酸性溶液中氯离子对铁的钝化膜的破坏

0.5 mol L~(-1)H_2SO_4溶液中高纯铁电极在短时间阳极钝化后再向阴极方向扫描时可测出阴极还原电量, 这主要是由于氧化膜的还原引起的, 极少量Cl~-能使阴极还原电量明显减少。Cl~-的主要作用是阻滞钝化膜的形成并使钝化膜稳定性下降。     

电解还原法合成间苯二胺

在酸性介质中以铜为阴极、石墨为阳极电解还原间二硝基苯制备间苯二胺。考查了温度、电流密度、间二硝基苯用量和盐酸质量百分数对间苯二胺产率的影响及电量对电流效率的影响 ,正交实验确定反应的最佳条件为 :温度 4 0℃ ,电流密度 4A·dm- 2 ,间二硝基苯 0 .2 5g ,HCl质量百分数 15 %。在最佳条件下 ,间苯二胺的产率达 74 .2 %。     

季阳离子基团对聚吡咯膜伏安特性的影响

在含有相同阴离子与不同阳离子基团的电解质溶液中用电位阶跃技术制备了聚吡咯(PPy)膜，用循环伏安法于空白溶液中研究了膜的电化学行为。研究结果表明随着阳离子基团增大，制膜时消耗的电量减小，膜的氧化还原电流下降，阴极和阳极峰电位分别向更负和更正的方向移动。扫描电镜显示阳离子基团对PPy膜的沉积过程和形态结构产生了一定的影响。     

丁二酸在Ti/TiO2膜电极上的电化学合成

在包含原料马来酸的硫酸溶液中, 通过原位阳极氧化法制备了Ti/TiO2膜电极, 然后采用极性转换技术在原溶液中电化学合成丁二酸. 采用XPS, XRD和SEM分析了膜电极上的元素组成、价态分布和氧化膜的晶相结构及表面形貌. 结果表明, 阳极氧化膜层内只含有Ti和O两种元素, 且Ti均为Ti4+; TiO2氧化膜是金红石相, 表观呈现带孔的条纹形貌. 通过循环伏安、恒电位阶跃和恒电流电解技术研究了Ti/TiO2原位氧化膜电极的电化学性质, 结果表明, 该膜电极对马来酸电还原合成丁二酸具有较好的电催化活性. 以钛基氧化钌电极(DSA)为阳极, Ti/TiO2原位氧化膜电极为阴极进行恒电流电解了实验. 结果表明, 丁二酸的还原产率为95.94%, 电流效率为95.57%, 产物纯度为99.28%, 熔点为185~187 ℃.     

非化学计量的混合价态氧化钼(VI,V)修饰微电极的电化学制备

在新鲜配制的Na2MoO4的弱酸性水溶液中, 通过循环电位扫描在碳纤维微电极表面可沉积一层均匀的蓝色氧化钼(VI, V)薄膜, 膜的厚度通过电量进行控制。在电沉积之前, 电极的阳极化处理不仅可以加快氧化钼的电沉积, 而且可以改善膜的伏安行为。溶液的pH值对膜的电沉积和伏安行为有极大的影响。膜的阴极过程被认为是产生青钼铜: HxMoO3 (0相似文献   

非化学计量的混合价态氧化钼(Ⅵ,Ⅴ)修饰微电极的电化学制备

在新鲜配制的Na_2MoO_4的弱酸性水溶液中,通过循环电位扫描在碳纤维微电极表面可沉积一层均匀的蓝色氧化钼(VI,V)薄膜,膜的厚度通过电量进行控制.在电沉积之前,电极的阳极化处理不仅可以加快氧化钼的电沉积,而且可以改善膜的伏安行为.溶液的pH值对膜的电沉积和伏安行为有极大的影响.膜的阴极过程被认为是产生青钼铜:H_xMoO_3(0相似文献   

以次磷酸钠为还原剂化学镀铜的电化学研究

通过电化学方法研究了以次磷酸钠为还原剂, 柠檬酸钠为络合剂的化学镀铜体系. 应用线性扫描伏安法, 检测了温度、pH值、镍离子含量对次磷酸钠阳极氧化和铜离子阴极还原的影响. 结果表明, 升高温度能够加速阳极氧化与阴极还原过程; pH值的提高可促进次磷酸钠氧化, 但抑制铜离子还原; 镍离子的存在不仅对次磷酸钠的氧化有强烈的催化作用, 而且与铜共沉积形成合金. 该合金有催化活性, 使化学镀铜反应得以持续进行.     

