Electrolytic composites of iron sulfides with graphite in a prototype lithium battery

Electrolytic composites of iron sulfides FeS and Fe₃S₄ with natural graphites of GAK and EUZ-3 brands and Chinese graphite were synthesized in thin layers and studied in a prototype lithium battery.     

Structural and electronic properties of lithium ion battery anode material LiMN (M = Ni, Co, Cu)

The structural and electronic properties of anode materials LiMN (M = Ni, Co, Cu) for lithium ion batteries have been studied by the first-principles method. The calculations reveal different bonding characteristics for LiMN (M = Ni, Co, Cu). The Li–N bond on the LiN planes shows covalent mixed with ionic characters, with the covalent interaction strengthened and ionic one weakened gradually from LiNiN to LiCoN and then to LiCuN. In the direction of N–M chains, the bonding characteristics are analogous on the whole. The N–M bonding shows both ionic and covalent characters again, while the covalent interaction slightly weakened in sequence. Electronic structure calculations suggest that LiMN (M = Ni, Co, Cu) are all metallic, where the LiNiN is of anisotropic conductivity along the directions of N–Ni chains, while for LiCoN and LiCuN, electrons can also be feebly conductive on the LiN planes besides along the linear N–Co and N–Cu chains.     

电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰

采用电感耦合等离子体原子发射光谱法测定钨合金中镍、铁、钴和锰的含量。优化的试验条件如下:1柠檬酸溶液用量为2mL;2过氧化氢溶液用量为12mL;3称样量为0.100 0g;4氨水溶液用量为2mL。选择镍、铁、钴、锰的分析谱线分别为221.647,233.280,228.616,259.373nm。4种元素在一定的质量浓度范围内与其发射强度呈线性关系,方法的检出限(3s/k)在0.018~0.083mg·L-1之间。方法应用于标准物质(JBWY05901)的分析,测定值与认定值相符。方法用于生产样品和合成样品的分析,测定值的相对标准偏差(n=6)在0.72%~3.9%之间。     

铁钴镍氢氧化物的光催化性能研究

20世纪70年代Fujishima与Hondo报道了在光电池中光辐射TiO2可以引发水的氧化还原反应并产生氢气以来,关于光催化降解废水的研究渐渐引起人们的高度重视。     

Enhancing the efficiency of using electroplated iron and cobalt sulfides with a sublayer of NiC composite in a lithium battery

The efficiency of using in a lithium battery transition metal sulfides electroplated on a metal support strongly depends on the kind and relief of the support. To make the nickel support rougher for enhancing the adhesion of sulfides, it was electroplated with a nickel–carbon composite, NiC. The discharge capacity and the efficiency of cycling of iron and cobalt sulfides electroplated with a NiC sublayer were higher than in the case when the sulfides were electroplated on a smooth nickel support without composite coating.     

Thermal behavior of Ni,Co and Fe succinates embedded in silica matrix

This paper presents the thermal behavior of Co, Ni and Fe succinates obtained by sol-gel synthesis using Co(II), Ni(II) and Fe(III) nitrates, 1,4-butanediol and tetraethyl orthosilicate as reactants. The thermal analysis revealed the formation of succinates at 413–453 K and their decomposition to ferrites at 503–623 K. The rate constants for the decomposition of succinates to ferrites, calculated using the isotherms at 473, 523, 573 and 623 K, were used to determine the activation energy of each ferrite (NiFe₂O₄, Ni_0.3Co_0.7Fe₂O₄, Ni_0.7Co_0.3Fe₂O₄ and CoFe₂O₄) embedded in the silica matrix. By increasing the Ni content in the mixed Ni–Co ferrites, the activation energy decreases from 13.530 to 1.944 kJ mol^?1. The formation and decomposition of succinate precursors and the formation of silica matrix were confirmed by FT-IR spectroscopy, while the formation of CoFe₂O₄ and NiFe₂O₄ single-phases embedded in the silica matrix was confirmed by X-ray diffraction analysis. The nanocrystallites size decreases from 31.7 (CoFe₂O₄) to 18.5 nm (NiFe₂O₄). The optical band gap of mixed Co–Ni ferrites was significantly higher than that corresponding to CoFe₂O₄. The photocatalytic activity of the samples was evaluated against Rhodamine B under visible light. All the samples have photocatalytic activities, the best performance being obtained in the case of Ni_0.7Co_0.3Fe₂O₄.

