共查询到17条相似文献,搜索用时 62 毫秒
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采用循环伏安、方波伏安和开路计时电位等研究了Ho(Ⅲ)离子在LiCl-KCl共晶熔体中的电化学行为及Ho-Ni合金化机理。在惰性W电极上,Ho(Ⅲ)离子在-2.06 V(vs Ag/AgCl)发生电化学还原,该还原过程为3个电子转移的一步反应。与惰性W电极上的循环伏安相比,Ho(Ⅲ)离子在活性Ni电极的循环伏安曲线上还出现了3对氧化还原峰,是Ho与Ni形成了金属间化合物,导致了Ho(Ⅲ)离子在活性Ni电极发生了欠电位沉积。在不同的电位进行恒电位电解制备的3个不同的Ho-Ni合金,采用X-射线衍射(XRD)和扫描电子显微镜-能谱仪(SEM-EDS)等测试手段进行表征,结果表明:制备的3种合金分别是Ho2Ni17,HoNi5 和 HoNi2 3种合金化合物。 相似文献
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采用循环伏安、方波伏安和开路计时电位等电化学方法研究了Dy(Ⅲ)离子在LiCl-KCl 共晶盐中的电化学行为及Dy-Ni 合金形成的电化学机理. 循环伏安和方波伏安法研究表明, Dy(Ⅲ)离子的电化学还原过程为三个电子转移的一步反应. 与惰性W电极相比, Dy(Ⅲ) 离子在Ni 电极上的循环伏安曲线多出了三对氧化还原峰,是由于Dy与Ni 形成了合金化合物, 导致Dy(Ⅲ)离子在活性Ni 电极发生了欠电位沉积. 采用X射线衍射(XRD)和扫描电子显微镜(SEM)附带能量散射谱(EDS)对恒电位(-1.6, -1.8 和-2.0 V)电解制备的Dy-Ni 合金进行分析, 分别获得了DyNi5, Dy2Ni7和DyNi2金属间化合物. 实验结果表明, 通过控制电位进行恒电位电解可以有选择性地制备不同的金属间化合物. 相似文献
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采用循环伏安、方波伏安和开路计时电位等电化学方法研究了Dy(III)离子在LiCl-KCl共晶盐中的电化学行为及Dy-Ni合金形成的电化学机理.循环伏安和方波伏安法研究表明, Dy(III)离子的电化学还原过程为三个电子转移的一步反应.与惰性W电极相比, Dy(III)离子在Ni电极上的循环伏安曲线多出了三对氧化还原峰,是由于Dy与Ni形成了合金化合物,导致Dy(III)离子在活性Ni电极发生了欠电位沉积.采用X射线衍射(XRD)和扫描电子显微镜(SEM)附带能量散射谱(EDS)对恒电位(-1.6,-1.8和-2.0 V)电解制备的Dy-Ni合金进行分析,分别获得了DyNi5, Dy2Ni7和DyNi2金属间化合物.实验结果表明,通过控制电位进行恒电位电解可以有选择性地制备不同的金属间化合物. 相似文献
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采用循环伏安、方波伏安、计时电位和开路计时电位等电化学方法研究了Pr(Ⅲ)离子在共晶LiClKCl熔盐中Ni电极上的电化学行为及Pr-Ni合金化机理.结果表明,Pr(Ⅲ)离子的电化学还原过程为三电子转移的一步反应.与惰性Mo电极上的循环伏安曲线相比,Pr(Ⅲ)离子在活性Ni电极的循环伏安曲线上还出现了4对氧化还原峰,表明Pr(Ⅲ)离子在Ni电极上发生欠电位沉积,是由于生成不同的Pr-Ni金属间化合物.采用X射线衍射仪和扫描电子显微镜-能谱仪等对恒电位电解的产物进行了表征.结果表明,在不同电位下进行恒电位电解时,每个电位上只得到一种Pr-Ni金属间化合物,分别为Pr Ni2,Pr Ni3,Pr2Ni7和Pr Ni5. 相似文献
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采用循环伏安、 方波伏安、 计时电位和开路计时电位等电化学方法研究了Pr(Ⅲ)离子在共晶LiCl-KCl熔盐中Ni电极上的电化学行为及Pr-Ni合金化机理. 结果表明, Pr(Ⅲ)离子的电化学还原过程为三电子转移的一步反应. 与惰性Mo电极上的循环伏安曲线相比, Pr(Ⅲ) 离子在活性Ni电极的循环伏安曲线上还出现了4对氧化还原峰, 表明Pr(Ⅲ)离子在Ni电极上发生欠电位沉积, 是由于生成不同的Pr-Ni金属间化合物. 采用X射线衍射仪和扫描电子显微镜-能谱仪等对恒电位电解的产物进行了表征. 结果表明, 在不同电位下进行恒电位电解时, 每个电位上只得到一种Pr-Ni金属间化合物, 分别为PrNi2, PrNi3, Pr2Ni7和PrNi5. 相似文献
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采用循环伏安、方波伏安、计时电位和开路计时电位等电化学方法研究了Pr(Ⅲ)离子在LiCl-KCl-BiCl3熔体中W电极上的电化学行为。循环伏安和方波伏安的研究表明,Pr在预先沉积的Bi膜电极上发生欠电位沉积是由于生成了Pr-Bi金属间化合物,导致Pr(Ⅲ)在Bi膜电极上的还原电位比在W电极上还原电位更正。从开路计时电位曲线可以观察到两相共存的Pr-Bi金属间化合物的两个平台。利用开路计时电位计算了723-873 K温度范围内Pr在Pr-Bi合金中的活度和偏摩尔Gibbs自由能以及Pr-Bi金属间化合物的生成Gibbs自由能。通过恒电位电解,在液态Bi电极上得到了Pr-Bi合金,并采用X射线衍射(XRD)和扫描电子显微镜(SEM)附带能量散射谱(EDS)对样品进行了表征,结果表明所得到的Pr-Bi金属间化合物为PrBi2和PrBi。 相似文献
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讨论了钌(Ⅱ)聚吡啶化合物[Ru(bipy)2dppz]2+(bipy=2,2-联吡啶;dppz=吡啶并[3,2-a2′,3′-c]吩嗪)的电化学行为.在盐酸溶液中,化合物在-0.11 V和-0.08 V (vs.SCE)出现一对峰,它在玻碳电极和碳糊电极上均表现出吸附特性.在玻碳电极上的最大吸附量Γmax为2.37×10-11 mol/cm2,吸附系数β0为4.89×105 L/mol,在电极上的吸附行为符合Langmuir吸附等温式.实验中发现该化合物能对亚硝酸根的还原起催化作用. 相似文献
