pH值对海水中TMCP X80钢氢脆敏感性影响

采用氢渗透实验法、动电位极化法研究TMCP X80管线钢在不同pH值海水中的氢渗透行为,结合扫描电镜 (SEM) 观察研究显微组织及氢渗透行为对氢脆敏感性的影响。结果表明,随着海水pH值的减小,析氢电位发生正移。天然海水和酸性海水中氢扩散系数随着极化电位负移而增加;极化电流密度越大,氢扩散系数和氢浓度越大。在负于析氢电位时,显微形貌显示出明显的蚀坑和氢鼓泡,酸性海水中更严重。随着海水pH值的减小及外加阴极极化电位负移,氢扩散到材料内部的量更大;充氢电流密度增加也促进氢的扩散,X80钢氢脆敏感性增加。     

钛基镍钴合金电极的制备及析氢性能

目的降低电极的析氢过电位,提高析氢性能,从而降低电解水制氢的成本,促进氢储能技术的发展。方法通过异相共沉积法,制备了镍钴合金电极。利用场发射扫描电镜(SEM)、电化学交流阻抗(EIS)对纯镍电极及镍钴合金电极进行表征,采用阴极极化曲线(LSV)探究了电沉积液中Ni/Co元素的比例、电沉积电位及电沉积时间对镍钴合金电极析氢性能的影响。结果 SEM结果揭示了纯镍电极及镍钴合金电极表面分别是粒径约为100 nm左右的镍颗粒和镍钴颗粒。EIS结果说明了镍钴合金电极的导电性能优于纯镍电极。此外,纯镍电极、镍钴合金电极的阴极极化曲线测试表明在电流密度为30 mA/cm~2时,镍钴合金电极的析氢过电位比纯镍电极降低55 mV,降低了近20%。结论通过异相共沉积法制备镍钴合金电极,制备方法简单、方便、快速,其析氢性能优于纯镍电极。镍钴合金电极的最优制备工艺条件为:NiSO_4·6H_2O 27 g/L,CoSO_4·7H_2O_3 g/L,H_3BO_3 10 g/L,Na_2SO_4 10 g/L,柠檬酸10 g/L,十二烷基硫酸钠0.1 g/L,pH值4.0,电沉积电位-1.3 V,电沉积时间10 s。     

电沉积法制备泡沫Ni-Mo-Co合金

本文以聚氨酯泡沫海绵为基体,经导电层的制备、电镀和热解还原工艺制备出了泡沫Ni-Mo-Co三元合金.采用扫描电子显微镜(SEM)和X射线衍射技术(XRD)分别研究了化学镀镍后及电镀Ni-Mo-Co合金的表面形貌、元素组成和晶态结构,并用稳态极化曲线研究了泡沫Ni-Mo-Co合金电极在30%KOH溶液中的析氢催化性能.结...     

Pt-ZrO2/Ti电极在酸性介质中的电催化析氢性能

在研究钛基复合镀Pt-ZrO2电极镀层性能、碱性介质中电催化性能的基础上, 为了试验电极在酸性介质中是否也有电催化作用及影响电催化作用的因素,再一次通过复合电沉积技术制备出Pt-ZrO2/Ti电极,用扫描电镜观察了电极表面形貌,进行了电极在0.5mol/L硫酸介质中的阴极极化曲线实验.结果表明,Pt-ZrO2/Ti电极在酸性介质中也有电催化作用且电催化析氢性能高于Pt/Ti电极,性能的提高除了较小的电阻外,较大的表面粗糙度是一个重要因素.用该复合电极代替铂电极使用,在性能和经济上来说具有一定的意义.     

Electrocatalytic activity and electrochemical hydrogen storage of Ni-La alloy prepared by electrodeposition from aqueous electrolyte

Ni-La alloy coating was prepared by electrodeposition. The effect of cathodic current density on the La content of the alloy coatings was discussed. It is found that the content of La in the alloy increases with increasing the cathodic current density. The microstructures and codeposition mechanism of Ni-La alloy coatings were investigated by means of X-ray diffraction (XRD) and cyclic voltammetry (CV). The results demonstrate that the Ni-La alloy is FCC and codeposited by the induced mechanism. The hydrogen evolution reaction (HER) on the electrodeposited Ni-La alloy electrodes in alkaline solution was evaluated by Tafel polarization curves. It is found that La-Ni alloy coating exhibites much higher exchange current density for HER than pure Ni electrode, and that the exchange current density increases with increasing the La content of alloys. The good electrocatalytic activity for HER of this Ni-La alloy is attributed to the synergism of the electronic structure of La and Ni. The electrodeposited La-Ni alloys have a certain dectrochemical hydrogen storage capacity of 34- 143 mAh/g, which increases with increasing the La content of alloys.     

