The design of polyaniline based sensor for the qualitative estimation of malonaldehyde

The detection of contaminated food in every stage of processing required new technology for fast identification and isolation of toxicity in food. Since effect of food contaminant are severe to human health, the need of pioneer technologies also increasing over last few decades. In the current study, MDA was prepared by hydrolysis of 1,1,3,3-tetramethoxypropane in HCl media and used in the electrochemical studies. The electrochemical sensor was fabricated with modified glassy carbon electrode with polyaniline. These sensors were used for detection of sodium salt of malonaldehyde and observed that a high sensitivity in the concentration range similar to 1 x 10(-1) M and 1 x 10(-2) M. Tafel plots show the variation of over potential from -1.73 V to -3.74 V up to 10(-5) mol/L indicating the lower limit of detection of the system. (C) 2013 Elsevier Ltd. All rights reserved.

Effect of TiN particulate reinforcement on corrosive behaviour of aluminium 6061 composites in chloride medium

In the present investigation, the corrosive behaviour of Al 6061-TiN particulate composites prepared by liquid metallurgy has been studied in chloride medium using electroanalytical techniques such as Tafel, cyclic polarization and electrochemical impedance spectroscopy (EIS). Surface morphology of the sample electrodes was examined using scanning electron micrography and energy dispersive X-ray methods. X-ray diffraction technique was used to confirm inclusion of TiN particulates in the matrix alloy and identify the alloying elements and intermetallic compounds in the Al 6061 composites. Polarization studies indicate an increase in the corrosion resistance in composites compared to the matrix alloy. EIS study reveals that the polarization resistance (R (p)) increases with increase in TiN content in composites, thus confirming improved corrosion resistance in composites. The observed decrease in corrosion rate in the case of composites is due to decoupling between TiN particles and Al 6061 alloy. It is understood that after the initiation of corrosion, interfacial corrosion products may have decoupled the conducting ceramic TiN from Al 6061 matrix alloy thus eliminating the galvanic effect between them.

Equiatomic ternary chalcogenide: PdPS and its reduced graphene oxide composite for efficient electrocatalytic hydrogen evolution

The layered ternary chalcogenide, palladium phosphorous sulphide (PdPS), and its composite with reduced graphene oxide are shown to be efficient hydrogen evolution electrocatalysts. The Tafel slope and the exchange current density values associated with hydrogen evolution reaction are determined to be 46 mV dec(-1) and 1.4 x 10(-4) A cm(-2) respectively.

Electrochemical behavior of Zn-graphene composite coatings

A Zn-graphene composite coating was electrodeposited on mild steel. The graphene was synthesized by electrochemical exfoliation of graphite. Electron microscopy, energy-dispersive X-ray spectroscopy and X-ray diffraction techniques were used to characterize the coatings. Compared to a pure Zn coating, the Zn-graphene coating exhibited reduced grain size, reduced surface defects, hillock structures over the coating surface and an altered texture. The corrosion behavior of the coatings was examined by Tafel polarization and electrochemical impedance spectroscopic methods. A significant improvement in the corrosion resistance in terms of reduction in corrosion current and corrosion rate and increase in polarization resistance was noted in the case of the Zn coating containing graphene.

In Situ Crystallographic Probing on Ameliorating Effect of Sulfide Additives and Carbon Grafting in Iron Electrodes

Beneficial effects of carbon grafting into the iron active material for rechargeable alkaline-iron-electrodes with and without Bi2S3 additive is probed by in situ X-ray diffraction in conjunction with Extended X-ray Absorption Fine Structure (EXAFS) and electrochemistry. EXAFS data unravel that the composition of pristine active material (PAM) for iron electrodes comprises 87% of magnetite and 13% of alpha-iron while carbon-grafted active material comprises 60% of magnetite and 40% of alpha-iron. In situ XRD patterns are recorded using a specially designed electrochemical cell. XRD data reflect that magnetite present in PAM iron electrode, without bismuth sulfide additive, is not reduced during charging while PAM iron electrode with bismuth sulfide additive is partially reduced to alpha-Fe/Fe(OH)(2). Interestingly, carbon-grafted-iron electrodes with bismuth sulfide exhibit complete conversion of active material to alpha-Fe/Fe(OH)2. The ameliorating effect of carbon grafting is substantiated by kinetic parameters obtained from steady-state potentiostatic polarization and Tafel plots. The mechanism for iron-electrode charge - discharge reactions are discussed in the light of the potential - pH diagrams for Fe - H2O, S - H2O and FeSads - H2O systems and it is surmised that carbon grafting into iron active material promotes its electrochemical utilization. (C) The Author(s) 2015. Published by ECS. All rights reserved.

