Anodic dissolution of magnetic layers based on cobalt and nickel in conditions of electrodeposition of multilayered nanostructures by a single-bath method

Methods of quartz microgravimetry (in solutions containing no copper ions) and stripping voltammetry (in copper-containing solutions) are used to study the process of anodic dissolution of thin deposits of pure Co and Ni and deposits of these metals with inclusion of copper in the potential region of copper deposition. It is shown that, under these conditions, Ni practically does not dissolve in either the sulfate or chloride-containing electrolytes, whereas Co dissolves in sulfate electrolytes at a rate that is dependent on the potential and increases with its shift into the positive region. Stability of ternary CoNiCu deposits is examined and it is demonstrated that additionally inserting Ni in the composition of a magnetic CoCu layer facilitates suppression of selective dissolution of Co.     

Composition of magnetic layer and magnetotransport properties of electrodeposited layered nanostructures (Co-Cu)/Cu and (Ni-Co-Cu)/Cu

The magnetotransport characteristics of Co-Ni-Cu layered coatings containings 100 nanobilayers were measured at room temperature in a magnetic field of ±5 kOe. The coatings were deposited onto nickel sputtered on glass. It is shown that a decrease in the content of copper in the magnetic layer due to the conversion of copper ions in the solution into the multi-charge anionic complexes (by the example of sulfosalicylate electrolyte) leads to an increase in the giant magnetoresistance (GMR) effect. The stabilization of composition of Co-based magnetic layer by shifting the copper deposition potential to the equilibrium potential of Co or by introducing Ni, which assists the deposit passivation, leads to a decrease of the GMR effect. A benefit effect of partial dissolution of Co at the deposition potentials of nonmagnetic layer on the magnetotransport characteristics of multilayered coatings is first revealed. It is supposed that the effect is caused by the morphological factor of surface smoothing due to preferential dissolution of projecting areas of magnetic layer.     

Synthesis, crystal structures and magnetic properties of M(II)Cu(II) chains (M = Mn and Co) with sterically hindered alkyl-substituted phenyloxamate bridging ligands

A series of neutral oxamato‐bridged heterobimetallic chains of general formula [MCu(L^x)₂(S)₂] ? p S ? q H₂O [p=0–1, q=0–2.5; L¹=N‐2,6‐dimethylphenyloxamate, S=DMF with M=Mn ( 1 a ) and Co ( 1 b ); L²=N‐2,6‐diethylphenyloxamate, S=DMF with M=Mn ( 2 a ) and Co ( 2 b ) or S=DMSO with M=Mn ( 2 c ) and Co ( 2 d ); L³=N‐2,6‐diisopropylphenyloxamate, S=DMF with M=Mn ( 3 a ) and Co ( 3 b ) or S=DMSO with M=Mn ( 3 c ) and Co ( 3 d )] were prepared by treating the corresponding anionic oxamatocopper(II) complexes [Cu(L^x)₂]^2? (x=1–3) with M²⁺ cations (M=Mn and Co) in DMF or DMSO as the solvent. The single‐crystal X‐ray structures of 2 a and 3 a reveal the occurrence of well‐isolated, zigzag, oxamato‐bridged manganese(II)–copper(II) chains. The intrachain Cu ??? Mn distances across the oxamato bridge are 5.3761(7) and 5.4002(17) Å for 2 a and 3 a , respectively, whereas the shortest interchain Mn ??? Mn distances are 9.4475(16) and 8.1649(14) Å for 2 a and 3 a , respectively. All of these M^IICu^II chains (M=Mn and Co) exhibit 1D ferrimagnetic behaviour with moderately strong intrachain antiferromagnetic coupling between the square‐planar Cu^II and octahedral high‐spin M^II ions across the oxamato bridge [?J=31.4–35.2 and 33.4–44.8 cm^?1, respectively; H =∑_i?J S _M,i( S _Cu,i+ S _Cu,i?1)]. Only the Co^IICu^II chains show slow magnetic relaxation effects characteristic of single‐chain magnets (SCMs). Analysis of the magnetic relaxation dynamics of 3 d shows a thermally activated mechanism (Arrhenius law dependence) with values of the pre‐exponential factor (τ₀=2.6×10^?9 s) and activation energy (E_a=7.7 cm^?1) that are typical of SCMs. In contrast, two relaxation regimes are observed for 2 d in different temperature regions (τ₀=3.2×10^?10 s and E_a=24.7 cm^?1 for T<4.5 K and τ₀=3.2×10^?14 s and E_a=37.5 cm^?1 for T>4.5 K).     

