稀土铈对镍-钴-磷合金电极的析氢催化性能的影响

采用自行研制的复合配合剂,用化学沉积法在酸性体系中制备了Ni-Co-P和Ni-Co-P稀土合金电极.研究了稀土元素铈对Ni-Co-P合金电极的析氢电催化活性和电化学稳定性的影响.通过电化学方法测定合金电极在7 mol/L KOH溶液中的阴极极化曲线、Tafel曲线和电化学稳定性曲线,结果表明,与Ni-Co-P合金电极相比,Ni-Co-P(RE)合金电极的析氢电位正移约90 mV,Ni-Co-P(RE)合金电极具有较优的析氢电催化活性和电化学稳定性.此外,还通过X射线衍射、扫描电镜和合金镀层成分分析,结果表明,稀土元素铈的加入使非晶态Ni-Co-P合金镀层晶粒细化,但稀土元素铈不与合金共沉积,只是起到改变镀层组织结构的作用.     

Electrochemical properties of amorphous Ni-S-Co alloy in alkaline medium

用电沉积方法制备非晶态Ni-S-Co合金镀层, 研究了镀层的电化学性能. 结果表明,与非晶态Ni--S合金相比, Co的引入可提高镀层中S的含量.在析氢反应中非晶态Ni--S--Co合金电极具有很高的电化学活性,电流密度为150 mA×cm-2时其析氢过电位仅为70 mV,比非晶态Ni-S合金低20 mV.在长时间电解过程中S发生溶出反应有助于提高电极的表面粗糙程度, 是提高电极析氢活性的重要原因之一. 在析氢过程中,非晶态Ni--S--Co合金电极吸附大量的H原子, 使反应的活化能降低,这是其析氢活性高的主要原因. 非晶态Ni--S--Co合金镀层的析氢机理为电化学脱附机理,即一快速的Volmer反应(电化学步骤)和一较慢的Heyrovsky反应(电化学脱附步骤).     

非晶态Ni-S-Co合金的制备和电化学性能

用电沉积方法制备非晶态Ni-S-Co合金镀层,研究了镀层的电化学性能.结果表明,与非晶态Ni-S合金相比,Co的引入可提高镀层中S的含量.在析氢反应中非晶态Ni-S-Co合金电极具有很高的电化学活性,电流密度为150 mA·cm-2时其析氢过电位仅为70 mV,比非晶态Ni-S合金低20 mV.在长时间电解过程中S发生溶出反应有助于提高电极的表面粗糙程度,是提高电极析氢活性的重要原因之一.在析氢过程中,非晶态Ni-S-Co合金电极吸附大量的H原子,使反应的活化能降低,这是其析氢活性高的主要原因.非晶态Ni-S-Co合金镀层的析氢机理为电化学脱附机理,即-快速的Volmer反应(电化学步骤)和一较慢的Heyrovsky反应(电化学脱附步骤).     

水溶液电沉积稀土合金膜的结构和性能研究

综述了水溶液中电沉积稀土合金膜的结构与性能的研究现状.其中结构包括显微结构、非晶形成规律、晶化动力学;性能涉及磁性、析氢电催化行为、耐腐蚀性、力学性能及光学性能.水溶液中电沉积稀土合金膜在一定的制备条件下具有非晶态结构,由于其优异的磁学、析氢电催化、耐腐蚀、力学及光吸收性能,已经应用于镀覆大的非平面电子装置、磁泡记忆元件、高温超导薄膜、磁光记录材料、电极材料、发光材料、储氢材料以及表面工程技术等领域,同时对水溶液中电沉积稀土合金膜的研究进行了展望.     

氯化胆碱-尿素体系中电沉积Ni-Fe-Sm析氢催化电极研究

采用恒电位电沉积技术,在氯化胆碱-尿素体系中制备Ni-Fe-Sm/Cu稀土合金电极并研究其析氢(HER)性能。通过阴极极化曲线(LSV)、循环伏安曲线(CV)等电化学测试方法及SEM等表征技术,研究沉积条件对稀土合金电极的析氢性能及其表面形貌的影响。结果表明,添加稀土元素Sm能够有效提升合金电极的析氢性能。在-1.22 V的沉积电位下,沉积20 min制备的Ni-Fe-Sm/Cu稀土合金电极析氢性能最佳。在10 mA/cm²电流密度下,稀土合金电极的析氢过电位仅115 mV,Tafel斜率最小,析氢反应受Volmer-Heyrovsky反应控制。且该条件下制备的Ni-Fe-Sm/Cu稀土合金具备最高的双电层电容,电催化活性表面积最大。通过交流阻抗法(EIS)可知,Ni-Fe-Sm/Cu合金电极具有较高电荷转移速率。此外,Ni-Fe-Sm/Cu稀土合金电极在碱性介质中具有较好的稳定性,在经过1000圈的循环侧安测试,电催化析氢性能没有明显变化。     