铅锑合金在硫酸溶液中的阳极膜II.电位对阳极膜生长的影响

本文使用线性电位扫描法还原预恒电位法氧化形成的阳极膜,研究电位对Pb-7Sb,Pb-7Sb-0.3Ag和Pb-5Sb-0.2As三种合金在30℃,4.5MH2SO4溶液中的阳极膜的生长速度的影响,在铅锑合金中添加银可降低合金阳极膜的生长速度,但在高电位1.4V(vs.Hg2SO4电极时,Pb-7Sb-0.3Ag合金上的PbO2膜的生长速度在上述三合金中居首,这可能是由于在银上的氧析出超电势较低的缘故,本文讨论了这种阳极膜的生长机理。     

苄醇的选择性间接电氧化

以Ｃｅ￣（４＋）／Ｃｅ￣（３＋）为氧化还原体系，以硫酸为支持电解质，采用槽内法研究了苄醇的选择性间接电氧化。得出最佳电解条件：电流密度，０．１Ａ／２０ｃｍ￣２；亚铈与反应物当量比，１：６；硫酸浓度，３ｍｏｌ／Ｌ；通过电量，２Ｆ／ｍｏｌ（Ｆ为理论电量）。在最佳电解条件下，反应产物为苯甲醛，产率高达９６％，不发生深度氧化。阳极液循环１０次以上，对反应产率无影响。反应中Ｃｅ￣（４＋）只起电子传递作用，反应仅消耗电能，因此此法十分经济，且无污染。     

铅锑合金在硫酸溶液中的阳极膜-——Ⅱ.电位对阳极膜生长的影响

本文使用线性电位扫描法还原预恒电位法氧化形成的阳极膜,研究电位对Pb-7Sb,Pb-7Sb-0.3Ag和Pb-5Sb-0.2As三种合金在30℃,4.5MH_2SO_4溶液中的阳极膜的生长速度的影响。在铅锑合金中添加银可降低合金阳极膜的生长速度。但在高电位1.4V(vs.Hg_2SO_4电极)时,Pb-7Sb-0.3Ag合金上的PbO_2膜的生长速度在上述三合金中居首,这可能是由于在银上的氧析出超电势较低的缘故。本文还讨论了这种阳极膜的生长机理。     

Tunable Syngas Production from CO2 and H2O in an Aqueous Photoelectrochemical Cell

Syngas, the mixture of CO and H₂, is a key feedstock to produce methanol and liquid fuels in industry, yet limited success has been made to develop clean syngas production using renewable solar energy. We demonstrated that syngas with a benchmark turnover number of 1330 and a desirable CO/H₂ ratio of 1:2 could be attained from photoelectrochemical CO₂ and H₂O reduction in an aqueous medium by exploiting the synergistic co‐catalytic effect between Cu and ZnO. The CO/H₂ ratio in the syngas products was tuned in a large range between 2:1 and 1:4 with a total unity Faradaic efficiency. Moreover, a high Faradaic efficiency of 70 % for CO was acheived at underpotential of 180 mV, which is the lowest potential ever reported in an aqueous photoelectrochemical cell. It was found that the combination of Cu and ZnO offered complementary chemical properties that lead to special reaction channels not seen in Cu, or ZnO alone.     

