电沉积工艺参数对镍-钼-锌三元合金电极析氢催化性能的影响

目的采用直流电沉积法在铜基底上制备镍-钼-锌三元合金电极,提高电解水析氢过程中阴极电极的效率。方法使用电化学工作站研究不同电沉积工艺参数对镍-钼-锌三元合金镀层析氢性能的影响,使用扫描电镜(SEM)、X射线衍射分析仪(XRD)、能谱仪(EDS)对合金镀层表面形貌、相结构及元素含量进行表征。通过线性扫描伏安法(LSV)对析氢过电位进行测量,采用塔菲尔极化获得塔菲尔斜率,采用电化学阻抗法(EIS)表征合金镀层的析氢催化性能。结果最佳工艺参数为:温度45℃,p H=10.5,电流密度100 mA/cm~2。该合金在10 mA/cm~2下相对氢标电位仅为139 mV,塔菲尔斜率为103 mV/dec,活化电极电阻(Rct)随着电压的升高而降低。合金中Ni、Mo和Zn的原子比分别为68.23%、10.09%和21.68%。合金镀层为非晶结构,表面是纳米级颗粒堆叠而成的粗糙形貌。结论不同的工艺参数对Ni-Mo-Zn电极析氢性能有着重大影响,其析氢性能随着p H值的升高而上升,随着电流密度的升高而先增后减,随着电沉积温度的升高而上升。Ni-Mo-Zn高的析氢性能源于其元素协同作用、非晶结构和粗糙表面。     

钛基Ni-Co-P非晶合金镀层电极的析氢性能

通过电沉积在钛基体上制备了非晶态Ni-Co-P合金镀层.在7mol/L NaOH溶液中进行的电化学测试结果表明,Ni-Co-P合金电极的析氢过电位明显低于镀镍阴极和纯钛阴极;计算了电极析氢反应的电化学动力学参数,表明非晶态Ni-Co-P合金电极具有较好的析氢电催化活性.     

电沉积Ni-Fe-P非晶合金析氢阴极材料及其去合金化处理

目的 提高Fe电极的催化析氢性能。方法 较低温度条件下,在Fe基体表面电沉积一层非晶态Ni-Fe-P镀层,探究沉积电流密度、去合金时间等参数对Ni-Fe-P/Fe电极在碱性电解质中的电催化析氢反应的影响。通过扫描电镜、能谱、X射线衍射对镀层的形貌、元素分布、物相进行分析。在碱性溶液中,利用电化学工作站对电极进行一系列性能测试。结果 在沉积温度为10 ℃的条件下,于Fe电极表面成功制备出了致密且元素分布均匀的Ni-Fe-P非晶合金镀层。获得的Ni-Fe-P/Fe电极电催化性能均优于Fe电极,其中电流密度30 mA/cm2条件下制备的Ni-Fe-P/Fe电极在析氢电流密度为10 mA/cm2时的过电位为174.2 mV,比Fe电极低约466.2 mV。在相同条件下制备的Ni-Fe-P/Fe电极,经240 s去合金化处理,电极过电位仅为121.6 mV,比Fe电极低约518.8 mV。结论 电沉积的Ni-Fe-P非晶合金镀层可以显著提高Fe电极的析氢性能。随着沉积电流密度的增加,Ni-Fe-P/Fe电极的析氢过电位减小,双电层电容和电化学工作表面积增大。对镀层进行适当的去合金化处理,形成的三维多孔结构可以减小电极的电荷转移电阻,有效降低电极的析氢过电位。     

一步电沉积法制备Ni-Mo-Nd/NF复合电极及其析氢性能研究

目的 采用一步恒电流沉积法在泡沫镍基底上制备出镍-钼-钕三元析氢电极,提高碱性条件下的析氢性能。方法 使用电化学工作站研究工艺参数对Ni-Mo-Nd/NF析氢电极性能的影响,同时制备Ni-Mo/NF析氢电极,使用扫描电镜(SEM)、X射线衍射分析仪(XRD)、能谱仪(EDS)和X射线光电子能谱(XPS)对合金镀层表面形貌、相结构、元素含量及成键状态进行表征。通过线性扫描伏安法(LSV)、循环伏安法(CV)及电化学阻抗技术(EIS)测试电极析氢性能。结果 最佳工艺参数为:pH=4.5,电流密度30 mA/cm²,沉积时间60 min,温度30 ℃。在1.0 mol/L KOH溶液中,Ni-Mo-Nd/NF电极在10 mA/cm²下的析氢过电位仅为73 mV,Tafel斜率为147 mV/dec,表明析氢反应机理遵循典型的Volmer-Heyrovsky步骤。此外,Ni-Mo-Nd/NF电极在长时电解24 h时电流密度保持稳定,2 000次循环伏安测试后,催化剂的活性衰减微小。结论 稀土元素Nd的掺杂,能够细化电极表面的球形颗粒并提高电极表面粗糙度,从而提升电极的比表面积,为析氢反应提供更多的活性位点,利于析氢反应效率的提高。由于三元合金的协同作用,与二元合金Ni-Mo/NF相比,Ni-Mo-Nd/NF三元合金电极显示出更优异的HER催化性能。     