电沉积非晶态Co-W合金镀层在碱性溶液中的电催化析氢研究

利用恒电流直流电沉积方法在Cu基底表面制备了Co-W合金镀层,当镀液中WO_4~(2-)浓度≥0.075 mol/L时镀层为非晶态结构。电化学研究表明,非晶态Co-W合金镀层在1 mol/L NaOH溶液中表现出良好的电催化析氢活性,过程受Volmer-Heyrovsky路径控制。W含量约为40.1%(质量分数)的Co-W合金镀层析氢活性最强,其表观交换电流密度j_0为3.17×10~(-5)A/cm~2;当电位负于-1.464 V(相对于饱和甘汞电极电位)后该Co-W合金镀层的阴极电流密度超越了商用Pt片。结合电化学阻抗分析获知,由于镀层本征催化活性和比表面积(或电化学活性面积)均得到提升,使得非晶态Co-W合金镀层析氢活性获得提高。     

非晶态MmNi5.20合金薄膜的制备及析氢反应电催化性能的研究

用离子束溅射法制备非晶态ＭｍＮｉ＿（５．２０）合金薄膜。该非晶态合金薄膜在３０ｗｔ％ＫＯＨ，７０℃作析氢反应电极。实验结果表明，该电极不但具有良好的析氢电催化活性和电化学稳定性，而且具有很好的抗氢脆和抗粉化能力。交流阻抗分析表明，非晶态ＭｍＮｉ＿（５．２０）合金电极析氢反应过程主要由电化学反应步骤控制。     

非晶态合金催化析氢阴极材料的研究进展

非晶态合金由于其优异的物理化学性能而备受研究者重视.特殊的空间结构使其表现出良好的化学活性,利用其亚稳态特性赋予电极材料特殊的化学性能,可将非晶态合金用于析氢电极材料.综述了非晶态合金阴极材料的研究进展,对过渡族金属元素的特性进行了分析,指出由过渡族金属元素组成的、具有低析氢超电势和低成本的非晶态合金复合镀层是目前与今后研究催化析氢电极材料的主要方向.     

化学镀Ni-Co-W-P及其析氢性能的研究

用化学镀方法制备出Ni-Co-W-P合金电极,测量了其在1 mol/L NaOH溶液中的阴极极化曲线并研究了其析氢电催化活性.试验表明,在相同的电流密度下,Ni-Co-P,Ni-W-P和Ni-Co-W-P合金电极的析氢过电位较Fe电极降低,其中Ni-Co-W-P的析氢过电位降低约230 mV,XRD试验显示其镀层为非晶态.并进一步测试了其在7 mol/L KOH中的连续电解曲线.结果表明:Ni-Co-W-P合金电极比Ni-Co-P,Ni-W-P合金电极具有更好的析氢电催化活性和电化学稳定性,有利于降低槽压,减少能耗.     

稀土铈对镍-钴合金电极的析氢催化性能的影响

采用电沉积方法制备了Ni—Co和Ni—Co(RE)合金电权。通过电化学方法研究了其在7mol/L KOH溶波中的析氢电催化活性。实验发现，与Fe电权相比，Ni—Co和Ni—Co(RE)合金电权的析氢电位正移，其中Ni—Co(RE)合金电权的析氢电位正移250mV。通过扫描电镜和合金镀层成分分析，探讨了稀土饰对Ni—Co合金电权析氢电催化性能的影响。结果表明，稀土饰的加入提高了合金电权在7mol/L KOH溶液中的析氢电催化活性和电化学稳定性。有利于降低槽压，减少能耗。     

Alloying (In,Mn)As and (Ga,Mn)As: Ferromagnetic (In,Ga,Mn)As Lattice-Matched to InP

An effect of alloying two ferromagnetic semiconductors (In,Mn)As and (Ga,Mn)As on the ferromagnetic properties of resultant (In,Ga,Mn)As alloys is reported. For conditions close to lattice-matching to InP substrates, y = 0.53 in (In _y Ga_1–y )_1–x Mn _x As, ferromagnetism up to Curie temperatures T _C = 100–110 K could be achieved for a Mn composition x = 0.13. Trends in the Curie temperature in (In,Ga,Mn)As are compared with (Ga,Mn)As and (In,Mn)As as a function of Mn content. Hole concentrations determined from magnetotransport, taking into account the anomalous Hall contribution to Hall resistance, gives p/Mn = 0.03 ratio to Mn composition in metallic case for x = 0.13. We mention the possible role of chemical ordering (short range) of Mn impurity atoms on hole concentration and, consequently, for the ferromagnetic properties.     