Electrically conducting palladium selenide (Pd4Se, Pd17Se15, Pd7Se4) phases: synthesis and activity towards hydrogen evolution reaction

Electrically conducting, continuous films of different phases of palladium selenides are synthesized by the thermolysis of single source molecular precursors. The films are found to be adherent on flat substrates such as glass, indium tin oxide and glassy carbon and are stable under electrochemical conditions. They are electrocatalytically active and in particular, for hydrogen evolution reaction. Catalytic activities with low Tafel slopes of 50-60 mV per decade are observed.

Electrochemical deposition of manganese oxide-phosphate-reduced graphene oxide composite and electrocatalysis of the oxygen evolution reaction

A composite of manganese oxide and reduced graphene oxide (rGO) is prepared in a single step electrochemical reduction process in a phosphate buffer solution for studying as an electrocatalyst for the oxygen evolution reaction (OER). The novel composite catalyst, namely, MnOx-Pi-rGO, is electrodeposited from a suspension of graphene oxide (GO) in a neutral phosphate buffer solution containing KMnO4. The manganese oxide incorporates phosphate ions and deposits on the rGO sheet, which in turn is formed on the substrate electrode by electrochemical reduction of GO in the suspension. The OER is studied with the MnOx-Pi-rGO catalyst in a neutral phosphate electrolyte by linear sweep voltammetry. The results indicate a positive influence of rGO in the catalyst. By varying the ratio of KMnO4 and GO in the deposition medium and performing linear sweep voltammetry for the OER, the optimum composition of the deposition medium is obtained as 20 mM KMnO4 + 6.5% GO in 0.1 M phosphate buffer solution of pH 7. Under identical conditions, the MnOx-Pi-rGO catalyst exhibits 6.2 mA cm(-2) OER current against 2.9 mA cm(-2) by MnOx-Pi catalyst at 2.05 V in neutral phosphate solution. The Tafel slopes measured for OER at MnOx-Pi and MnOx-Pi-rGO are similar in magnitude at about 0.180 V decade(-1). The high Tafel slopes are attributed to partial dissolution of the catalyst during oxygen evolution. The O-2 evolved at the catalyst is measured by the water displacement method and the positive role of rGO on catalytic activity of MnOx-Pi is demonstrated.

