质子交换膜燃料电池(PEMFC)的建模方法研究

质子交换膜燃料电池（PEMFC）是21世纪最有生命力的发电技术之一。参考大量文献，总结出PEMFC建模的基本方法。从电化学、液体动力学角度出发，全面地分析三维PEMFC数学模型，其具普遍意义。并阐明遗传算法、神经模糊控制技术在PEMFC控制方面的应用。     

Size effects on mass transport and storage in lithium batteries

The contribution deals with the significance of size effects for lithium-based batteries. The relevant size effects range from purely geometrical effects to effects in which the local thermodynamics is varied. In this context, several recent findings towards improved electrolytes and electrodes are discussed.     

Photoelectrochemical properties of anodic silver sulphide thin films

We have investigated the semi-conducting properties and photoelectrochemical characterization of Ag₂S thin films electrodeposited galvanostatically onto silver substrate from alkaline S²⁻ bath. Films grown with a low current density not exceeding 20 μA cm⁻² are uniform and well adhered. An optimal thickness of 1.34 μm has been determined. At high current density, oxygen evolution occurs simultaneously and provokes crashing of films. From photoelectrochemical measurements, the band gap was found to be 1.85 eV and the transition is indirectly allowed. The Mott-Schottky plot exhibits a linear behavior, characteristic of n-type conductivity, from which a flat band potential of − 1.20 V_SCE and a donor density of 5.63 × 10¹⁶ cm⁻³ were determined. The conduction band, located at 3.28 eV, is made up of mainly Ag-5s wave function. Ag₂S is long lived and under illumination, it is stabilized by holes consumption reactions involving S_n²⁻/S²⁻ redox couple. A conversion efficiency of 1.1% and a fill factor of 0.27 have been obtained. The electrochemical impedance spectroscopy, measured over a wide frequency range (10⁻²-10⁵ Hz), reveals contribution of the bulk effect. The experimental data are modeled by shifting the centre of the semi−circle down the real axis and interpreted in terms of constant phase element due mainly to the porosity and inhomogeneity of the film.     

Influence of electric current on bacterial viability in wastewater treatment

Minimizing the influence of electric current on bacterial viability in the electro-technologies such as electrophoresis and electrocoagulation is crucial in designing and operating the electric hybrid wastewater treatment system. In this study the biomass from a membrane bioreactor (MBR) was subjected to constant direct current and the bacterial viability was monitored against electrical intensity, duration as well as the spatial vicinity related to the electrodes. It was found that the bacterial viability was not significantly affected (less than 10% of death percentage) when the applied electric current density (CD) was less than 6.2 A/m² after 4 h. The percentage of live cell dropped by 15% and 29% at CD of 12.3 A/m² and 24.7 A/m², respectively. The pH of electrolytic biomass fluid has shifted to alkaline (from nearly neutral to around pH 10) at CD above 12.3 A/m², which could have been the contributing factor for the bacterial inactivation. The temperature change in the electrolytic media at all current densities during 4 h of experiment was less than 2 °C, thus temperature effects were negligible. Bacteria experienced different micro-environments in the electrochemical reactor. Bacterial cells on the cathode surface exhibited highest death rate, whereas bacteria outside the space between electrodes were the least affected. It was concluded that in an electro-technology integrated wastewater treatment process, sufficient mixing should be used to avoid localized inactivation of bacterial cells.     

Investigations on the monolayer structure of thiol SAMs and the influence of conjugated π-bonds on the electronic molecular conductivity

Thiols have been in the focus of recent research because of their capability to form self assembled monolayers (SAM) on noble and semi-noble metals opening a new field of fundamental research and its application in various branches, as e.g. in nano technology. In this paper, the investigation of SAMs of six specially tailored thiols with an aromatic head group on a preferentially (1 1 1) orientated Au-surface are described with special interest in their structure and the electronic conductivity in dependence on the number of conjugated π-bonds in the chain group. Potentiodynamic polarization curves in 0.5 M KOH with and without [Fe(CN)₆]^3−/4− were used to obtain information on the quality and conductivity of the SAMs while scanning tunneling microscopy (STM) and XPS were used for investigations on the monolayer structure. Additionally molecular dynamic calculations were performed to check the possibility and reliability of these calculations to predict the arrangement of the thiol molecules within the SAMs. The electron conductivity of these SAMs rises significantly with the amount of conjugated π-bonds. A naphthalene head group causes the formation of SAMs with a typical herringbone structure whereas anthraquinone leads to a mixture of parallel and herringbone arrangements.     