Enrichment,incorporation and oxidation of copper during anodising of aluminium–copper alloys

Porous anodic oxides generated on copper‐containing aluminium alloys are less regular than anodic oxides generated on pure aluminium. Specifically, a porous oxide morphology comprising layers of embryo pores, generated by a cyclic process of oxide film growth and oxygen evolution, is generally observed. In this work, the relation between the oxidation behaviour of copper during anodising and the specific porous oxide film morphology was investigated by electrochemical techniques, transmission electron microscopy and Rutherford backscattering spectroscopy (RBS). It was found that the anodising potential determines the oxidation behaviour of copper, and the latter determines the porous oxide morphology. At low voltage, relatively straight pores with continuous cell walls were obtained on Al? Cu alloys, but selective oxidation of aluminium atoms resulted in the occlusion of copper‐containing metallic nanoparticles in the anodic film. At higher potentials, copper oxidation promoted oxygen evolution within the barrier layer, and generation of a less regular film morphology. RBS, performed on Al? Cu alloy specimens, revealed a high volume fraction of copper atoms in the anodic films generated at low potentials and a reduced amount of copper atoms in the anodic oxide films generated at high potentials. Copyright © 2009 John Wiley & Sons, Ltd.     

复方钨酸盐对铜缓蚀协同作用的光电化学和SERS 研究

主要采用光电化学方法和表面增强拉曼光谱技术对具有环境友好性的钨酸盐与BTA复配使用对铜的缓蚀协同效应和作用机理进行了研究。实验表明Na2WO4对铜的缓蚀作用机理与BTA不同,在电位正向扫描过程中,光电流并不发生转型,其大小变化也不大;但在电位负向扫描过程中产生的阴极光电流峰值明显增大,缓蚀剂浓度越大,光电流越大,缓蚀效果越好,而Na2WO4与BTA复配使用时具有较好的协同效应,光电化学和SERS结果都说明其协同机理为两者都能对铜的缓蚀产生作用,前暑能促使电极表面产生的铜的氧化物增多;后者能与铜(Ⅰ)生成聚合物膜。     

钛表面二氧化钛膜中氧空位点缺陷传输性能的电化学研究

"钛/TiO2氧化膜/溶液"界面电极体系的电化学性能主要决定于钛表面的TiO2氧化物膜.本文利用多种电化学技术,结合半导体物理的Mott-Schottky分析和Einstein方程,研究了金属钛在1.0mol·L-1HClO4溶液中表面半导体TiO2氧化膜的生长及氧化膜中氧空位点缺陷在外加电场作用下的传输性能,并根据离子性电荷传输与电子性电荷传输对电场变化响应时间之不同特点,确定氧化膜中点缺陷扩散系数.结果表明,电极电位或阳极析氧反应对稳态电流(iss)、氧化膜的阳极化常数(α)、膜中电场强度()、以及膜中氧空位点缺陷的扩散系数(D0)等重要物理化学参数,均有显著影响,并依据氧化膜中的结构变化进行分析.     

Electrochemical and surface analytical study of the formation of oxide films on monel-400 and copper in alkaline media

The nature of the oxide films formed on monel-400 and copper in presence of NaOH and N-methylpyrrolidine (a volatile amine) at pH 9.5 and in 0.1 M KNO₃ medium were investigated. The oxide films were grown by applying an anodic potential of +0.4 V (vs saturated calomel electrode) for 30 min. The compositions of the surface oxide films were analysed by X-ray photoelectron spectroscopy. In the case of copper in NaOH medium, Cu(0) and a very small amount of copper hydroxide were observed. However, in amine medium, Cu(0) and Cu-amine complex were found. For monel in NaOH, the anodic film was found to contain hydroxides of both copper and nickel. After sputtering, this film showed a small amount of metal oxide below the hydroxide layer as confirmed by the oxygen peak. In amine medium the anodic film was found to contain only nickel hydroxide and metallic copper. The depth profile analysis of films showed that the film developed was very thin and the nickel hydroxide was sputtered very easily from the film. Received: 27 May 1997 / Accepted: 8 September 1997     

Facile electrochemical growth of nanostructured copper phthalocyanine thin film via simultaneous anodic oxidation of copper and dilithium phthalocyanine for photoelectrochemical hydrogen evolution

We present a novel electrochemical approach to grow copper phthalocyanine (CuPc) thin-film photoelectrodes through anodic oxidation of copper and dilithium phthalocyanine (Li₂Pc). This circumvents the challenges associated with the electrochemical processing of unsubstituted CuPc from solution. The potentiostatic co-electrooxidation reaction at the heterogeneous interface favors the growth of CuPc thin film. The surface morphology of thin film exhibits nanorod-like features. UV-Vis, grazing angle Fourier transform infrared (FTIR), and grazing angle X-ray diffraction patterns reveal that the nanocrystalline phase corresponds only to α-CuPc and no admixture of other polymorphs. Photocurrent measurement shows a stable photoresponse in neutral medium. The photoelectrochemical hydrogen evolution on p-type CuPc coated copper photocathode shows an enhanced activity over bare copper and indium tin oxide (ITO) electrodeposited with CuPc and monolithium phthalocyanine radical (LiPc) thin films.     