导电高分子在防腐领域的应用及其相关机理研究

本论文研究了聚苯胺与常用涂料的共混行为，针对本征态和掺杂态聚苯胺各自的特点，开发出本征态聚苯胺/环氧树脂和掺杂态聚苯胺/聚氨酯两种共混防腐体系：利用线性极化和Tafel曲线等电化学方法对两个体系的防腐性能进行了监测：采用EIS和XPS等技术对聚苯胺防腐机理进行了探讨。以有机胺为桥梁率先开发出无溶剂本征态聚苯胺/环氧树脂共混防腐体系，用SEM研究发现该体系中聚苯胺分散的非常好，达到纳米级分散，并且同环氧树脂形成相互交叉的网状结构。有机胺对聚苯胺既有一定的溶解作用又有一定的降解作用。用IR和UV-Vis研究发现聚苯胺在有机胺中的降解产物基本上保持了聚苯胺的性质，但是其分子量变小了，部分可以溶于乙醇中，而且该苯胺低聚物对于酸碱的敏感程度大大降低，只有浓酸才能将其掺杂。有机酸掺杂的聚苯胺可以很好地分散在聚氨酯中形成掺杂态聚苯胺/聚氨酯共混防腐体系。用SEM观察发现掺杂态聚苯胺在聚氨酯中形成了很好的网状结构。同时对于影响掺杂态聚苯胺在聚氨酯中分散的各种因素(掺杂比例、温度，溶剂量等)进行了分析。指出聚氨酯乙组份中的多元醇对已经分散在聚氨酯中的掺杂态聚苯胺有稳定作用。利用线性极化和Tafel曲线对本征态聚苯胺/环氧树脂和掺杂态聚苯胺/聚氨酯共混体系的防腐性能进行了监测，发现聚苯胺的加入使得常用涂料的自然腐蚀电位E_(corr)正向移动；相应的自然腐蚀电流i_(corr)明显降低；共混膜的极化电阻R_p比空白样品的极化电阻显著增大。利用EIS技术对本征态聚苯胺/环氧树脂和掺杂态聚苯胺/聚氨酯共混体系进行了阻抗分析，并结合XPS结果提出聚苯胺防腐涂料具有良好防腐效果的关键是聚苯胺和铁相互作用，在两者界面处形成了一层致密的氧化膜。该层氧化膜的存在可以大大提高防腐涂层的孔阻R_(pore)和最大值阻抗Z_(max)，从而使得聚苯胺防腐涂层具有很好的阻挡腐蚀介质渗透的作用。同时利用断点频率f_b分析了个涂层附着力的变化趋势以及剥离面积A_d的大小。在文献总结和实验积累的基础上分别提出了本征态聚苯胺/环氧树脂和掺杂态聚苯胺/聚氨酯共混体系的等效电路，并利用非线性最小二乘法(NLCN)对所得Nyquist和Bode谱进行了模拟，给出了比较好的拟合曲线。从各等效元件的拟合值可以直接比较各膜的R_(pore)的大小，并且可以看出界面氧化膜电阻R_(ol)对于聚苯胺膜阻抗值的贡献。

PH值、氯离子浓度和监酸浓度对于铁的腐蚀电化学行为的影响

本文研究了Armco铁在盐酸溶液中的腐蚀电化学行为，探讨了ψ~-离子和PH值对铁的阳极溶解过程的影响，并进而讨论了ψ~-离子浓度和PH值对铁的腐蚀电化学行为的影响之间是否存在交互效应。在本工作中，作者提出了两个新的研究方法：(a) 从单支弱极化曲线测定腐蚀电流和阴、阳极反应的Tafep斜率；(b)根据交流方波电流扰动的响应函数方程测定极化电阻Rp和界面电容C。设I_c、I_(2c)、I_(3c)及I_(4c)分别为对应于弱极化区内极化电位为ΔE、2ΔE、3ΔE和4ΔE的极化电流，且令a = I_(2c)/I_c, b = I_(3c)/I_c, c = I_(4c)/I_(2c), 而(4b-3a~2)~(1/2)、(3c-2b)~(1/2)、(2c-a~2)~(1/2)则以S_j表示之，则可得到：I_(corr) = I_c/S_j b_c = ΔE/lg((a+s_j)/2) b_a = -ΔE/lg((a-s_j)/2)为了方便，准确地求出动力学参数，可选用一系列的ΔE值，得出相应的极化电流I_λ，求出S_λ，应用统计方法处理数据，可得：I_(corr) = ∑ from i=1 to n I_λ/∑ from i=1 ton S_λ b_c = ∑ form λ to n ΔE_λ/∑ form i=1 to n lg ((a_λ+S_λ)/2) b_a = ∑ form i=1 ton ΔE_λ/∑ form i=1 to n lg ((a_λ-S_λ)/2)在线性极化区间内向腐蚀金属电极体系施加一交流方波电流扰动讯号时，通过Laplace变换分析，得到相应的响应函数方程为：E_1(t) = λ_o(R_s+R_p) - 2λ_oR_p (e~(-(τ-λ)/RpC))/(1+e~(λ/RpC)) (o<τ<λ) E_2(t) = -λ_o(R_s+R_p) + 2λ_oR_p (e~(-(τ-λ)/RpC))/(1+e~(λ/RpC)) (λ<τ<2λ)由此方程可知，它们在E～λ坐标系统中的轨迹为对称兴致勃勃原点的两条直线。由此方程可进一步得到:ΔE = 2λ_oR_p (e~(λ/RpC)-1)/(e~(λ/RpC)+1) = 2λ_oR_p t_(anh)(λ/(2RpC)) Δh = 2λ_o Rs式中ΔE为单支响应直线的长度，Δh则为两条直线最高点之间的距离。上述公式可进一步简化为：Rp =(ΔE)/(2λ_o) λ>>RpC (λ_o)/(ΔE) = C/λ + 1/(2Rp) λ<Tafel线段的数据分析而得到的离子反应级数和Tafel斜率值与弱极化区得到的结果是一致的。由此，讨论了铁的阳极溶解过程，提出了反应机理，由此机理推论而得出的有关的电化学参数的理论值与实验值符合得很好。最后，对PH值和ψ~-离子浓度对铁的腐蚀电化学行为的影响之间是否存在交互效应进行了探讨。由实验数据的分析得到，PH值和ψ~-离子浓度的效应之间不存在交互效应，或者交互效应不大。