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Electrochemical intercalation of lithium into intermetallic compounds (IMC) MgCd and MgCd3 out of propylene carbonate solutions of LiBF4 is studied. According to chronopotentiometry data, during the intercalation, lithium forms compounds with cadmium: Li3Cd on MgCd or LiCd and Li3Cd on MgCd3. Reactions of solid-phase substitution, which occur on the electrodes, are accompanied by the destruction of initial IMC and generation of magnesium atoms. Chronoamperometry of MgCd–(Li) and MgCd3–(Li) shows the lithium intercalation to be limited by nonstationary diffusion of lithium in the solid phase. The lithium diffusion in MgCd is slower and that in MgCd3is faster than in Cd. The calculated potential dependences of the diffusion coefficient for lithium in MgCd and MgCd3 are linear in semilogarithmic coordinates. 相似文献
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The electrochemical properties of CeCl3, dissolved in LiCI-KCI eutectic melt, were investigated by electrochemical techniques, such as cyclic voltammetry and square wave voltammetry on Mo electrode. It was shown that Ce(Ⅲ) is reduced to Ce(0) based on a three-step mechanism. In a temperature range of 833-923 K, the diffusion coefficient of Ce(Ⅲ) is lgDceoH)=-2.49-1704/T determined by means of the Berzins-Delahay equation with two different expressions under reversible and irreversible conditions. The apparent standard potential of a Ce(Ⅲ)/Ce(0) redox system is ECE^3+0^*/Ce^0 =3.551+0.0006132T(K) vs. Cl2/Cl^-. Some thermochemical properties of CeCl3 solutions were also derived from the electrochemical measurements, such as the enthalpy, entropy, Gibbs free energies and the activity coefficients of Ce(Ⅲ). The Gibbs free energy of a dilute solution of CeCl3 in this system was determined to be △G^0CeCl3/(kJ·mol^-1)=-1027.9+0.178T(K) And the activity coefficients, γCeCl3 , range between (7.78-9.14)×10^-3. Furthermore, the standard rate constant of kinetic reaction was calculated to be (4.94-9.72)× 10^-3 cmZ/s and the reaction was regarded as a quasi-reversible reaction under the present experimental conditions at 833 K. 相似文献
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在803 K LiCl-KCl熔盐中, 研究了通过添加助剂AlCl3直接电化学还原Sm2O3和Al-Sm合金的形成。以SmCl3为原料作为参照, 采用循环伏安和方波伏安方法, 研究了Sm2O3在LiCl-KCl-AlCl3熔盐体系中的电化学行为。通过对比发现在两个体系中, 峰的数量和位置基本一致, 这说明在LiCl-KCl熔盐中, 加入AlCl3之后, 可以将Sm2O3有效氯化。计时电位结果表明, 当阴极电流比-139.8 mA·cm-2更负时, Al和Sm共同还原。为了提取Sm, 采用恒电流从LiCl-KCl-AlCl3-Sm2O3熔盐中电解得到Al-Sm合金样品, 并进行XRD表征, 结果表明可以通过调节AlCl3和Sm2O3的浓度得到不同相的Al-Sm合金。 相似文献
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在803 K LiCl-KCl熔盐中,研究了通过添加助剂AlCl3直接电化学还原Sm2O3和Al-Sm合金的形成。以SmCl3为原料作为参照,采用循环伏安和方波伏安方法,研究了Sm2O3在LiCl-KCl-AlCl3熔盐体系中的电化学行为。通过对比发现在两个体系中,峰的数量和位置基本一致,这说明在LiCl-KCl熔盐中,加入AlCl3之后,可以将Sm2O3有效氯化。计时电位结果表明,当阴极电流比-139.8 mA.cm-2更负时,Al和Sm共同还原。为了提取Sm,采用恒电流从LiCl-KCl-AlCl3-Sm2O3熔盐中电解得到Al-Sm合金样品,并进行XRD表征,结果表明可以通过调节AlCl3和Sm2O3的浓度得到不同相的Al-Sm合金。 相似文献
