Synthesis and electrochemical performance of LiNi0.475Mn0.475Al0.05O2 as cathode material for lithium-ion battery from Ni–Mn–Al–O precursor

LiNi_0.475Mn_0.475Al_0.05O₂ cathode material was prepared by solid-state reaction using Ni–Mn–Al–O solid solution as precursor. The solid solution is of spinel structure, in which nickel, manganese, and aluminum are sufficiently mixed at atomic level. Rietveld refinement of X-ray diffraction data revealed that Al doping in LiNi_0.5Mn_0.5O₂ was significantly effective to decrease the degree of Li/Ni cation mixing. XPS analysis showed that the valence states of nickel and manganese were mainly +2 and +4, respectively. LiNi_0.475Mn_0.475Al_0.05O₂ delivered a stable capacity of about 206 mAh g⁻¹ with high reversibility. High-rate capability test was also performed.     

Sol–Gel Synthesis and Magnetic Studies of Titanium Dioxide Doped with 10% M (M=Fe,Mn and Ni)

TiO₂ nanocrystals doped with 1%, 5% and 10% Co/TiO₂ and 10% M (M=Fe, Mn and Ni) were prepared by the sol–gel technique and characterized using X-ray diffraction and SQUID. The as-prepared samples are found to be paramagnetic at room temperature, with the magnetic susceptibility following the Curie–Weiss law in the investigated range of 2–370 K. However, transformation from paramagnetism to room-temperature ferromagnetism (RTFM) for the 5% Co/TiO₂ was observed by hydrogenating the sample at 573 K while the 1% sample remained paramagnetic. As the percentage of Co was increased from 5% to 10% the Curie temperature increased from 390 K to 470 K determined via extrapolation. Transformation from paramagnetism to room-temperature ferromagnetism (RTFM) was also observed by hydrogenation of 10% Fe/TiO₂ at 573 K for 6 h. X-ray diffraction of the hydrogenated sample shows only single phase TiO₂ structure suggesting that the observed RTFM may be intrinsic but magnetic studies may suggest the possibility of Fe nanoparticles.     

Electrochemical properties and first-principle analysisof Na x [M y Mn1−y ]O2 (M = Fe,Ni) cathode

Journal of Solid State Electrochemistry - Sodium-ion batteries are the commercially and environmentally viable next-generation candidates for automobiles. Structural and electrochemical aspects are...     

Thermokinetic study of Fischer–Tropsch synthesis on Fe2Cu1 and FeCu surfaces with comparison to Fe(110) and Cu(111) catalysts by the UBI-QEP method

The purpose of this study is to predict the activation barriers and enthalpy for elementary steps in the process of Fischer–Tropsch (F-T) on the surfaces of Fe(110), Cu(111) and Fe/Cu alloys catalyst using “Unity Bond Index-Quadratic Exponential Potential” method aimed at predicting the activity and selectivity on the basis of energy criteria. The elementary steps, such as dissociation of CO, hydrogenation of carbidic carbon, C–C chain growth by insertion of CH₂ versus CO into the metal-alkyl bonds, and chain termination, which lead to hydrocarbons (alkanes versus α-olefins) or oxygenates are discussed in detail. The results show that metallic Fe(110) is necessary to produce the carbidic carbon from CO dissociation, but the synthesis of hydrocarbons and oxygenates can effectively proceed on Cu(111) surface. For optimum performance of F-T synthesis catalyst, these conflicting properties must be optimized. In this regard, we studied Fe/Cu alloy catalyst. On all the catalyst surfaces, the energetically preferred path to initiate the alkyl chain growth is via insertion of a CH_2,s group into the carbon–metal bond of a CH_3,s group. On FeCu catalyst surface, the activation barrier for termination of alkyl chain growth by β-elimination of hydrogen is found to be lower than that for α-addition of hydrogen and consequently for this catalyst, olefins are expected to form more readily than paraffins. The results of the model for a single metal surface are in agreement with the experimental data.     