Cr(III)盐在Pt电极和PbO_2电极上阳极氧化为络酸盐的机理的研究

关于Cr(III)阳极氧化为Cr(VI)的过程，在工业应用方面已有许多工作，但对机理尚不清楚。本文对Pt电极和PbO_2电极上的这一过程进行了动力学的研究，首次得到了Cr(VI)在这两种电极上阳极形成的真实动力学数据，并提出了与实验基本相符的反应机理。用“分解极化曲线法”和稳态极化曲线的测量，得到了[H_2SO_4]和[SO_4~=]恒定的不同浓度Cr_2(SO_4)_3溶液中Cr(VI)在光滑Pt电极上阳极形成的真实动力学数据，可用如下方程式来表达：在较低电位下φ = a + 0.25 log i_2 - 0.23 log [Cr(III)]在较高电位下φ = a' + 0.48 log i_2 - 0.44 log [Cr(III)]同时得到了氧的阳极发生的动力学数据，Tafel线性区的斜率接近于2.303 RT/ΔF (Δ ≈ 0.5)。动力学方程式的推导与实验的比较表明，在光滑Pt电极上Cr(VI)是由Cr(II)通过“活性氧”的氧化形成的，提出了如下反应机理：H_2O → (OH)_(ad) + H~+ + e~- 2(OH)_(ad) → (O)_(ad) + H_2O 2(O)_(ad) →O_2 (OH)_(ad) + [Cr(H_2O)_6]~(3+) → (CrO_2)_(ad) + 3H~+ + 5H_2O (CrO_2)_(ad) + H_2O → (CrO_3~-)_(ad) + 2H~+ + e~- (CrO_3~-)_(ad) + H_2O → HCrO_4~- + H~+ + e~- 2HCrO_4~- <-> Cr_2O_7~(2-) + H_2O 在[H_2SO_4]和[SO_4~(2-)]恒定的不同浓度Cr_2(SO_4)_3溶液中，测得了Cr(VI)在Δ-PbO_2电极上阳极形成的动力学数据：在较低电位下φ = a + 0.28 log i_2 - 0.30 log [Cr(III)]在较高电位下φ = a' + 0.55 log i_2 - 0.51 log [Cr(III)]氧的极化曲线的Tafel线性区斜率也为2.303RT/ΔF (Δ approx= 0.5)。PbO_2电极和Pt电极上分解极化曲线的比较表明，Cr(VI)在前一电极上阳极形成的过电位远低于在后一电极上，这可能是两电极上电流效率显著差别的原因。测得了PbO_2电极上不同过电位下电极反应的有效活化能，其数值均在10 Kcal mol~(-1)以上，且随着极化的增大而减小，据此在动力学处理中可以忽略扩散的作用，交流阻抗的研究进一步证实了这一点。溶液pH的增大或[H_2SO_4]的减小会降低Cr(VI)阳极形成的过电位，使反应加速。在[H_2SO_4]和[SO_4~(2-)]恒定的不同浓度Cr_2(SO_4)_3溶液中，测得了在不同电位极化下PbO_2电极的阻抗频谱。在较高电位下阻抗谱呈现明显的两个半圆，表明电极过程包括了中间吸附物的形成。求得的吸附电容Cad比双层电容Cd大1-2个数量级；Cd比通常光滑电极表面的Cd大得多，这可能与SO_4~(2-)，HCrO_4~-, Cr_2O_7~-以及[_((SO_4))~((H_2O)_2) Cr_((SO_4))~((OH)_2) Cr_((SO_4))~((OH_2)_2)]~(2-)等阳离子的特性吸附有关。从动力学的推导与实验的比较得出，在PbO_2电极上Cr(VI)也按“活性氧”机构形成，可能的机理如下：H_2O → (OH)_(ad) + H~+ + e~- (OH)_(ad) + H_2O → (O)_(ad) + H_3O~+ + e~- 2(O)_(ad) → O_2 [Cr(H_2O)_6]~(3+) + (O)_(ad) → (CrO_3~-)_(ad) + 4H~+ + 4H_2O (CrO_3~-)_(ad) + H_2O → HCrO_4~- + H~+ +e~- 2HCrO_4~- <-> Cr_2O_7~(2-) + H_2O.