Ni/LaNi5多孔复合电极的制备及其析氢电催化性能

先电沉积Ni-Zn合金镀层,然后用浓碱将镀层中的锌脱溶,得到多孔镍,最后采用复合电沉积将LaNi5镶嵌到多孔镍表面,制备成Ni/LaNi5多孔复合电极。采用稳态极化曲线和交流阻抗谱对电极的电催化析氢性能进行了评价,并运用恒电位间歇电解和长时间电解,开路电位等研究了电极的电析氢稳定性。结果表明:Ni/LaNi5多孔复合电极的析氢表观交换电流密度分别是镍和多孔镍的172倍和26倍;多孔复合电极中的LaNi5具有稳定电极的作用,该电极比多孔镍具有更优异的抗断电性能。     

添加剂Pr2O3和Er2O3对电沉积Ni-S合金电极性能的影响

以氧化镨、氧化铒为添加剂,在泡沫镍基体上电沉积制备Ni-S镀层电极。对镀层的表面形貌、镀层结构、电沉积行为及镀层的电化学性能进行研究。结果表明：电镀液中添加稀土氧化物后电沉积过程的阴极极化增强,沉积层晶粒细化,比表面积增大,因而电极的析氢过电位降低;其中,添加Pr203的Ni-S镀层在250mA／cm2下碱性水电解时过电位降低达37mV,且该镀层电极在碱性介质下具有较高的析氢活性和耐腐蚀性能,在100h水电解实验中表现出较强的稳定性。     

柠檬酸钠对Ni-Sn-Mo合金电沉积机理及析氢行为的影响

目的 在酸性柠檬酸钠体系中,研究了柠檬酸钠对Ni-Sn-Mo合金电沉积机理的影响,明确最大电极反应速率和析氢性能最好的合金镀层对应的柠檬酸钠浓度。方法 采用循环伏安法、电化学阻抗谱、计时电流法和阴极极化曲线,对不同柠檬酸钠浓度下Ni-Sn-Mo合金电沉积行为及析氢性能进行研究,采用扫描电镜对Ni-Sn-Mo合金的表面形貌进行表征,并用能谱仪检测合金的成分。结果 由循环伏安曲线得出Ni-Sn-Mo合金的电沉积是一个不可逆过程,当柠檬酸钠浓度为0.2 mol/L时,合金共沉积还原峰的电位最正（-0.96 V(vs. Ag/Ag+)）。由电化学阻抗谱可知,当柠檬酸钠浓度为0.1 mol/L时,在低频端出现扩散特征;当柠檬酸钠浓度为0.2~0.4 mol/L时,反应不受扩散影响;当柠檬酸钠浓度为0.2 mol/L时,极化电阻（Rp）达到最小值（11 718.1 Ω?cm2）,电极反应最容易发生。由计时电流曲线可知,随着柠檬酸钠浓度的增大,Ni-Sn-Mo合金晶核形成始终遵循连续成核规律。由SEM和EDS分析表明,随着柠檬酸钠浓度增大,Ni-Sn-Mo合金的晶粒尺寸先减小后增大;随着合金中Sn含量增加,合金的晶粒由胞状转变为不规则形状。由阴极极化曲线和电化学阻抗谱可知,当柠檬酸钠浓度为0.1 mol/L时,析氢电位（-1.05 V）最正,电荷转移电阻（4.906 Ω?cm2）最小,析氢性能最好,从能量因素和几何因素上都改善了合金的析氢性能。结论 当柠檬酸钠浓度为0.2 mol/L时,还原峰电位最正,电极反应最容易发生。在Ni-Mo合金镀层中添加Sn,增加了镀层的比表面积,并且提高了电子传输速率,有利于析氢性能的提高。     

磺基水杨酸对镍硫合金涂层结构及电化学性能的影响

以硫脲为硫源、磺基水杨酸为改性剂,采用改进的Watt浴体系电沉积制备镍-硫合金涂层电极,用SEM观察涂层表面形貌,XRD分析涂层结构与相组成,电化学测试方法分析涂层的电化学行为.结果表明,磺基水杨酸在电沉积过程中既促进了晶核的形成,又阻碍了晶粒的长大,导致Ni-S沉积层的晶粒细化、非晶态化程度和硫含量的提高.所制备的Ni-S合金涂层具有较好的附着力,用于碱性水电解时有较高的析氢活性.当镀液中磺基水杨酸浓度为5 g/L时,Ni-S合金镀层附着力增大至19 MPa,析氢过电位降低约13 mV.     