Pt–M (M=Fe,Co, Ni and Cu) electrocatalysts synthesized by an aqueous route for proton exchange membrane fuel cells

Nanostructured Pt–M (M=Fe, Co, Ni, and Cu) alloy catalysts synthesized by a low temperature (70 °C) reduction procedure with sodium formate in aqueous medium have been investigated for oxygen reduction in sulfuric acid and as cathodes in single proton exchange membrane fuel cells (PEMFC). The Pt–M alloy catalysts show improved catalytic activity towards oxygen reduction compared to pure platinum. Among the various alloy catalysts investigated, the Pt–Co catalyst shows the best performance with the maximum catalytic activity and minimum polarization occurring at a Pt:Co atomic ratio of around 1:7. While mild heat treatments at moderate temperatures (200 °C) improve the catalytic activity due to a cleaning of the surface oxides, annealing at elevated temperatures (900 °C) degrade the activity due to an increase in particle size.     

Synthesis of Li3Ni x V2−x (PO4)3/C cathode materials and their electrochemical performance for lithium ion batteries

Li₃Ni _x V_2?x (PO₄)₃/C (x?=?0, 0.02, 0.04 and 0.06) samples have been synthesized via an improved sol–gel method. X-ray diffraction patterns indicate that the structure of the prepared samples retains monoclinic, and the single phase has not been changed with Ni doping. From the analysis of electrochemical performance, the Li₃Ni_0.04?V_1.96(PO₄)₃/C sample exhibits the best electrochemical property. It delivers a discharge capacity of 112.1 mAh?g^?1 with capacity retention of 95.2 % over 300 cycles at 10 C rate in the range of 3.0–4.8 V; cyclic voltammetry and electrochemical impedance spectra testing further prove that the electrochemical reversibility and lithium ion diffusion behavior of Li₃V₂(PO₄)₃ have also been effectively improved through Ni doping.     

Nano magnetite supported phthalocyanine complexes of Cu(II) and Fe(II) as new heterogeneous effective catalysts for synthesis of β-amido ketones

Abstract

In this study, a novel, heterogeneous and reusable catalyst prepared by the coordinative anchoring of metal(II) phthalocyanine complexes (M: Fe, Cu) on the guanidine-functionalized magnetic nanoparticles was reported. The synthesized catalysts were characterized by scanning electron microscopy (SEM), powder X-ray diffraction (XRD), vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA), and FT-IR measurements. The catalysts were used successfully in the synthesis of β-amido ketones. This method provides several advantages including little catalyst loading, absence of any tedious workup or purification and at least six times reusability of the catalyst without any remarkable change in the catalytic activity.     

Ion-Exchange Processes M(II) → Fe(III) and Fe(III) → M(II) in Metal Hexacyanoferrate(II) Gelatin-Immobilized Matrices (M = Mn,Co, Ni,Cu, Zn,Cd)

Ion-exchange reactions M²⁺ Fe³⁺ and Fe³⁺ M²⁺ (M = Mn, Co, Ni, Cu, Zn, Cd) were studied in metal(II) hexacyanoferrate(II) gelatin-immobilized matrices M₂[Fe(CN)₆] in contact with aqueous FeCl₃ solutions and Fe₄[Fe(CN)₆]₃ in contact with aqueous MCl₂ solutions. It was shown that in both cases, M²⁺ was replaced by Fe³⁺ and Fe³⁺ was replaced by M²⁺ to some extent, but no complete replacement was observed in the M₂[Fe(CN)₆]–FeCl₃ or Fe₄[Fe(CN)₆]₃–MCl₂ systems under study. No electrophilic substitution Fe³⁺ Mn²⁺ was found to occur in any noticeable degree during the contact of Fe₄[Fe(CN)₆]₃ with aqueous MnCl₂ solutions even when this contact occurred for 1 h and longer.     

Graphene oxide–starch composite as an efficient adsorbent for removing Cu(II): removal performance and adsorption mechanism

Research on Chemical Intermediates - Water pollution caused by heavy metals is a severe environmental issue. In this work, a graphene oxide–starch composite (GO/WS) was facilely prepared via...     