金属原卟啉的电化学聚合以及氧在其上的电催化还原

氧的电还原不仅在高效能量转换和储存装置中，而且在电解工业中降低电耗方面也起着重要的作用。为此寻求催化活性好、稳定性高和经济适用的氧还原催化剂是一个十分重要的课题。许多研究工作者已发现卟啉、酞菁一类过渡金属大环络合物对氧的催化还原有很高活性，但是其稳定性差。为提高催化剂的稳定性，人们进行了多种尝试，如真空沉积、热处理、将活性单体嵌入Nafion膜或导电高聚物膜中等，但都未能很好解决稳定性问题。我们试图将活性单体用电化学方法直接聚合在电极基底上，以提高催化剂的稳定性。为此，本论文主要进行了以下工作：（1）活性单体的合成，（2）钴原卟啉二甲酯(CoPP)的电化学聚合，以及（3）氧在聚CoPP膜上电还原的活性、稳定性和机理等的研究。一、通过实验摸索出一条由血红素单体合成CoPP单体的简便途径。二、研究了高聚物膜的电化学聚合和表征，以及膜在水溶液中的电化学行为。用循环伏安法(C.V.)和恒电位(P. S.)方法研究了CoPP单体直接聚合在不同的电极基底[如玻璃碳(GC)、烧结石墨(Pc)、导电玻璃和Pt等]上的条件。发现C.V.图上有三对氧化还原峰。在聚合的过程中，中断所旋加的电位时，聚合电量继续增加。找到了若干种能溶能聚CoPP膜的有机溶剂和水溶液，并对高聚物膜进行了红外、紫外表征，发现聚CoPP膜的紫外吸收红移不大，CoPP单体在聚合中，卟啉环上的一个乙烯基被饱和，卟啉环没有被破坏，在聚CoPP膜中，每个卟啉环中仍存在由四氦围绕着的中心金属。扫描电镜结果表明：高电位下聚合膜的空隙，比低电位下聚合膜的多，由此提出了阳离子自由基的聚合机理。此外我们还发现在酸性溶液中，能观察到明显的中心金属离子的氧化还原峰。三、氧在聚CoPP膜上电催化还原的研究 用RDE（旋转盘电极）方法比较了氧在聚CoPP/GC与吸附CoPP单体/GC上的电还原，发现聚CoPP膜的活性和稳定性都比吸附单体的高。聚合电位影响高聚物膜的稳定性。高聚物膜越厚，稳定性越好，并且随溶液pH值的降低而增大。高聚物膜厚度与其活性关系之间存在一个最佳值，低于或高于此值，其活性降低。在一定厚度范围内，氧电还原的Tafel斜率基本不变；其动力学反应常数(Kf)与电极表面上有效活性中心浓度(Pv')和乘积(Kf·Pv')随膜厚度的增加而降低。用RDE方法研究溶液pH值的影响时发现，在较宽的pH值范围内，聚CoPP/GC主要催化氧为二电子还原。聚CoPP膜的活性随溶液pH值的降低而增大。在低极化区内，氧在碱性溶液中或中性溶液中的电还原与OH~-浓度无关，而在酸性溶液中，H~+浓度有影响；在高极化区内，溶液pH值影响很小。RRDE（旋转环盘电极）的研究结果表明，在一定的电位范围内，氧在聚CoPP/PC上电还原的主要产物为H_2O_2，H_2O_2一但在盘电极上生成，就不再进一步还原，并同时体随有少量氧按四电子途径还原。若电位在很负的情况下，在盘上生成的H_2O_2能够进一步还原。根据以上的实验现象及结果我们提出了氧在聚CoPP膜上电催化还原的二电子还原机理、四电子还原机理和四电子的串联还原机理，并对上述实验现象的结果给予了一定的解释。