镨含量对（La,Pr,Nd）Ni3.5Co0.8Mn0.4Al0.3合金电化学性能的影响

目前广泛采用的镍－金属氢化物电池负极材料多为ＬａＮｉ５基合金。本实验研究了稀土中镨含量分别为０、１０％、２０％、３０％、４０％和５种（Ｌａ，Ｐｒ，Ｎｄ）Ｎｉ３．５Ｃｏ０．８Ｍｎ０．４Ａｌ０．３合金的电极性能。发现稀土中镨含是来２０％和３０％的合金比其它成分手合金具有更高的放电容量，更好的电极稳定性。选用镨含量为１７％的富镧混合稀土制备了成分为ＭｌＮｉ３．５Ｃｏ０．８Ｍｎ０．４Ａｌ０．３的电极合金，     

复合氧化物Ln0.67Sr0.33MnO3（Ln=La,Pr,Nd,Sm）的制备,结构与电性

本语文通过共沉淀工艺合成了复合氧化物Ｌｎ０．６７Ｓｒ０．３３ＭｎＯ３（Ｌｎ＝Ｌａ、Ｐｒ、Ｎｄ、Ｓｍ）与传统陶瓷制备方法相比，成相温度降低约４５０℃，经Ｘ射线衍射分析表明，所得复合氧化物为立方钙钛矿结构，晶胞参数随稀土离子半径变化而呈规律性变化，样品的四极法电阻率测试结果表明；样品中的稀土离子Ｌｎ的离子半径对其本身的地电性起决定性的作用，应用双交换理论，样品中的稀土离子Ｌｎ的离子半径对其本身的导电性     

Study of (Zr,Ti)CN, (Zr,Hf)CN and (Zr,Nb)CN films prepared by reactive magnetron sputtering

(Zr,Ti)CN, (Zr,Hf)CN and (Zr,Nb)CN coatings, in which Ti, Hf and Nb were added to ZrCN base compound, have been prepared by reactive magnetron sputtering. The coatings, with two different non-metal/metal ratios, were comparatively investigated in terms of elemental and phase composition, texture, surface morphology, hardness and friction performance. It has been shown that the films exhibit nanocomposite structures, consisting of a mixture of crystalline metal carbonitride and amorphous carbon. As compared with ternary ZrCN coatings, the quaternary coatings were found to exhibit superior mechanical and friction characteristics. In general, the films with higher non-metal content revealed finer morphologies, higher hardness and lower friction coefficient. Depending on the coating type and non-metal/metal ratio, the hardness values ranged from about 21 to 29 GPa, being higher than those of ZrCN reference films. The coefficients of friction varied from 0.2 to 0.5, the lowest values being obtained for the coatings with the highest non-metal content.     

Hydrogenation of the Laves Phases of Gd(Mn,Al)2, Tb(Mn,Al)2, and Tb(Fe,Al)2 Compounds

We study the formation of the AB₂ Laves phases in RE–M–Al (where RE is Gd or Tb and M is Fe or Mn) systems and determine their hydrogen-sorption properties. The crystal structures of the original compounds and their saturated hydrides are studied by the X-ray powder diffraction method. It is shown that these compounds absorb hydrogen at pressures of 0.1–0.12 MPa without amorphization and their hydrogen-sorption ability decreases as the amount of aluminum in the compound increases.     

Sol-Gel Processing of Zr(C,N,O) and Al(C,N,O) Powders

,-Diaminoparaxylene was reacted with Zr(OPr ⁿ )₄ at a molar ratio r = 2 or with Al(OBu ^s )₃ with a molar ratio r = 1.5 or 2. Characterization of the obtained hybrid organic–inorganic gels by FTIR, XRD, TGA, and ¹³C CP-MAS NMR showed that a substitution reaction occurred between the OPr ⁿ or OBu ^s groups of the alkoxides and the HN—CH₂—C₆H₄—CH₂—NH groups of the diamine. Powders derived from hybrid gels pyrolysis were also analyzed.     

Synthesis,Electrical Conductivity and Seebeck Coefficient of La_(0.9)A_(0.1)FeO_3(A=Mg,Ca,Sr,Ba)

Lanthanum ferrites ceramics La0.9A0.1FeO3(A=Mg,Ca,Sr,Ba) have been prepared by solid state reaction.X-ray power diffraction analysis reveals that all samples are of pure perovskite structure with orthorhombic phase.Electrical conductivity and Seebeck coefficient have been measured in vacuum within the temperature range between room temperature and 800℃.The electrical conductivity shows semiconducting behavior.Temperature dependence of electrical conductivity indicates that adiabatic small-polaron hopping me...     

Study of the R-(Zr,W)-(O,N) (R = Y, Nd, Sm, Gd, Yb) oxynitride system

The replacement of tantalum by the couple Zr/W within the RTa-O-N systems (R = Y, Nd, Sm, Gd, Yb), enables the preparation of novel oxide and oxynitride phases in the R-Zr-W-O-N system. R₂Zr_2−xW_xO_7+x oxides exhibit the fluorite-type (x < 0.9) and scheelite (x ∼ 1) structures. Corresponding oxynitride compositions are of the fluorite-type and show different colors, for example in the case of ytterbium: pale yellow (x = 0.2 or 0.25), green (x = 0.5-0.8) and brown for the tungsten-rich samples (x = 0.9, 1). Photocatalytic activity measurements have been performed to investigate the overall water splitting behavior of these colored phases.