized by a solid-state method. The structural analysis as obtained from the X-ray pattern has depicted an orthorhombic phase. The various size and morphology of grains are distributed throughout the natural surface as revealed from microstructure analysis. The dielectric and electrical study of the BPZTFNO is taken at a various sweep of frequency (1 kHz–1 MHz) and temperatures (25–400 °C). The ferroelectric-paraelectric phase transition is well illustrated from the temperature-dependent dielectric constant. The complex impedance analysis suggests the association of grain effect. The relaxation of non-Debye nature is shown in the impedance study. The formed sample is subjected to an electric field and further its excitation performance is examined suggesting its possible usage in devices.     

Impedance spectroscopy investigation of the water-in-oil microemulsions formation

In this work it was investigated the microemulsion formation using impedance spectroscopy analysis. The results indicated that the microemulsion formation is clearly observed on the impedance complex plane. The phase transition related with microemulsion formation is characterized by a time relaxation distribution. In the condition of the microemulsion formation, the impedance spectra are characterized by a single relaxation time.     

Electrochemical Identification and Categorization of the Protective Quality of Intact and Damaged Coatings

Defective polymeric coatings that are particularly relevant in the conservation of outdoor metalwork, are analyzed using electrochemical impedance spectroscopy (EIS), validated by Kramers? Kronig transformations, and modeled using electrical equivalent circuit models (EECs). Using twenty different coated panels of five different coating types, ten mathematical methods for categorizing the protective qualities of coatings are explored as simpler and faster alternatives to circuit modeling; three methods gave a perfect correlation with the category determined by circuit modeling. Our findings highlight the need for fitting data to EECs before relying upon purely mathematical parameters for evaluating protective coating quality.     

Defect and transport properties of nanocrystalline ceramics and thin films

This paper presents an overview of recent research on the defect and transport properties of nanocrystalline ionic and mixed conducting ceramics and thin films. In the first part, some basic concepts and properties of boundaries are reviewed, including diffusion, segregation, and space charge regions. Experimental data on nanoceramics and thin films made from pure and doped CeO₂, TiO₂, ZrO₂, and CaF₂ are presented and discussed in the second part; opportunities for future work on this topic are outlined. Electronic Publication