二氧化硫的阳极氧化

本文对贵金属电极和钴卟啉膜电极进行了动力学研究，并根据实验数据提出了SO_2在不同电极材料上的反应机理。一、各种电极材料催化性能的比较用循环伏安法得出SO_2在Pt、Au、Pd电极上的氧化在不同电位区有不同的机理。一种是在低电位区SO_2分子的直接放电，另一种是在高电位区表面吸附氧的化学氧化。在贵金属Ir、Ru、Rh电极上，So_2的氧化只有一种途径，即只能通过电极表面吸附氧的化学氧的化学氧化。根据SO_2在贵金属电极上氧化的峰电位得出SO_2在这些电极上的活性次序如下：Au > Ir > Pd，Ru > Pt > Rh SO_2在钴卟啉膜电极上氧化也只有一种途径，但和Ir、Ru、Rh电极不同，不是通过吸附氧的化学氧化，而是SO_2分子的直接放电。二、氧化机理1、SO_2在Au电极上电化学氧化机理 对SO_2在Au电极上电化学过程进行研究，用稳态极化曲线法测得在较负电位区Tafel线性区的斜率为0.049, 可说明SO_2分子第二个电子的脱除为控制步骤；用计时－电流法、计时－电位法求得SO_2在Au电极上电化学氧化的动力学参数R_6~o为10~(-11)数量级。测量不同电位下交流阻抗的频谱，得到两个明显的半园，表明电极过程包括了中间吸附物的形成。根据实验数据推导SO_2在Au电极上可能的电化学氧化机理如下：H_2SO_3 → H_2SO_3ads H_2(SO_3)_(ads) - e → H_2SO_3~+ H_2SO_3~+ +H_2O → HSO_3+H_3O~+ HSO_3 - e → HSO_3~+ HSO_3~+ + 2H_2O → H_2SO_4+H_3O~+ 2. So_2在Ru电极上的氧化机理在贵金属Ru电极上，SO_2通过吸附氧氧化，提出如下如能的反应机理：Ru + H_2O → Ru(OH)_(ads) + H~+ + e Ru(OH)_(ads) + H_2O → RuO_(ads) + H_3O~+ + e RuO_(ads) + SO_2 + H_2O → Ru + H_2SO_4用稳态法测得Tafel斜率为0.055，限制步骤可能为吸附氧氧化SO_2分子。3、SO_2 在Copp/Pt上的氧化机理在非金属钴卟啉膜电极上，SO_2氧化为SO_2分子的直接放电。稳态测量法得到极化曲线的Tafel斜率为0.107 (α=0.54)。表明SO_2分子的第一电子的脱除为控制步骤；计时－电位法表明SO_2在钴卟啉电极上氧化有个前置的化学反应p在不同电位下测量交流阻抗频谱也为两个半园，表明有中间吸附物形成。根据实验数据推导SO_2氧化的可能机理如下：H_2SO_3 → H_2SO_(3_(ads)) H_2SO_(3_(ads)) <-> H~+ + HSO_(3_(ads))~- HSO_(3_(ads))~- - e → HSO_3 HSO_3 - e → HSO_3~+ HSO_3~+ 2H_2O → H_2SO_4 + H_3O~+