Synthesis and neel temperature determination of ferrites from the MO−ZnO−Fe2O3 systems (M=Cu,Co and Ni)

The Curie (Neel) temperature is successfully determined by means of a simple magnetic device attached to the Q Derivatograph (MOM, Hungary), which is widely used in many laboratories. This possibility is demonstrated by a study of ferrite materials with general formula M_xZn_1?xFe₂O₄ (M=Cu, Co and Ni;x=0.0; 0.2; 0.4; 0.5; 0.6; 0.8; 1.0). X-ray phase analysis, Mössbauer spectroscopy and microscopic examinations revealed that the obtained ferrites are monophase samples. The mixed ferrites possess more strongly expressed magnetic properties than those of the individual ferrites; the maximum magnetic interaction in these ferrites is observed at different zinc contents.     

Cu含量对Cu/Al-Ce-PILC上丙烯选择性催化还原NO反应的影响

 采用聚合羟基复合阳离子合成交联粘土Al-Ce-PILC,经SO2-4改性后,以浸渍法制备了用于C3H6选择性还原NO反应的铜基交联粘土催化剂Cu/Al-Ce-PILC. 用XRD,XPS和TPR等技术对催化剂进行了表征,并考察了Cu含量对催化剂性能的影响. 结果表明,Cu负载未改变Al-Ce-PILC的结构; w(Cu)=2%时,Cu物种以Cu+和Cu2+两种形式存在,催化剂具有最高的催化活性和较宽的操作温度范围,在反应气组成为0.22%NO-0.12%C3H6-2.0%O2-97.66%He,空速为 24000 h-1和温度为350 ℃的条件下,NO转化率可达56.4%,700 ℃下仍可达22.3%; w(Cu)=5%时,催化剂中有明显的CuO物相存在,该物相促进C3H6的深度氧化,从而降低了NO选择性还原反应的性能.     

La2O3对Ni-Cu/MgSiO催化剂的甲烷部分氧化制氢反应性能的影响

 用等体积浸渍法制备了MgO-SiO2(MgSiO)复合氧化物负载的Ni-Cu双金属催化剂,采用程序升温还原(TPR),X光电子能谱(XPS),红外光谱(IR),程序升温脱附(TPD)及微反技术考察了稀土La2O3的加入对CH4和H2O在Ni-Cu/MgSiO催化剂表面上的吸附及甲烷部分氧化制氢反应性能的影响. 结果表明,加入La2O3使催化剂表面Ni和Cu原子的电子云密度增加,CH4和H2O在催化剂表面上的吸附增强. CH4与O2和H2O在Ni-Cu/MgSiO催化剂上反应的主要产物为H2和CO2. La2O3的加入有利于提高CH4转化率及H2的选择性,并可提高催化剂稳定性及抗积炭能力. 讨论了La2O3的助催化作用机理.     

焙烧温度对合成低碳醇用Cu/Mn/Ni/ZrO2催化剂性能的影响

 研究了焙烧温度对合成低碳醇用Cu／Mn／Ni／ZrO2催化剂结构及催化性能的影响．随着焙烧温度的升高，催化剂的催化活性和产物分布都发生较大的变化．催化剂在较低的温度下焙烧，低温下反应液相产物的分布符合S－F方程；反应温度升高时，液相产物中主要是甲醇和异丁醇；在高温下焙烧的催化剂，其催化活性较低，但即使在较低的反应温度下，异丁醇在液相高级醇（C2＋OH）中也是主要的产物．结合其他的一些反应结果与XRD，BET，TPR及EXAFS等表征结果，认为焙烧温度使催化剂的结构发生了较大的变化，进而影响催化剂各组分之间的相互作用，从而使催化剂对合成低碳醇反应表现出不同的催化性能．     