Electrochemical properties of double wall carbon nanotube electrodes

Electrochemical properties of double wall carbon nanotubes (DWNT) were assessed and compared to their single wall (SWNT) counterparts. The double and single wall carbon nanotube materials were characterized by Raman spectroscopy, scanning and transmission electron microscopy and electrochemistry. The electrochemical behavior of DWNT film electrodes was characterized by using cyclic voltammetry of ferricyanide and NADH. It is shown that while both DWNT and SWNT were significantly functionalized with oxygen containing groups, double wall carbon nanotube film electrodes show a fast electron transfer and substantial decrease of overpotential of NADH when compared to the same way treated single wall carbon nanotubes. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

船用继动器壳体材料的腐蚀性能分析

用电化学测试手段分别测定了 2 0钢、2Cr1 3、QAl9 2、QAl 1 0 3 1 .5和QAl1 0 4 4等 5种材料在NaCl溶液中的腐蚀电位及与QAl9 2偶接时的电偶腐蚀电流的变化 ,并对测试后各试样的腐蚀状态进行了观察。结果表明 ,铝青铜材料的抗腐蚀性比钢好。其中QAl 1 0 4 4的腐蚀电位最为偏正 ,但它与QAl9 2配副会对QAl 9 2产生较大的阳极电偶腐蚀 ;QAl9 2和QAl 1 0 3 1 .5材料与QAl 9 2配副均有较好的耐电偶腐蚀性能。研究结果对继动器壳体材料的选择具有指导意义     

Tantalum powder production by magnesiothermic reduction of TaCl5 through an electronically mediated reaction (EMR)

Tantalum powder production by magnesiothermic reduction of tantalum pentachloride (TaCl₅) through an electronically mediated reaction (EMR) has been examined. Feed material, TaCl₅, and reductant magnesium alloy were charged into electronically isolated locations in the molten salt (e.g. NaCl–KCl–MgCl₂) at 1073 K. After providing external path for electron flow, the current flow between the feed and the reductant locations was monitored. A large current, more than 1 A, was detected during the reaction and tantalum powder with low nickel and silver content was obtained, although liquid Mg–Ag–Ni alloy was used as the reductant. This clearly demonstrates that tantalum powder can be produced by electronically mediated reaction (EMR) without direct physical contact between the feed (TaCl₅) and the reductant (magnesium). The feasibility of tantalum reduction using Dy²⁺ ions dissolved in molten salt has also been demonstrated by utilizing molten salt containing DyCl₂ as a reaction mediator. The mechanism of magnesiothermic reduction of TaCl₅ in the molten salt is discussed using isothermal chemical potential diagrams.     

纳米碳管储氢机理的电化学研究

对流动催化剂法制备的平均直径为6nm的多壁纲米碳管（Multi-walled carbon nanotubes,MWNTs)进行纯化处理，提纯后的多壁纳米碳管利用透射电镜（TEM）表征和电化学储氢研究。同时对该纳米碳管电极进行了自放电实验。结果表明：多壁纳米碳管具有奶高的电化学储氢容量（739mAh/g），但氢与多壁纳米碳管之间的作用力很微弱，氢很容易从多壁纳米碳管中逃逸出。另外，通过对多壁纳米碳管的气相储氢性能的测试，根据实验结果推测；纳米碳管电化学储氢和气相储氢的主要吸附机理相同，即都是物理吸附。