硫化物矿物原电池腐蚀实验研究与应用启示

作为自然界最常见、可开发的矿物之一，硫化物矿物通常具有半导体性质，在溶液的作用下，必然发生原电池腐蚀。硫化物矿物原电池效应广泛存在并影响湿法冶金(如磨矿、浮选和浸出)、次生硫化物矿物过程、地电化学勘探、重金属离子污染和酸性矿山排水污染和治理等方面。 以前对硫化物矿物腐蚀研究多见于静止的溶液体系，少见于流动溶液体系，而实际情况是硫化物矿物经常处于流动溶液体系中。以矿山环境为例，硫化物矿物经常处于流动的地表水，地下水和雨水淋漓的环境体系中。因此，在流动体系中进行硫化物矿物原电池腐蚀实验研究，无疑对矿山环境治理有着直接的指导作用。另一方面，以前对于硫化物矿物原电池腐蚀的研究多是在无应力作用的条件下进行的，而事实上，无论是人类在开采利用硫化物矿物资源上，还是硫化物矿物本身在自然界的演化进程中，应力作用无时不在，无处不有。硫化物矿物应力原电池也无时不在，无处不有。应力作用下，应变能转化为电化学能，从而改变硫化物矿物的电极电位，必将进一步对硫化物矿物的原电池腐蚀产生重要影响。考察应力作用下的硫化物矿物原电池腐蚀，一方面可以为硫化物矿物的湿法冶金提供实验依据；另一方面，它将为硫化物矿物的元素活化、迁移、浓集和定位等各种地球化学作用解释提供理论指导。 鉴于硫化物矿物原电池腐蚀实验研究的重要意义以及前人对硫化物矿物原电池腐蚀研究在流动体系和应力作用等领域的研究空白，本论文展开了对上述领域的原电池腐蚀实验研究。 在本工作中，我们设计了一套用于溶液静止和溶液流动条件下的硫化物矿物原电池腐蚀实验装置。在流动条件下，对处在不同溶液组分(Na+、Cu2+、Fe3+)、浓度和流速的黄铁矿-黄铜矿、黄铁矿-方铅矿及应力残余黄铁矿-方铅矿原电池腐蚀进行了实验研究；设计了一套用于溶液静止条件下的硫化物矿物应力原电池腐蚀实验装置。展开了在不同溶液组分(Na+、Fe3+)及弹性轴压应力条件黄铁矿和黄铜矿腐蚀电位下的Tafel曲线及交流阻抗谱实验；在不同溶液组分(Na+、Fe3+)及差应力条件下黄铁矿-黄铜矿原电池混合电位下的Tafel曲线及交流阻抗谱实验。 实验结果表明： (1) 溶液中惰性离子(Na+)浓度的改变对原电池腐蚀电流密度和混合电位无明显影响；溶液中氧化性离子(Cu2+、Fe3+)浓度增大，原电池的腐蚀电流密度和混合电位增大。但是，当黄铁矿-黄铜矿原电池中氧化性离子为Cu2+时，增大Cu2+浓度，腐蚀电流密度先增大后减小，最后增大。 (2) 本实验条件下，溶液流速越大，腐蚀电流密度越大，混合电位增大。 (3) 应力残余黄铁矿由于残余应变能的缘故，其电极电位比处在相同条件的溶液下的方铅矿电极电位更低，应力残余黄铁矿-方铅矿原电池腐蚀情况与无应力的黄铁矿-方铅矿原电池腐蚀情况不同。 (4) 弹性轴压应力下，黄铁矿、黄铜矿电极电位和弹性轴压应力呈较好的负线性关系；黄铁矿、黄铜矿弹性轴压应力越大，腐蚀电位越小，腐蚀电流密度越大；电化学阻抗谱测试等效电路拟合的电极电荷传递电阻越小，极化电阻越小，双电层的离子迁移电阻越小，弥散效应越严重。 (5) 差应力作用下的黄铁矿-黄铜矿原电池腐蚀： 黄铜矿阳极弹性轴压应力越大，腐蚀电位越小，腐蚀电流密度越大；电化学阻抗谱测试等效电路拟合的电极电荷传递电阻越小，极化电阻越小，双电层的离子迁移电阻越小，弥散效应越严重。 黄铁矿阴极弹性轴压应力越大，腐蚀电位越大，腐蚀电流密度越小；电化学阻抗谱测试等效电路拟合的反应电阻越大，极化电阻越大，双电层的离子迁移电阻越大，弥散效应越轻微。 上述流动体系下的硫化物矿物原电池腐蚀结果可用Butler-Volmer方程结合原电池模型和双电层结构很好地解释；应力原电池腐蚀结果可用硫化物矿物半导体的热力学势、电化学势、力学应变能、结合原电池模型和双电层结构很好地解释。