迭代目标转换因子分析光度法用于铜锌钴镍锰同时测定的研究

本运用迭代目标转换因子分析光度法，在ｐＨ９的介质条件下，以５－Ｂｒ－ＰＡＤＡＰ－０Ｐ体系，对Ｃｕ，Ｚｎ，Ｎｉ，Ｍｎ五组分的合成试样及地质标样进行了分析测定。结果表明，各组份的相对误差一般都小于１０５，最低检测限为３．８×１０＾－＾９－５．２×１０＾－＾９，获得满意结果。该算法避免了一般因子分析法中对转换矩阵求逆的运算工程，降低了实验误差在计算过程中被放大的可能性，从而提高了对浓度计算的准确度。     

Reactivity and transformation routes of surface nitrates in the reaction of NOx reduction by C3H8 over cation-exchanged zeolites

FITRS combined with¹⁵N and¹⁸O isotope substitution and TPD have revealed that nitrates are the most abundant ad-NO_x species on over-exchanged Cu- and Co-ZSM-5 zeolites. the transformation rates of such species under the action of a propane—oxygen mixture were found to be comparable and sufficiently high to afford steady-state catalytic activities. A scheme of the reaction mechanism including C, N-containing intermediates detected in work is suggested.     

Synchronous Electrocatalytic Design of Architectural and Electronic Structure Based on Bifunctional LDH-Co3O4/NF toward Water Splitting

The rational design of highly efficient bifunctional electrocatalysts for water splitting is extremely urgent for application in sustainable energy conversion processes to alleviate the energy crisis and environmental pollution. In this work, through simple deposition of layered double hydroxides (LDH) on Co₃O₄/NF (NF=nickel foam) nanosheets arrays, hierarchical Co³⁺-rich materials based on LDH-Co₃O₄/NF are prepared as highly active and stable electrocatalysts for water splitting. The NiFe-LDH-Co₃O₄/NF demonstrates excellent electrochemical activity with an overpotential of 214 mV for the OER and an overpotential of 162 mV for the HER at 10 mA cm⁻². Such a performance is attributed to the optimized electronic states with a high concentration of Co³⁺, which improves the intrinsic activity, and the sheet-on-sheet hierarchical structure, which increases the number of active sites. The unique synchronous design of both the architectural and electronic structure of nanomaterials can simultaneously accelerate the reaction kinetics and provide a more convenient charge transfer path. Therefore, the strategy reported herein may open a new pathway for the design of excellent electrocatalysts for water splitting.     

Influence of the composition on the electronegativity and on the oxygen charge distribution in a binary hydrotalcite-like by modified Sanderson method

An intuitive and computationally non-intensive model for the classification of Hydrotalcite-like compounds (HTLCs) based simply on the chemical composition using the Sanderson Method led to good prediction of basicity and different basic sites (oxygen atoms with different charge). That model was evaluated at different M³⁺ /(M²⁺+M³⁺) ratio and with different divalent and trivalent metallic cations.AMS subject classification: 92E10     

稀土Sm对于Cu/Zr基合成醇催化剂的改性作用

 采用BET,XRD,TPR,H2－TPD和NH3－TPD等表征手段,考察了稀土助剂Sm2O3的添加方式对Cu／Mn／Zr／Ni催化剂结构的影响,并与催化剂催化CO加氢合成醇反应的活性及选择性相关联．结果表明,加入稀土助剂后,催化剂的表面酸性明显增强,催化性能发生了很大变化,副产物烃和CO2的含量明显降低;反应过程中有大量二甲醚生成．此外,稀土助剂Sm2O3对催化剂有一定的电子改性作用,改变了催化剂表面的吸附行为．     