(Cu/Ni)–Al layered double hydroxides@Fe3O4 as efficient magnetic nanocomposite photocatalyst for visible-light degradation of methylene blue

Research on Chemical Intermediates - A new magnetic nanocomposite based on layered double hydroxides (LDHs) was synthesized by coprecipitation of (Cu/Ni)–Al LDHs and nano-Fe3O4 and...     

Performance of Na0.44Mn1−xMxO2 (M = Ni,Mg; 0 ≤ x ≤ 0.44) as a cathode for rechargeable sodium ion batteries

Journal of Solid State Electrochemistry - The influence of partial substitution of manganese by nickel or magnesium in Na0.44MnO2on cathode performance in sodium ion batteries has been...     

Synthesis and thermal properties of poly(styrene-co-acrylonitrile)-graft-polyethylene glycol copolymers as novel solid–solid phase change materials for thermal energy storage

A novel poly(styrene-co-acrylonitrile)-graft-polyethylene glycol(SAN-g-PEG) copolymer was synthesized as new solid–solid phase change materials(SSPCMs) by grafting PEG to the main chain of poly(styrene-co-acrylonitrile). The chemical structure of the SAN-g-PEG was confirmed by the Fourier transform infrared(FT-IR) and proton nuclear magnetic resonance(1H NMR) spectroscopy techniques. The thermal energy storage properties and the storage durability of the SAN-g-PEG were investigated by differential scanning calorimetry(DSC). The SAN-g-PEG was endowed with the solid–solid phase transition temperatures within the range of 23–36 8C and the latent heat enthalpy ranged from 66.8 k J/kg to 68.3 k J/kg. Thermal cycling tests revealed that the SAN-g-PEG kept great heat storage durability after 1000 thermal cycles. The thermal stability was evaluated by a thermal gravity analysis(TGA), and the initial decomposition temperature(Td) of SAN-g-PEG is 350 8C, which proves that the SAN-g-PEG possessed good thermal stability.     

Use of 2-(tert-butoxy)-N-(3-carbamothioylphenyl)acetamide and graphene oxide for separation and preconcentration of Fe(Ⅲ),Ni(Ⅱ),Cu(Ⅱ) and Zn(Ⅱ) ions in different samples

A simple and selective method using a column packed with graphene oxide(GO) as a solid phase extractant has been developed for the multi-element preconcentration of Fe(Ⅲ),Ni(Ⅱ),Cu(Ⅱ) and Zn(Ⅱ)ions prior to flame atomic absorption spectrometric determinations.The method is based on the sorption of mentioned ions on synthesized GO using 2-(tert-butoxy)-N-(3-carbamothioylphenyl)acetamide as a chelating agent.Several parameters on the extraction and complex formation were optimized.Under the optimized conditions(pH 6,flow rate 9 mL/min),metal ions were retained on the column,then quantitatively eluted by HNO3solution(5 mL,3.0 mol/L).The preconcentration factor was calculated as250.The detection limits for the analyte ions of interest were found in the range of 0.11 ng/mL(Ni2+) to0.63 ng/mL(Cu2+).The column packed with GO was adequate for metal ions separation in matrixes containing alkali,alkaline earth,transition and heavy metal ions.     

Quantum-chemical modeling of the molecular structures of (555)macrotricyclic chelates in M(II) ion–thiooxamide–glyoxal ternary systems (M = Mn,Fe, Co,Ni, Cu,Zn)

The thermodynamic and geometric parameters of isomeric macrotricyclic Mn(II), Fe(II), Co(II), Ni(II), Cu(II), and Zn(II) complexes that can form upon the complexation of the corresponding hexacyanoferrates( II) with thiooxamide H₂N–C(=S)–C(=O)–NH₂ and glyoxal HC(=O)–CH(=O) in gelatin-immobilized matrices have been calculated by the OPBE/TZVP DFT method with the use of the Gaussian09 program package. It has been found that a complex with the MN₄ chelate core is most stable for M = Mn, Fe, Co, Ni, and Zn, and the MN₂S₂ core is most stable for M = Cu. Bond lengths and bond angles have been reported, and it has been noted that in all complexes, except the Zn(II) one, the chelate core and three fivemembered chelate rings are almost planar.     