Ni-Cr-Mo-Cu多孔磷化物电极的制备及电催化析氢性能研究

为了解决电解水析氢过程中所用电极材料的低效率、高成本问题,采用粉末冶金法—低温磷化法制备了一种Ni-Cr-Mo-Cu多孔磷化物电极。采用X射线衍射分析(XRD)、场发射电镜(SEM)、X射线能谱分析(EDS)等对电极的物相、形貌结构以及元素分布等进行表征;通过开路电位、线性极化、交流阻抗等方法测试了磷化物电极材料的电催化析氢性能。结果表明Ni-Cr-Mo-,Cu多孔磷化物电极具有优异的析氢性能,调节磷化时间可在较大程度上提高其析氢催化活性。在室温条件下,磷化时间为2小时的Ni-Cr-Mo-Cu多孔磷化物电极在6mol/L KOH的溶液中析氢性能较好,其析氢过电位仅有-0.19V (vs RHE),交换电流密度为10mA/cm2时对应的极化电位为-0.20V (vs RHE);经开路电位测试18000s后,电极材料的开路电位 (η) 从+0.80变化为0.78V (vs RHE),仅降低0.02 V,表明其具有良好的电催化稳定性。     

Pb-0.3%Ag/Pb-CeO2复合阳极材料电化学性能

采用双脉冲电沉积,在Pb-0.3%Ag(质量分数,下同)合金基体表面制备了Pb-0.3%Ag/Pb-CeO2复合阳极材料,研究了不同正向脉冲平均电流密度(2~5 A·dm-2)和镀液中CeO2颗粒浓度(0~20 g/L)下制备的复合阳极材料电化性能,在50 g·L-1 Zn2+,150 g·L-1 H2SO4,35℃溶液中测试了阳极极化曲线、循环伏安曲线和塔菲尔曲线,获得了析氧动力学参数、伏安电荷、腐蚀电位和腐蚀电流。结果表明:在正向脉冲平均电流密度为3 A/dm2和镀液中CeO2颗粒浓度为15 g/L下制备的Pb-0.3%Ag/Pb-CeO2复合阳极材料在[ZnSO4+H2SO4]溶液中具有较高的电催化活性,较低的析氧过电位,较好的电极反应可逆性和耐腐蚀性。在[ZnSO4+H2SO4]溶液中,复合阳极材料在测试电流密度500 A/m2下的析氧过电位为1.134V,比Pb-1%Ag合金降低37 mV;腐蚀电流为1.97×10-4 A,明显低于Pb-1%Ag合金,表现出了良好的耐腐蚀性能。     

A new method to improve surface morphology of Ni-Fe-Mo-Co alloy electrode and its catalytic activity for HER

A new pretreatment method has been developed to improve the catalytic activity of the Ni-Fe-Mo-Co alloy elec- trode for hydrogen evolution reaction (HER). The procedure involves pre-electrolyzing the Ni-Fe-Mo-Co alloy electrode in 30% KOH solution containing 10% potassium sodium tartrate at 70°C for 2 h, until some of the Mo and Fe elements are leached out. The surface morphology of the Ni-Fe-Mo-Co alloy demonstrates a unique hive-like structure after the pre- treatment, which has the pore size in a nanometer range (about 50 nm), a very large real surface area, and good stability. The results of the electrochemical studies show that compared to other similar electrode materials and the treated Ni-Fe-Mo-Co electrode by leaching method, the pre-treated Ni-Fe-Mo-Co electrode has a much lower overpotential and much higher exchange current density for HER. In addition, a long-term continuous electrolysis test with a current interrup- tion shows that the Ni-Fe-Mo-Co alloy has excellent catalytic stability.     