同一体系中铜(Ⅱ)、铅(Ⅱ)、镉(Ⅱ)、镍(Ⅱ)和钴(Ⅱ)的络合物吸附波及其分析应用

研究了丁二酮肟 氨 氯化铵 柠檬酸钠 明胶 抗坏血酸体系中Cu(Ⅱ )、Pb(Ⅱ )、Cd(Ⅱ )、Ni(Ⅱ )和Co(Ⅱ )的络合物吸附波 ,建立了同时测定水溶液中痕量相应元素的新方法。上述金属络合物分别在 -0 .44、-0 60、-0 .76、-1.0 7和 -1.2 4V左右产生灵敏的极谱波。信噪比为 3时 ,检出限分别为 1.0× 10 - 8、2 .3×10 - 8、1.3× 10 - 8、2 .9× 10 - 1 0 和 3 .6× 10 - 1 1 mol/L。铜、铅、镉、镍和钴的浓度分别为 2 .0× 10 - 8～ 2 .0× 10 - 5,4.8× 10 - 8～ 4.8× 10 - 5,3 .0× 10 - 8～ 3 .0× 10 - 5,5 .4× 10 - 1 0 ～ 5 .4× 10 - 7和 6.8× 10 - 1 1 ～ 6.8× 10 - 8mol/L时 ,与相应峰电流线性关系良好。方法用于同时快速测定实际样品中这些金属离子 ,获得满意结果     

Transition metal complexes of the tripodal ligand 4-(2′-pyridylmethyl)-4-azaheptane-1,7-diamine. Crystal structures of [CuLCl]ClO4 and [NiL(MeCN)2](ClO4)2

The tripodal ligand 4-(2′-pyridylmthyl)-4-azaheptane-1,7-diamine has been prepared by reaction of 2-aminemethyl pyridine with acrylonitrile, followed by the reduction of the nitrile groups. Copper(II), nickel(II), zinc(II), cobalt(III) and chromium(III) complexes of the ligand have been prepared and characterized and the crystal structures of the complexes [CuLCl]ClO₄ and [NiL(MeCN)₂](ClO₄)₂ determined. The copper complex is five coordinate with approximate square pyramidal stereochemistry with the apical position occupied by a primary amine donor. The nickel complex is octahedral with the pyridine nitrogen donor lying trans to an acetonitrile ligand.     

反应条件对Cu/Al-Ce-PILC上丙烯选择性催化还原NO反应的影响

 采用聚合羟基复合阳离子合成交联黏土Al-Ce-PILC, 经SO2-4改性后,以浸渍法制备了铜基交联黏土催化剂Cu/Al-Ce-PILC, 并将其应用于C3H6选择性还原NO的反应,考察了预处理气氛、 O2和C3H6浓度、空速、水蒸气和SO2等反应条件对催化剂性能的影响. 结果表明, He预处理后催化剂表面的Cu物种以Cu+和Cu2+两种形式存在,而H2预处理后仅以Cu+存在, NO转化率最大值由23%升至56%. 反应体系中适当的O2和C3H6浓度可促进NO还原为N2, 但过高的浓度反而可降低NO的还原活性, O2同时可起到抑制积炭、清洁催化剂表面的作用. NO转化率随着空速的增大而降低. 10%水蒸气的存在可抑制NO的还原和C3H6的氧化,其转化率曲线向高温方向位移. 但是,由于金属氧化物交联柱表面的疏水特性, Cu/Al-Ce-PILC较Cu/ZSM-5具有较强的耐湿热稳定性, NO和C3H6最大转化率仅分别下降13%和5%. SO2的存在明显抑制了催化剂的低温活性,但对高温活性有一定促进作用.     

Effects of impregnation sequence on the microstructure and performances of Cu-Co based catalysts for the synthesis of higher alcohols

Silica-supported CuCo catalysts were prepared by impregnation method with different impregnation sequence for higher alcohols synthesis. These catalysts were characterized by H2-TPR, XRD, N2 adsorption, XPS techniques and CO selective hydrogenation reaction measurement. The effects of impregnation sequence on the structure and performance of catalysts were investigated, and there were important influences on the selectivity to higher alcohols. There was a strong synergistic effect between copper and cobalt for the co-impregnated sample. The CuCo/SiO2 catalyst prepared by co- impregnation showed a better yield of total alcohols, and a higher selectivity to total alcohols which reached 51.5%.     