     

Structure of Fe/Co/Ni hexacyanoferrate as probed by multiple edge X-ray absorption spectroscopy

The structural parameters in selected cobalt and mixed cobalt/nickel hexacyanoferrates have been determined by X-ray absorption spectroscopy. The presence of two or three metals in the sample requires the use of a highly efficient multiple edge analysis. The typical structure of mixed hexacyanoferrates coupled with a suitable data analysis program, GNXAS, allow us to determine structural parameters considering a very high number of experimental points. The first data analysis of three contiguous edges (Fe, Co, and Ni K-edges), the structural parameters of which are entirely correlated, is presented. The advantages and limitations of the multiple edge approach are underlined and placed in the context of the previous studies. The CN bond length has been determined with a statistical error of few thousandths of an angstrom.     

Methane Combustion Over Fe, Co and Ni Modified Manganese Oxide Catalysts

Fe-Mn, Co-Mn and Ni-Mn composite oxide catalysts based on high specific surface area MnO₂ precursor were prepared and applied to catalytic combustion of CH₄. Results were compared with that of unmodified MnOx and 1wt.% Pd/-Al₂O₃. Below 450°C, manganese oxide catalysts show higher activity than Pd/-Al₂O₃, while the modified manganese oxide catalysts exhibit higher activity than the unmodified one below 420°C. All catalysts were characterized by means of N₂-BET, XRD, TG-DTA and H₂-TPR. Due to the interaction between Fe, Co or Ni oxides and manganese oxide, the activity of the oxygen species of the modified catalysts is improved, which leads to the increase of their CH₄ combustion activity.     

Adsorption isobars of nitrogen on Ni,Co, Fe,Mn, and Cr

Russian Chemical Bulletin -     

First principles investigations of Fe,Co, Ni in model honeycomb carbon networks

The behaviors of ferromagnetic transition metals of the first period: Fe, Co and Ni are examined within density functional theory calculations in two dimensional carbon extended networks using model structure LiC₆. Around geometry optimized structures, the energy-volume equations of states considering non magnetic and spin polarized configurations established ferromagnetic ground states with magnetizations –reduced with respect to the metals’– of 2 μ_B for FeC₆ and 1 μ_B for CoC₆ while no magnetic solution could be identified for NiC₆. In the D_6h point group of the P6/mmm space group l_m decomposition of the d states results with increasing energy into doublet state E_1g with d(x²-y²) and d(xy); singlet state A_1g d(z²) and doublet state E_2g d(xz) and d(yz) lying on E_F and responsible of the onset of magnetic moments. This was mirrored via molecular orbital approach with a construct of Fe embedded between two extended carbon networks thus validating the model structure proposed for TC₆ compounds. The 100% polarization in one spin channel allows proposing potential uses in spintronics applications.     

Surface fluorination and electrochemical behavior of petroleum cokes graphitized at medium and high temperatures for secondary lithium battery

The surface structure and electrochemical performance have been investigated of petroleum cokes heat-treated at 2100 and 2600 °C (abbreviated to PC2100 and PC2600) and those fluorinated by elemental fluorine at 200 and 300 °C. XPS study indicated that surface fluorine was covalently bonded to carbon and surface fluorine contents were in the range of 4.9-17.8 at.%. Surface oxygen was reduced by fluorination. BET surface areas were nearly the same before and after fluorination. Fluorination enhanced D-band intensity in two Raman shifts observed at 1580 cm⁻¹ (G-band) and 1360 cm⁻¹ (D-band), indicating the increase in the surface disordering. At a high current density of 150 mA/g, the capacity increase was observed for PC2100 fluorinated at 200 °C and for PC2600 fluorinated at 200 and 300 °C. The most interesting result was the increase in first coulombic efficiencies by surface fluorination. First columbic efficiencies for PC2600 fluorinated at 300 °C were increased by 12.1% at 60 mA/g and by 25.8% at 150 mA/g, respectively. The impedance measurements showed that the resistances of surface films on carbon electrodes were increased by fluorination, however, the charge transfer resistances were decreased by 12.3% for PC2100 fluorinated at 200 °C, and by 27.5 and 6.4% for PC2600 fluorinated at 200 and 300 °C, respectively. The reduction of the charge transfer resistances was consistent with increase in the charge capacities for PC2100 fluorinated at 200 °C and PC2600 fluorinated at 200 and 300 °C.     