Ni-La-P合金电镀及其析氢电催化性能研究

用正交实验研究了Ni-La-P电沉积的最佳工艺条件，以此合金作阴极测得析氢阴极极化曲线，结果表明，合金电极上析氢速率比Ni电极上约大10倍，析氢电势正移300～400mV，显示出含稀土La的镍基合金具有较高的析氢电催化活性。根据XPS谱图讨论了析氢电催化的机理。     

Ni-Cr-Cu三元合金电极制备及其析氢性能研究

以废旧紫铜片为基体,Ni粉、Cr粉为覆膜材料,通过活化反应烧结法制备了Ni-Cr-Cu三元合金电极材料。采用X射线衍射分析(XRD)、场发射电镜(SEM)、能谱(EDS)等对电极的物相、形貌结构、元素分布以及析氢产物进行表征;通过循环伏安、线性极化、交流阻抗等方法测试了合金电极材料的电催化析氢性能。结果表明,Ni-Cr-Cu三元合金薄膜电极具有优异的析氢性能,调节Cr元素的含量可提高其析氢催化活性,在室温条件下,Ni30%Cr-Cu三元合金电极材料在6 mol/L KOH的溶液中析氢性能较好,其析氢过电位仅有-0.13 V (vs RHE),交换电流密度为10 mA/cm~2时对应的极化电位为-0.145 V (vs RHE);经开路电位测试36 000 s后,电极材料的开路电位(η)从0.05 V变化为0.02 V,仅降低0.03 V,表明析氢电极化学稳定性良好。     

镍硫钴析氢电极的制备及性能研究

采用电沉积方法制备Ni-S-Co合金电极,通过正交实验和极化曲线测试研究了CoSO4·7H2O浓度、电流密度、电镀液温度、电沉积时间和电解液温度对Ni-S-Co电极析氢性能的影响.采用SEM,XRD和EDXA对镀层的形貌、结构和组成进行观察和分析.实验结果表明:制备具有最佳析氢活性的Ni-S-Co电极的工艺条件是25 ...     

脉冲电沉积纳米晶Ni-Co合金镀层腐蚀特性研究

采用X射线衍射(XRD)、扫描电镜(SEM)、能谱分析(EDS)等方法研究了脉冲电沉积法制各纳米晶Ni和纳米晶Ni-Co合金镀层的组织结构、表面形貌和成分.用浸泡法和电化学极化法研究了纳米晶Ni和不同Co含量的纳米晶Ni-C0合金镀层在3.5%NaCl(质量分数,下同)和5%HCl溶液中的腐蚀行为.结果表明:通过脉冲电沉积法制各的Ni和Ni-Co合金镀层具有典型的纳米晶结构; 随着含Co量的增加,镀层的晶粒尺寸减小,硬度增加;所制备的纳米晶Ni-Co合金镀层组织结构均匀致密,其在3.5%NaCl溶液和5%HCl溶液中的耐蚀性均优于纳米晶Ni镀层;纳米晶Ni-Co合金镀层在3.5%NaCl溶液的浸泡腐蚀中腐蚀极少,表现出优异的耐腐蚀性能,而在5%HCl溶液中的腐蚀形态则为均匀腐蚀.     

Electrochemical hydrogen absorbing properties of graphite/AB5 alloy composite electrode

Graphite is an inexpensive carbon material, but its hydrogen absorbing performance has attracted little attention. In this paper, in order to lower the cost of nickel metal-hydride (Ni-MH) battery, graphite is used as a hydrogen absorbing material in its negative electrode. The results of charge-discharge tests show that the graphite electrode has poor electrochemical hydrogen absorbing performance. The capacity of the graphite/AB₅ alloy (90 wt%) composite electrode is close to AB₅ alloy (298 mAh/g), but it has higher charge-discharge polarization and difficulty in activation. When graphite is modified with metal nickel powder by a simple ball milling process, the capacity of the composite electrode reaches to 315 mAh/g and its activation is accelerated. The results of electrochemical impedance spectroscopy (EIS) tests show that hydrogen diffusion in the modified composite electrode is more rapid than in AB₅ alloy, thereby resulting in lower charge-discharge polarization and better discharge performance at large currents.     