阳极氧化水解法制备TiO2纳米膜

TiO2在光电化学电池领域已成为比较重要的半导体材料，自从1972年，Fuishima和Honda首次把TiO2电极用于光电解水以来，人们已经使用多种方法，如化学气相沉积、TiO2粉的烧结、RF射频溅射、等离子体喷涂或用胶体TiO2涂膜等各种方法，来制备单晶（金红石），多晶（金红石、锐钛矿     

Electrocatalytic reduction of carbon dioxide over reduced nanoporous zinc oxide

Nanoporous zinc oxide (ZnO) is prepared by a hydrothermal method followed by thermal decomposition for electrocatalytic reduction of CO₂. In situ X-ray absorption spectroscopy results indicate that ZnO is reduced to Zn under the electrolysis conditions for catalyzing CO₂ electroreduction. The reduced nanoporous ZnO exhibits obviously higher CO Faradaic efficiency and current density than commercial Zn foil with a maximum CO Faradaic efficiency of 92.0%, suggesting that the nanoporous structure facilitates electrocatalytic reduction of CO₂ over reduced nanoporous ZnO, probably due to increased surface area and more coordination unsaturated surface atoms.     

Self‐powered Photoelectrochemical Sensor for Gallic Acid Exploiting a CdSe/ZnS Core‐shell Quantum Dot Sensitized TiO2 as Photoanode

Herein is described the development of a self‐powered sensor for gallic acid (GA) determination exploiting CdSe/ZnS quantum dot sensitized TiO₂ nanoparticles (CdSe/ZnS/TiO₂/FTO) as photoanode and an all copper oxide photocathode (CuO/Cu₂O/FTO) to reduce water. A two‐chamber self‐powered photoelectrochemical cell was employed in order to maintain separated the photoelectrodes. The self‐powered photoelectrochemical cell is based on water reduction in the cathodic chamber while gallic acid acts as a hole scavenger in the anodic chamber to generate the necessary cell output to drive GA oxidation in the anodic compartment. Electrochemical impedance measurements were performed to evaluate the electronic characteristics of CdSe/ZnS/TiO₂/FTO photoanode and CuO/Cu₂O/FTO photocathode in terms of flat band potential, carrier density, and nature of semiconductor. Under optimized conditions, the self‐powered photoelectrochemical cell presented a wide linear response range for GA from 1 μmol L⁻¹ up to 200 μmol L⁻¹.     

Copper oxides: kinetics of formation and semiconducting properties. Part I. Polycrystalline copper and copper-gold alloys

The anodic formation of Cu(I) and Cu(II) oxides on polycrystalline copper and copper-gold alloys (4 and 15 at% Au) in deoxygenated 0.1 M KOH was examined by voltammetry, chronoamperometry, and chronopotentiometry with a synchronous registration of photocurrent and photopotential, in situ spectroscopy of photocurrent as well as XPS and SEM measurements. The band gap of p-Cu₂O is 2.2 eV for indirect optical transitions independent of the concentration of gold in Cu-Au alloy. It grows on CuOH or n-Cu₂O underlayer. The increase of anodic potential results in a thickening of oxide film which is a mixture of Cu(I) and Cu(II) oxides. The latter is a p-type semiconductor with a low photosensitivity. The rate of oxide formation on the alloys is lower than on copper. The structure-dependent properties of the oxide phase on the alloys and copper are different. Copper is prone to corrosive oxidation even in deoxygenated alkaline solution by the traces of molecular oxygen. The corrosive growth of Cu(I) oxide film occurs according to the parabolic law. After the cathodic polarization, the surface of copper remains free of corrosive oxide no longer than 15–20 min. The preliminary anodic formation even of a thin Cu₂O film as well as the alloying of copper with gold suppresses the corrosive oxidation of copper.