Cu对Ni-Cu/SiO2催化1,4-丁炔二醇加氢性能的影响

采用超临界干燥法和等体积浸渍法制备了不同Ni/Cu比例的Ni-Cu/SiO₂双金属催化剂,利用ICP、BET、XRD、H₂-TPR、H₂-TPD、NH₃-TPD等手段对催化剂进行了结构表征,考察了不同Ni/Cu比例对催化剂结构以及1,4-丁炔二醇加氢性能的影响.结果表明,少量Cu的引入不仅能够提高Ni活性物种的分散性,而且Ni-Cu双金属间的相互作用改善了NiO物种的还原性能及氢活化能力,有利于氢和1,4-丁炔二醇在活性位点的快速转化.在反应温度50℃,氢压1 MPa,反应时间3 h的加氢评价条件下,Ni/Cu比为3：1时,15Ni5Cu/SiO₂催化材料不仅可以实现BYD的完全转化,而且能够有效降低难分离副产物2-羟基四氢呋喃的含量,具有最优的加氢活性和对1,4-丁烯二醇及1,4-丁二醇的选择性.     

Effect of ruthenium substitution in layered sodium cobaltate NaxCoO2: Synthesis, structural and physical properties

Solid-state synthesis of Na_0.71Co_1−xRu_xO₂ compositions shows that ruthenium can be substituted for cobalt in the hexagonal Na_0.71CoO₂ phase up to x=0.5. The cell expands continuously with increasing ruthenium content. All mixed Co-Ru phases show a Curie-Weiss behaviour with no evidence of magnetic ordering down to 2 K. Unlike the parent phase Na_0.71CoO₂, ruthenium-substituted phases are all semiconducting. They exhibit high thermoelectric power, with a maximum of 165 μV/K at 300 K for x=0.3. The Curie constant C and Seebeck coefficient S show a non-monotonic evolution as a function of ruthenium content, demonstrating a remarkable interplay between magnetic properties and thermoelectricity. The presence of ruthenium has a detrimental effect on water intercalation and superconductivity in this system. Applying to Ru-substituted phases the oxidative intercalation of water known to lead to superconductivity in the Na_xCoO₂ system yields a 2-water layer hydrate only for x=0.1, and this phase is not superconducting down to 2 K.     

杂多酸盐在Raney Ni和Raney Co表面上的状态

采用XPS表面分析技术研究了Cu3/2PMo12O40改性Raney Ni和Raney Co的表面状态,结果表明,Raney Ni和Raney Co表面上的Cu3/2PMo12O40分子中的Cu2＋和Mo6＋发生了很大变化,Cu2＋被还原为Cu0,而Mo6＋被部分还原为Mo5＋和Mo4＋.这些变化可归因于Raney Ni和Raney Co在制备过程中表面吸附的活泼氢所致.由于Raney Ni表面吸附的氢比Raney Co表面吸附的氢的活性高,使得Raney Ni表面的Mo6＋被还原到Mo5＋和Mo4＋的量多.混合价态Mo的存在提高了羰基在催化剂表面吸附和活化的能力,同时Cu0的存在有助于羰基的加氢反应.所以,混合价态的Mo和Cu0对羰基加氢起着协同的作用.     

活性炭微柱在线流动注射预富集-火焰原子吸收快速顺序测定铜、钴、镍、镉、铅的研究

采用双柱富集的流动注射在线预富集系统与220FS顺序多元素原子吸收分光光度计联用，使用圆锥型活性炭微柱为预富集柱，在pH4～5．5范围内，以吡咯啶二硫代氨基甲酸铵(APDC)为络合剂，6mol／L HNO3为洗脱剂，实现了Cu、Co、Ni、Cd、Pb5种元素的快速顺序测定。该体系对以上5种元素的富集倍数为9．8～15．5之间，34s富集的检出限(3σ)Cu为1．81，Co为3．10，Ni为1．66，Cd为0．28，Pb为4．90μg/L；相对标准偏差Cu 1．13％；Co1．24％；Ni2．26％；Cd0．95％；Pb1．77％。