化学镀镍对A2B7型贮氢合金电极电化学性能的影响

本文对气态粉化后A2B7型贮氢合金La0.75Mg0.25Ni3.44Al0.06进行化学镀不同厚度Ni包覆处理.通过SEM观察,结果表明,包覆处理后镀层镍为球形颗粒且均匀弥散于合金表面.电化学测试结果表明,表面包覆镍处理的A2B7型合金电极放电容量有所降低,而循环稳定性有所提高.线性极化扫描和电化学阻抗谱等分析结果表明,表面包覆Ni处理后增大了合金电极的交换电流密度(I0),减小了电化学阻抗,改善了合金电极的动力学性能.     

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.     

Beneficial effects of Co2＋ on co-electrodeposited Ni-SiC nanocomposite coating

Ni-SiC nanocomposites were fabricated by co-electrodeposition of nickel with silicon carbide nanoparticles on the pure nickel substrates from a nickel sulfate bath with and without the addition of Co2+. The presence of Co2+ in the electrolyte modifies the Ni matrix to Ni-Co solid solution matrix. It helps to refine the grain size of the nanocomposite coating and improves the content of SiC dispersed in the matrix, and consequently results in higher microhardness. The cathodic polarization curves and electrochemical impedance spectroscopy (EIS) at cathodic potential were investigated in the electrolyte with and without Co2+. A modified cathodic polarization curve with a positive shift in reduction potential and a smaller capacitive loop of EIS are observed. These are attributed to the strong adsorption of Co2+ on the SiC nanoparticles. Consequently, it increases the forces of electrostatic attraction between the SiC nanoparticles and the cathode, which promotes the codeposition of SiC nanoparticles in the matrix.     

Studies of Structure and Electrocatalytic Hydrogen Evolution on Electrodeposited Nanocrystalline Ni-Mo Alloy Electrodes

Nanocrystalline Ni-Mo alloy deposits were obtained by electrodeposition. The structures of the alloy deposits were analyzed by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD shows that Ni-Mo alloy deposit with 15·2% molybdenum exhibits (111) preferred orientation, the lattice constant is larger than that of nickel metal. The XPS results on nanocrystalline Ni-Mo alloy deposits indicate that the nickel and molybdenum of the deposits exist in the metallic state, the binding energy of the alloyed elements increase to some extent. The nanocrystalline Ni-Mo alloy deposit electrode may offer better electrocatalytic activity than the polycrystalline nickel electrode. The electrochemical impedance spectra from the nanocrystalline Ni-Mo alloy electrode indicate that hydrogen evolution in 30% (m/m) KOH is in accordance with the Volmer-Heyrovsky mechanism.     

The electrochemical hydrogen storage of CNTs synthesized by CVD using LaNi5 alloy particles as catalyst and treated with different temperature in nitrogen

The multi-wall carbon nanotubes (MWNTs) were synthesized by chemical vapor deposition (CVD) using LaNi₅ alloy particles as catalyst. The effect of 40–60 nm MWNTs treated with different temperature in nitrogen on the electrochemical properties of CNTs–Ni electrode were investigated. Three-electrode system was introduced for testing electrochemical hydrogen storage of the electrode. The CNTs–Ni electrodes were used as the working electrode, which were prepared by mixing MWNTs and Ni powder in a weight ratio of 1:10 (MWNTs:Ni). Ni(OH)₂/NiOOH worked as the counter electrode and Hg/HgO as the reference electrode. A 6 mol/L KOH solution acted as the electrolyte. MWNTs treated with different temperature in nitrogen ambient represented a great discrepancy in the electrochemical hydrogen storage capability under the same testing condition. The CNTs–Ni electrodes with 40–60 nm diameter CNTs which were treated in a temperature of 800 °C in nitrogen has the best electrochemical hydrogen storage capacity of 588.1 mAh/g and a corresponding discharging plateau voltage of 1.18 V. From 500 to 800 °C, the higher temperature the MWNTs treated, the better the electrochemical hydrogen storage property of them is. This shows that the temperature of treatment is an important factor that influences electrochemical hydrogen storage performance of MWNTs.     

表面活性剂对铝合金表面电化学沉积硅烷膜层的影响

采用交流阻抗技术研究了表面活性剂对不同条件下双-1,2-[3(三乙氧基)硅丙基]四硫化物硅烷在铝合金表面阴极电化学辅助沉积成膜的影响.研究表明:在硅烷溶液中加入表面活性剂进行改性,可降低硅烷在铝合金表面电化学沉积的阴极沉积电位,抑制硅烷沉积过程中的析H2作用,改善电极界面区域硅烷成膜环境.试验证明:硅烷溶液中表面活性剂的最佳改性浓度为0.03%,在此浓度下,铝合金表面硅烷阴极电沉积的最佳沉积电位为-1.6V.