Influences of Iridium and Palladium on Oxidation Resistance of PtAl Coating

The overarching goal of present study is to investigate the effects of Ir and Pd additions on the oxidation behaviour of PtAl coatings. Prior to depositing standard PtAl coating, Ir layer was electroplated by IrBr 3 aqueous solution while Pd layer was prepared using electroless deposition. Comparing with normal PtAl coating, cyclic oxidation tests were carried out on both the Ir-and Pd-modified aluminide coatings. The results showed that Ir-modified PtAl coating exhibited better oxidation resistance than both Pd-modified and normal PtAl coatings because Ir partly served as diffusion barrier to reserve Al while Pd did not.     

Surface structure and catalytic activity of electrodeposited Ni-Fe-Co-Mo alloy electrode by partially leaching Mo and Fe

1 Introduction The chlorine alkaline industry and the production of hydrogen by electrolyzing water have disadvantages of high cost and energy consumption, so it is especially important to study and develop a high catalytic activity and good stability el…     

Hydrogen desorption kinetics of amorphous Mg0.9Ti0. 1Ni1-xPdx （x=0, 0.05, 0.1 and 0.15） electrode alloys

1 Introduction Mg-based alloy is a kind of promising hydrogen storage materials used for fuel cell. It is also a potential candidate as cathode materials of Ni-MH rechargeable batteries due to its large discharge capacity[1]. However, its cyclic stabilit…     

Electrocatalytic behaviour of NiBi coatings for hydrogen evolution reaction in alkaline medium

The nickel-bismuth binary coatings with various chemical compositions were galvanostatically deposited on the copper electrode in view of their possible applications as electrocatalytic materials for the hydrogen evolution reaction (HER) in alkaline solution. The HER activity of coatings was tested with the help of potentiodynamic measurements and electrochemical impedance spectroscopy (EIS) technique. The electrochemical characterization was achieved by the means of cyclic voltammetry (CV). The surface morphology and surface composition of coatings were determined with scanning electron microscopy (SEM), and energy dispersive X-ray (EDX). The potentiodynamic measurements show that, the binary coatings decrease the hydrogen over potential and increase the current density values for HER. The EIS analysis confirms, the charge transfer resistances decrease and the double layer capacitance values increase for binary coatings. The EDX results in sign that the composition of binary coating changes by using coating bath. The Cu/NiBi-2 coating (Ni²⁺/Bi³⁺ is 99.71:0.29 molar ratio) is the best suitable cathode composition for the HER in alkaline media under these experimental conditions.     

电沉积Ni-S合金作碱液电解活性阴极的研究进展

电沉积Ni-S合金作为碱液电解阴极材料,具有很高的析氢反应活性,能够降低析氢反应的过电位.基于文献调研并结合作者的工作,归纳了Ni-S合金的制备、晶体结构、析氢反应活性及其析氢反应机理等方面的研究状况.     

阴极极化下X80钢在鹰潭土壤模拟溶液中应力腐蚀行为研究

采用电化学阻抗和慢应变速率方法,结合扫描电子显微镜,研究了不同阴极极化电位下X80钢在鹰潭土壤模拟溶液中的应力腐蚀行为。结果表明：鹰潭土壤模拟溶液中,X80钢/溶液界面处电荷转移电阻随阴极极化程度增加先升后降。在自腐蚀电位条件下开裂机理为阳极溶解,当外加电位为-1000 mV (vs SCE),应力腐蚀敏感性最低,此电位为最佳保护电位;继续增大阴极极化程度,应力腐蚀敏感性增加,此时开裂机制为氢和应力协同作用下的氢致开裂。     

Electrocatalytic properties of Ni-S-Co coating electrode for hydrogen evolution in alkaline medium

Amorphous Ni-S-Co alloy was prepared by means of chemical electro-deposition method on the foam nickel matrix. The surface morphology and microstructure of Ni-S-Co coatings were studied usmg SEM and XRD, and the electrochemical properties were tested by electrochemical methods. The results show that the coating has amorphous structure and the particles of the surface are fine with large specific surface area. The Ni-S-Co alloy is more active with lower potential for hydrogen evolution, higher exchange current density and lower activation energy compared with Ni and Ni-S electrode. Its hydrogen evolution reaction（HER） is enhanced, the size of particles of surface decreases and the surface area increases after being activated by KOH alkaline solution.     