Synthesis and electrochemical characteristics of xLi2MnO3–(1−x)Li(Mn0.375Ni0.375Co0.25)O2 (0.0 ≤ x ≤ 1.0) thin film cathode for lithium rechargeable micro batteries

We have compared the structure, microstructure, and electrochemical characteristics of xLi₂MnO₃–(1−x)Li(Mn_0.375Ni_0.375Co_0.25)O₂ (0.0 ≤ x ≤ 1.0) thin films with their bulk cathode laminate counterparts of identical compositions. Pure Li(Mn_0.375Ni_0.375Co_0.25)O₂ as well as the synthesized composite films partially transform into cubic spinel structure during charge–discharge cycling. In contrast, such layered to spinel phase transformation has only been identified in bulk cathode laminates with x ≥ 0.75. At a current density 0.05 mAcm⁻², the discharge capacity of Li(Mn_0.375Ni_0.375Co_0.25)O₂ thin film was measured to be ∼60 μAhcm⁻². The discharge capacity (∼217 μAhcm⁻²) was markedly improved in x∼0.5 composite thin film. The capacity retention after 20 charge discharge cycles are improved in composite films; however, their capacity fading could not be eliminated completely.     

First-principles investigation of the structural stability and electronic properties of LiV1–xMxPO4F (M = Mn,Fe, Co,and Ni)

Journal of Solid State Electrochemistry - Density functional theory calculations corrected by on-site Coulomb interactions have been conducted to study the crystal structure and electronic property...     

Pt/Ni(OH)2–NiOOH/Pd multi-walled hollow nanorod arrays as superior electrocatalysts for formic acid electrooxidation

The catalytic activity and durability are crucial for the development of high-performance electrocatalysts. To design electrocatalysts with excellent electroactivity and durability, the structure and composition are two important guiding principles. In this work, novel Pt/Ni(OH)₂–NiOOH/Pd multi-walled hollow nanorod arrays (MHNRAs) are successfully synthesized. The unique MHNRAs provide fast transport and short diffusion paths for electroactive species and high utilization rate of catalysts. Because of the special surface and synergistic effects, the Pt/Ni(OH)₂–NiOOH/Pd MHNRA electrocatalysts exhibit high catalytic activity, high durability and superior CO poisoning tolerance for the electrooxidation of formic acid in comparison with Pt@Pd MHNRAs, commercial Pt/C, Pd/C and PtRu/C catalysts.     

On the sol–gel synthesis and catalytic activity of Ce1−xAxO2−δ (A = Pr, Sm, Gd) SOFCs anode materials for reforming of methane

A sol–gel route to synthesize nanocrystalline praseodymium-, samarium- and gadolinium-doped ceria powders for solid oxides fuel Cells SOFCs is presented. The method involves metal nitrates with propionic acid (both as chelating ligand and solvent), gel formation, liquid nitrogen quenching, drying at 150 °C/24 h, and finally decomposition at 450 °C in nitrogen followed by calcination at 650 °C in air. TG–DTA, BET, XRD, FTIR, UV–vis and catalytic tests were used to characterize the samples. Ce_0.8Pr_0.2O_2?δ sample exhibited the best catalytic performance in methane steam reforming under water deficient conditions, closely followed by Ce_0.9Gd_0.1O_2?δ, Ce_0.8Sm_0.2O_2?δ and Ce_0.8Gd_0.2O_2?δ catalysts. The superior catalytic performance of Ce_0.8Pr_0.2O_2?δ sample was attributed to the existence of praseodymium species (Pr⁴⁺/Pr³⁺) strongly interacting with ceria. The two systems act synergistically in the catalytic steam reforming of methane.