Chemical probes of metal cluster structure - Fe,Co, Ni and Cu

Chemical reactivity is one of the few methods currently available for investigating the geometrical structure of isolated transition metal clusters. In this paper we summarize what is currently known about the structures of clusters of four transition metals, Fe, Co, Ni, and Cu, in the size range from 13 to 180 atoms. Chemical probes used to determine structural information include reactions with H₂ (D₂), H₂O, NH₃ and N₂. Measurements at both low coverage and at saturation are discussed.     

IR-spectroscopic characterization of acetophenone complexes with Fe+, Co+, and Ni+ using free-electron-laser IRMPD

The gas-phase complexes M(+)(acet)(2), where M is Fe, Co, or Ni and acet is acetophenone, were studied spectroscopically by infrared multiple-photon dissociation (IRMPD) supported by density functional (DFT) computations. The FELIX free electron laser was used to give tunable radiation from approximately 500 to 2200 cm(-1). The spectra were interpreted to determine the metal-ion binding sites on the ligands (oxygen (O) or ring (R)) and to see if rearrangement of the ligand(s) to toluene plus CO occurred. For Ni(+), O binding was found to predominate (similar to the previously studied Cr(+) case), with less than approximately 10% of R-bound ligands in the population. For Co(+), a roughly equal mixture of R-bound and O-bound ligands was present; based on the computed thermochemistry, the OR complex was considered likely to predominate. Fe(+) complexes appeared largely O-bound, but with clear evidence for some R-binding. The exceptionally large extent of R binding for Co(+) highlights the special affinity of this metal ion for aromatic ring ligands. In contrast, the predominant O binding for Ni(+) emphasizes the especially high metal-ion affinity of the O site of acetophenone compared with other ligands such as anisole where R binding of Ni(+) predominates. The spectra did not indicate significant intracomplex rearrangement of ligands to toluene plus CO, and in particular for the Co(+) case the absence of a metal-bound C triple bond O stretching peak near 2100 cm(-1) strongly ruled out such a rearrangement.     

Fe、Co、Ni双齿巯基配合物从头算研究

运用Gaussian94量子化学程序包，采用LanL2DZ基组，对Fe（Ⅲ）、Co（Ⅲ）、Ni（Ⅱ）与Hmpo（2-巯基氧化吡啶）的双齿配合物Fe（mpo）3、Co（mpo）3、Ni（mpo）2进行从头算研究。讨论这些配合物的稳定性、分子轨道能量、原子电荷分布以及最高占据轨道的特征等，为过渡金属双齿配合物的合成、结构分析及其在酶与蛋白质中的活性部位研究提供一些理论参考．     

Enhancement of catalytic degradation of perchlorate using novel stabilized Ni/Fe/Zn nanoparticles

The stabilized Ni/Fe/Zn nanoparticles (S-Ni/Fe/Zn NPs) were successfully synthesized in the presence of starch as a stabilizing agent through the borohydride reductive method. The physicochemical properties of the prepared nanoparticles were characterized by FE-SEM, XRD, and EDS. The results showed that the synthesized S-Ni/Fe/Zn NPs were spherical in shape and they have nearly uniform distribution with the particle size of 20–60 nm. In the following, the prepared nanoparticles were used for the catalytic degradation of perchlorate to chloride ion from aqueous solutions. The main factors controlling the degradation of perchlorate, such as the pH, the amount of nanoparticles, and the reaction time were optimized by using an experimental design based on the response surface methodology. Under the optimum conditions, the degradation efficiency of perchlorate was 98%. Also, the degradation data were modeled using the pseudo-first-order kinetic equations which describe best the degradation kinetic. The rate constant (k _obs) for the degradation step was 0.0353 min^?1 at 303 K, and the activation energy (E _a) was calculated to be 13.38 kJ mol^?1. However, the S-Ni/Fe/Zn NPs were successfully applied to the degradation of perchlorate in the well water and the industrial wastewater samples.     