Production and electrochemical characterization of Ni-based composite coatings containing titanium, vanadium or molybdenum powders

Composite Ni + Ti, Ni + V and Ni + Mo coatings were prepared by codeposition of Ti, V or Mo particles in an Ni matrix on a carbon steel substrate from the nickel bath in which metallic powder was held in suspension. The influence of the metal powder amount in the bath, as well as the deposition current density on chemical composition of obtained coatings has been investigated. It was stated that the content of incorporated Ti, V and Mo increases with the increase in the particle concentration in the electrolyte, and diminishes with the increase in the deposition current density. The mechanism of metallic particles embedding was explained on the base of Ni²⁺ ions adsorption process. Deposits exhibited a presence of Ti, V or Mo microsize particles embedded into the nanocrystalline nickel matrix. Incorporation of metallic powder into electrolytic nickel matrix results in the significant increase in the real surface area of the deposits. Electrodeposited composite coatings were tested as electrode materials for hydrogen evolution reaction (HER) in an alkaline environment. Electrochemical characterization was carried out by steady-state polarization method. All composite materials showed enhanced electrochemical activity for HER compared to the nickel electrode. Based on determined values of exchange current density-j₀ and the values of hydrogen evolution overpotential at 100 mA cm^− 2-η₁₀₀ the variation in the electrochemical activity of Ni + Ti, Ni + V and Ni + Mo composites in dependence on their chemical composition and the kind of incorporated component was evaluated. Comparison of the investigated materials leads to the statement that the highest activity towards the HER exhibit Ni + Mo deposits.     

CO2环境下温度和S2-对X60管线钢电化学行为的影响

利用极化曲线和电化学阻抗测试研究了温度和硫离子对X60管线钢CO2腐蚀电化学行为的影响。结果表明,在温度和硫离子交互作用下,随温度的升高腐蚀电流密度不断增大。S2-加入后电极表面生成一层黑色的腐蚀产物膜,随着S2-浓度的升高,腐蚀电位明显负移,腐蚀电流密度呈现下降-上升-下降的趋势,电极过程主要受硫化物生长过程控制。     

冷轧带钢电解清洗极板腐蚀机理和原因

采用线性电位扫描法研究了碳钢在不同脱脂剂浓度下的阳极极化过程,进一步研究了碳钢在不同不同脱脂剂浓度条件下、不同电位下的恒电位、恒电流电解行为,在此基础上对生产现场进行了考察。电化学实验表明：碳钢阳极极化过程依次经历活化区、钝化区、过钝化区及极限区;活化区基体活化溶解电流小,不影响电极寿命;过钝化区电极表面开始发生析氧反应;极限区析氧反应达到极限,使基体腐蚀反应大量发生,电极寿命降低;脱脂剂浓度越低、阳极电位越高,电极表面基体溶解反应速率越大,相应电极使用寿命越短。实际生产中,极板表面由于电流分布不均使其局部电流超过极限电流导致局部腐蚀发生,而电解槽内极板安装精度、电极表面气泡无法逸出、极板表面污泥淤积等都均会影响电流分布。     

Electrochemical Properties of Pulse Plating Amorphous Ni-Mo-W Alloy Coating in Alkaline Medium

采用脉冲电镀技术获得了高活性Ni-Mo-W析氢合金阴极。以析氢反应过电位为考察指标,确定了脉冲镀Ni-Mo-W合金的最佳电镀条件,如Na2WO4·2H2O浓度、平均电流密度和占空比等。同时,系统研究了Mo和W含量对Ni-Mo-W合金镀层成分和组成的影响规律。结果表明,在二元合金中添加W能有效提高电极的析氢反应活性(η200＝80 mV);非晶态Ni-Mo-W合金的组织结构主要取决于Mo含量;与非晶态Ni-Mo合金镀层相比,Ni-Mo-W合金析氢阴极的电化学稳定性得到一定程度的提高。     

Hydrogen overvoltage at manganese in ammonium-bromide-perchloric solution

Kinetic characteristics of electrochemical hydrogen evolution at manganese rotating disc electrode in ammonium-bromide-perchloric solution at 18, 40, and 60°C are determined (the overvoltage, Tafel slopes, exchange currents, and activation energy). The zero-charge potential is found. Mechanism of the electrode process is suggested. It is shown that S-shaped bends in the polarization curves of hydrogen evolution can be entailed with changes in the electrode surface charge. The overvoltage and current density corresponding to beginning of the activationless range of electrochemical hydrogen evolution are determined.