A study of the oxygen electrochemistry of ruthenium and iridium

This thesis is concerned with an investigation of the anodic behaviour of ruthenium and iridium in aqueous solution and particularly of oxygen evolution on these metals. The latter process is of major interest in the large-scale production of hydrogen gas by the electrolysis of water. The presence of low levels of ruthenium trichloride ca. 10-4 mol dm-3 in acid solution give a considerable increase in the rate of oxygen evolution from platinum and gold, but not graphite, anodes. The mechanism of this catalytic effect was investigated using potential step and a.c. impedance technique. Earlier suggestions that the effect is due to catalysis by metal ions in solution were proved to be incorrect and it was shown that ruthenium species were incorporated into the surface oxide film. Changes in the oxidation state of these ruthenium species is probably responsible for the lowering of the oxygen overvoltage. Both the theoretical and practical aspects of the reaction were complicated by the fact that at constant potential the rates of both the catalysed and the uncatalysed oxygen evolution processes exhibit an appreciable, continuous decrease with either time or degree of oxidation of the substrate. The anodic behaviour of iridium in the oxide layer region has been investigated using conventional electrochemical techniques such as cyclic voltammetry. Applying a triangular voltage sweep at 10 Hz, 0.01 to 1.50V increases the amount of electric charge which the surface can store in the oxide region. This activation effect and the mechanism of charge storage is discussed in terms of both an expanded lattice theory for oxide growth on noble metals and a more recent theory of irreversible oxide formation with subsequent stoichiometry changes. The lack of hysteresis between the anodic and cathodic peaks at ca. 0.9 V suggests that the process involved here is proton migration in a relatively thick surface layer, i.e. that the reaction involved is some type of oxide-hydroxide transition. Lack of chloride ion inhibition in the anodic region also supports the irreversible oxide formation theory; however, to account for the hydrogen region of the potential sweep a compromise theory involving partial reduction of the outer regions of iridium oxide film is proposed. The loss of charge storage capacity when the activated iridium surface is anodized for a short time above ca. 1.60 V is attributed to loss by corrosion of the outer active layer from the metal surface. The behaviour of iridium at higher anodic potentials in acid solution was investigated. Current-time curves at constant potential and Tafel plots suggested that a change in the mechanism of the oxygen evolution reaction occurs at ca. 1.8 V. Above this potential, corrosion of the metal occurred, giving rise to an absorbance in the visible spectrum of the electrolyte (λ max = 455 nm). It is suggested that the species involved was Ir(O2)2+. A similar investigation in the case of alkaline electrolyte gave no evidence for a change in mechanism at 1.8 V and corrosion of the iridium was not observed. Oxygen evolution overpotentials were much lower for iridium than for platinum in both acidic and alkaline solutions.

Die Ortsnamen des Kreises Soest

Auf dem Gebiet des heutigen Kreises Soest sind über 400 Siedlungsnamen nachgewiesen worden, die vor 1600 erstmals schriftlich bezeugt sind. Diese Namen, die zum Teil ein sehr hohes Alter haben, werden im ersten Band des Westfälischen Ortsnamenbuches in ausgewählten historischen Belegen und mit einer wissenschaftlichen Deutung des Namens präsentiert. Damit ist zugleich ein Grundlagenwerk zur Namenlandschaft Westfalens entstanden, das auch für landes- und ortsgeschichtliche, kulturgeographische und genealogische Forschungen von Interesse ist.