Thermal decomposition of ammonium metavanadate doped with Fe,Co or Ni hydroxides

The thermal decomposition of pure ammonium metavanadate (AMV) and of AMV doped with Fe³⁺,Co²⁺ or Ni²⁺ ions was investigated by TG, DTA, IR and X-ray diffraction. The results obtained revealed that the presence of these dopants enhances the formation of the intermediate compounds V₂O₅ solid. Some of the V⁵⁺ ions of the V₂O₅ lattice seemed to be reduced to V⁴⁺ ions. The activation energies of the different decomposition stages for all samples were calculated. The doped solids calcined at 450°C were characterized by the determination ofSbet and by electrical conductivity measurements. The mechanisms by which these ions affect the properties of the solids produced are discussed in relation to the defect structure created by the doping process.

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Zusammenfassung Mittels TG, DTA, IR und Röntgendiffraktion wurde die thermische Zersetzung von reinem Ammoniummetavanadat (AMV) und von AMV, versetzt mit Fe³⁺, Co²⁺ oder Ni²⁺, untersucht. Die Ergebnisse zeigen, daß die Bildung von Zwischenprodukten und festem V₂O₅ durch die Gegenwart der Zusätze begünstigt wird. Einige der V⁵⁺-Ionen des V₂O₅ Gitters scheinen zu V⁴⁺-Ionen reduziert zu sein. Für alle Proben wurde die Aktivierungsenergie der verschiedenen Zersetzungsschritte berechnet. Die versetzten Feststoffe, die bei 450°C kalziniert wurden, konnten durch die Bestimmung vonSbet und durch elektrische Leitfähigkeitsmessungen charakterisiert werden. Der Mechanismus, über welchen diese Ionen die Eigenschaften der Feststoffe beeinflussen, wurde hinsichtlich der hervorgerufenen Defektstruktur diskutiert.

     

用于电化学水氧化的铁、镍、钴金属及其二元金属纳米颗粒比较研究

从环境兼容角度来设计应用于氧析出反应的电催化剂是否有效、耐用和廉价对能源转化过程至关重要. 本文报告了一种快速制备低成本、原料丰富的金属催化剂制备方法。通过一步电化学沉积法在钛金属基材上制备了铁、镍、钴金属及其钴镍、钴铁二元金属纳米颗粒. 采用场发射电子显微镜 (FE-SEM), 能量散射X-射线能谱 (EDX), X-射线衍射光谱 (XRD), X-射线光电子能谱 (XPS)和电化学技术对制备的不同纳米颗粒进行了表征. 电化学结果显示,在合成的五种钛基金属纳米催化剂中, 钛基上沉积钴金属纳米颗粒(Ti/Co)电极在0.l mol·L^-1氢氧化钾溶液中氧析出反应的电催化活性最好,0.70 V(相对于银/氯化银电极)的电流密度为10.0 mA·cm^-2. 经优化后Ti/Co电极的过电位(η)很小,当电流密度为10.0 mA·cm^-2时η为0.43 V,质量活性高达105.7 A·g^-1,逆转频率(TOF)值为1.63×10^-3 s^-1, 这些与当前最好的碳载铂(Pt/C)和氧化钌(RuO₂)电催化剂的性能相当. 此外,通过计时电位技术对优化后Ti/Co电极的耐久性进行了测试, 发现该电极在碱性溶液中氧析出反应的稳定性良好. 本工作制备的钛金属基材上电化学沉积金属钴纳米颗粒具有高催化活性、高稳定性、原料来源丰富、廉价且易于大规模生产,在工业化水分解领域具有潜在的应用前景.