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研究了温度范围在723-908 K的LiCl-KCl 熔盐体系中MgCl2的电化学行为和热力学性质. 循环伏安和方波伏安法研究表明镁离子的电化学还原过程为包含了两个电子转移的一步反应. 利用Berzins 和Delahay 方程计算了不同温度下的镁离子的扩散系数, 并通过Arrhenius 公式计算了镁离子在LiCl-KCl 熔盐体系中的扩散活化能. 采用开路计时电位法得到了不同温度下的Mg(II)/Mg(0)体系的平衡电位, 并结合电动势法计算了在LiCl-KCl 熔盐体系中Mg(II)/Mg(0)体系的标准形式电位. 根据不同温度下的标准形式电位, 计算得到了MgCl2在LiCl-KCl 熔盐体系中的熵变和焓变以及不同温度下的活度系数. 相似文献
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Nicolas Köwitsch Stefan Barth Dr. Kevin Ploner Dr. Raoul Blume Dr. Detre Teschner Dr. Simon Penner Prof. Dr. Marc Armbrüster 《Chemphyschem》2022,23(8):e202200074
Heterogeneous catalysts are often complex materials containing different compounds. While this can lead to highly beneficial interfaces, it is difficult to identify the role of single components. In methanol steam reforming (MSR), the interplay between intermetallic compounds, supporting oxides and redox reactions leads to highly active and CO2-selective materials. Herein, the intrinsic catalytic properties of unsupported In3Pt2, In2Pt, and In7Pt3 as model systems for Pt/In2O3-based catalytic materials in MSR are addressed. In2Pt was identified as the essential compound responsible for the reported excellent CO2-selectivity of 99.5 % at 300 °C in supported systems, showing a CO2-selectivity above 99 % even at 400 °C. Additionally, the partial oxidation of In7Pt3 revealed that too much In2O3 is detrimental for the catalytic properties. The study highlights the crucial role of intermetallic In−Pt compounds in Pt/In2O3 materials with excellent CO2-selectivity. 相似文献
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Material development requires in many cases information about the necessary stability of the materials against oxidation, which is encoded in the chemical activity of the constituting elements. Determination of the chemical activity is tedious, especially for metallic materials at or close to ambient temperature. To determine the chemical activity of Zn at ambient temperature, electromotive force (EMF) measurements on the intermetallic compounds ZnPd, ZnPt and Cu5Zn8 within their respective homogeneity range were conducted. The single-phase nature of the samples was confirmed by powder X-ray diffraction, light microscopy as well as SEM/EDX analysis. To exclude oxidation, and therefore faulty determination of the electrochemical potentials, a method was developed to conduct the electrochemical measurements under non-corrosive conditions in inert atmosphere. Corrosion by the electrolyte was avoided using anhydrous dimethylformamide as aprotic solvent. From the EMF the respective intrinsic activities of zinc in the corresponding intermetallic compounds was determined. Measurements on Cu5Zn8 and comparison to available data in literature verified the developed method allowing to retrieve thermodynamic data of ZnPd and ZnPt for the first time at ambient temperature. The herein developed and easy-to-use methodology is applicable to a wide range of metallic material by choosing appropriate compositions of the electrolyte and has the potential to boost material development. 相似文献