Hydrogen crossover through perfluorosulfonic acid membranes with variable side chains and its influence in fuel cell lifetime

In this study, hydrogen crossover in long side chain Nafion 211 membrane and short side chain Aquivion membrane is studied under different conditions. It is found that both temperature and relative humidity significantly influence the hydrogen crossover in the polymer electrode membranes (PEMs). The difference in hydrogen crossover behavior between Nafion 211 membrane and Aquivion membrane is revealed. The influence of hydrogen crossover on the fuel cell lifetime is also investigated under open circuit voltage (OCV). It is proved hydrogen crossover in the PEM would lead to possible degradation of the PEM and the decrease of electro-chemical surface area in the catalyst of the single cell. Single cell assembled with Aquivion membrane shows slower OCV and ECSA decay compared to the Nafion 211 single cell. Our results suggest that the PEM fuel cell lifetime is closely related to the hydrogen crossover in the PEM. The current study also highlights the possibility of improving the fuel cell durability by rational design of the PEM morphology.     

Evaluation of the pseudocapacitance in RuO2 with a RuO2/GC thin film electrode

The pseudocapacitance of nanocrystalline RuO₂ with BET surface area of 42 m² g⁻¹ was evaluated using a RuO₂ modified Glassy Carbon (RuO₂/GC) thin film electrode. The charge storage behavior of the RuO₂/GC thin film electrode was studied from fast to slow scan cyclic voltammetry between various potential windows. The utilization of the thin film electrode method for nanocrystalline RuO₂ with known specific surface area allowed a semi-quantitative understanding of the electric double-layer capacitance (C_dl), adsorption related charge (C_ad), and the irreversible redox related charge (C_irr) per unit mass and surface area of RuO₂. Comparison of the cyclic voltammograms between different voltage windows revealed that the contribution from C_irr is especially dominant below 0.4 V (versus RHE) at slow scan rates.     

不同电极电动修复铜镉复合污染土壤的研究

针对铜镉污染土壤问题,研究了不同电极材料对电动修复土壤效果的影响。采用不锈钢、石墨板、钛板、钛网四种不同电极对土壤进行修复。结果显示,石墨板电极对2种重金属的总去除率较好,Cu为40.34%,Cd为95.21%,且Cd的去除率明显高于Cu。另外,不同电极材料对修复过程中电流和处理后重金属形态分布的影响不大,其中石墨板电极电流稳定时的值为42mA,高于其他三种电极。     

三维电极法处理有机废水的研究进展

三维电极相较于二维电极具有传质效果好、电流效率高、体面比大等优点,其处理有机废水的研究和应用也越来越广泛。介绍了三维电极法的机理、粒子电极的分类及制备方法,同时对三维电极法与Fenton法、光催化氧化法、超声法、铁碳微电解法、生物法技术的联用进行了总结,并指出三维电极法目前存在的问题以及未来研究趋势。     

Electrochemical synthesis of hydrogen peroxide: Rotating disk electrode and fuel cell studies

The electrochemical reduction of oxygen on various catalysts was studied using the thin-layer rotating disk electrode (RDE) method. High-surface-area carbon was modified with an anthraquinone derivative and gold nanoparticles. Polytetrafluoroethylene (PTFE) and cationic polyelectrolyte (FAA) were used as binders in the preparation of thin-film electrodes. Our primary goal was to find a good electrocatalyst for the two-electron reduction of oxygen to hydrogen peroxide. All electrochemical measurements were carried out in 0.1 M KOH. Cyclic voltammetry was used in order to characterise the surface processes of the modified electrodes in O₂-free electrolyte. The RDE results revealed that the carbon-supported gold nanoparticles are active catalysts for the four-electron reduction of oxygen in alkaline solution. Anthraquinone-modified high-area carbon catalyses the two-electron reduction at low overpotentials, which is advantageous for hydrogen peroxide production.In addition, the polymer electrolyte fuel cell technology was used for the generation of hydrogen peroxide. The cell was equipped with a bipolar membrane which consisted of commercial Nafion 117 as a cation-exchange layer and FT-FAA as an anion-exchange layer. The bipolar membranes were prepared by a hot pressing method. Use of the FAA ionomer as a binder for the anthraquinone-modified carbon catalyst resulted in production of hydrogen peroxide.     

用于酶抑制分析的便携式电化学分析系统的研究

近年来,随着野外电化学分析需求的增加,便携式电化学分析仪得到很快发展,并在生物化学分析上得到一定应用.该文采用酶抑制分析原理,构建了一套便携式电化学检测系统.整个系统由恒电位仪采集数据,由ARM7系统板控制恒电位仪,结合丝网印刷工艺印刷电极.在嵌入式μClinux软件的控制下,实现酶传感器检测农药的功能.整个系统提供了良好的控制界面,实验结果显示对流磷检测限可低于2ppb.     

平衡双注照相乳化过程中PBr值测定 和微机调控的研究

报导在平衡双注照相乳化过程中用ＡｇＢｒ，ＡｇＣｌ单晶电极测定Ｐ＾Ｂｒ（Ｐ＾Ｃｌ，Ｐ＾Ａｇ和ｐＨ）值，用微机调控银盐（ＡｇＮＯ３）和卤盐（ＫＢｒ或ＫＣｌ）的流量，采用电极流动注入分析法ＥＦＩＡ（ＥｌｅｃｔｒｏｄｅＦｌｏｗＩｎｊｅｃｔｉｏｎＡｎａｌｙｓｉｓ）保持在照相乳化中所设定的Ｐ＾Ｂｒ（或Ｐ＾ｃｌ）值，从而得到了颗粒分布均匀和立方晶形的ＡｇＸ晶体，增加了照相乳化的感光度。     

硫酸溶液中Eu3+铅钙合金电极特性的影响

采用线性电势扫描伏安法、循环伏安法、计时电势法、交流阻抗法研究了不同Eu3+加入量的硫酸溶液中铅钙合金电极的电化学特性.实验结果表明:在硫酸溶液中添加Eu3+后,改善了Pb与PbSO4间转化反应的可逆性;Eu3+的存在提高了铅电极析氢电位;抑制了铅钙合金电极上氧化膜中高电阻的PbOn的生成,提高了氧化膜的导电性;阻碍了...     

大气压氩气等离子体射流长度的影响因素

为了研究不同大气压氩气射流结构的放电特性以及气流速率、外施电压和电极结构对射流体长度的影响,设计了外表面双电极、外表面单电极和中心同轴电极3种不同结构的氩气等离子体射流装置,并结合气体动力学和静电场进行了分析。实验结果表明,随着气流速率的增加,射流管内的氩气流动状态会经历从最初的层流态到中间的过渡态再到最后的湍流态的过...     

直流接地极线路招弧角间电弧的运动模型

针对直流接地极线路在遭受雷击和操作过电压时容易在绝缘子串间建立起电弧的问题,采用链式电弧模型,考虑电流元受磁场力、热浮力和空气阻力的作用以及电流元在不同运动速度下空气阻力系数与雷诺数之间的关系,分析电流元的受力,得出电弧的运动模型。通过仿真分析直流电弧在羊角型电极间的运动过程,发现直流电弧的熄弧时间与电流大小、电极张角之间存在相关关系,电弧电流和电极张角越大,直流电弧的熄弧时间越短。仿真研究结果为后续进行直流电弧试验提供理论依据。