Formation of solid solution and its effect on lithium insertion schemes for advanced lithium-ion batteries: X-ray absorption spectroscopy and X-ray diffraction of LiCoO2, LiCo1/2Ni1/2O2 and LiNiO2

The X-ray absorption spectra (XAS) of LiCoO₂, LiCo_1/2Ni_1/2O₂ and LiNiO₂ were examined together with X-ray diffraction (XRD). Co and Ni K-edge XANES spectra of LiCo_1/2Ni_1/2O₂ are quite similar to that of LiCoO₂ or LiNiO₂, suggesting that electronic states of Co and Ni in LiCo_1/2Ni_1/2O₂ are Co³⁺ and Ni³⁺. Analytical results of Co and Ni K-edge EXAFS oscillations on the first coordination shell of nickel and cobalt ions in LiCo_1/2Ni_1/2O₂ indicate that the local environment around the targeted species is the same as that in LiCoO₂ or LiNiO₂. Since there is no doubt about the crystal and electronic structures of LiCoO₂ and LiNiO₂, the results indicate that LiCo_1/2Ni_1/2O₂ consists of low-spin states of Co³⁺ and Ni³⁺ distributed at equivalent positions in triangular lattice of sites forming homogeneous transition metal oxide layers. Thus, XAS complements XRD in describing solid solution LiCo_1/2Ni_1/2O₂ of LiCoO₂ and LiNiO₂. The electrochemical behaviors of LiCoO₂, LiCo_1/2Ni_1/2O₂ and LiNiO₂ are also restated and the effects of the formation of solid solution on the change in lattice dimension during topotactic electrochemical reactions are discussed.     

Syntheses and characterizations of complex perovskite oxynitrides LaMg1/3Ta2/3O2N, LaMg1/2Ta1/2O5/2N1/2, and BaSc0.05Ta0.95O2.1N0.9

The following complex oxynitride perovskites have been prepared: LaMg_1/3Ta_2/3O₂N, LaMg_1/2Ta_1/2O_5/2N_1/2, and BaSc_0.05Ta_0.95O_2.1N_0.9. Synchrotron X-ray powder diffraction analyses show that LaMg_1/3Ta_2/3O₂N and LaMg_1/2Ta_1/2O_5/2N_1/2 are isostructural to the oxide La₂Mg(Mg_1/3Ta_2/3)O₆ (space group P2₁/n), whereas BaSc_0.05Ta_0.95O_2.1N_0.9 has a simple cubic symmetry similarly to BaTaO₂N. The orderings of octahedral cations are markedly diminished in the above oxynitrides, as compared with the related oxides such as La₂Mg(Mg_1/3Ta_2/3)O₆ and Ba₂ScTaO₆. The optical band gaps are similar for the homologous compositions, LaMg_1/3Ta_2/3O₂N, LaMg_1/2Ta_1/2O_5/2N_1/2 and LaTaON₂ (1.9 eV), and BaSc_0.05Ta_0.95O_2.1N_0.9 and BaTaO₂N (1.8 eV), while the absorption edges become broader for the complex derivatives. As revealed from the impedance spectroscopic analysis, the oxynitrides have clearly different dielectric components from those of comparable oxides containing Ta⁵⁺. Impedance spectroscopy reveals interesting capacitor geometry in BaSc_0.05Ta_0.95O_2.1N_0.9 in which the semiconducting oxynitride grains are separated by insulating secondary phases. Most notably BaSc_0.05Ta_0.95O_2.1N_0.9 has a bulk component with a high relative permittivity (κ=7300) and the grain boundary component with an even higher κ.     

Ethylcyclopentane ring opening reaction over PtGe/Al2O3 catalysts prepared by controlled surface reaction

Platinum-germanium catalysts supported on a non-acidic Al₂O₃ have been prepared by adding Ge in amounts corresponding nominally to 1/8 (PtGe1/8/Al₂O₃); 1/2 (PtGe1/2/Al₂O₃); 1 (PtGe1/Al₂O₃) and 2 (PtGe2/Al₂O₃) monolayers by controlled surface reaction of Ge(n-C₄H₉)₄ to Pt/Al₂O₃. These catalysts were characterized by electron microscopy (TEM), FTIR of CO adsorption and H₂ chemisorption. The ring opening of ethylcyclopentane (ECP) was studied as a test reaction between 543 and 633 K. PtGe1/8/Al₂O₃ catalyst produced the most ring opening products (ROP) in the whole temperature range. A good agreement with statistical values of ROP was observed at low temperature, but at higher temperature, the opening became selective, producing mostly heptane. Bimetallic catalysts PtGe1/Al₂O₃ and PtGe2/Al₂O₃ led to a nonselective hydrogenolysis, similar to the monometallic platinum catalyst Pt/Al₂O₃. The catalysts PtGe1/Al₂O₃ and PtGe2/Al₂O₃ produced ROP with the lowest selectivity; instead, much aromatics and fragments were formed, in increasing amounts above 600 K.     

Sonocatalytic degradation of C.I. Reactive Red 198 in H2O2-based Systems

This study elucidated the effects of pH on the decolorization of C.I. Reactive Red 198 (RR198) in US, UV/H₂O₂, US/H₂O₂ and UV/US/H₂O₂ systems. The synergistic effects in US/H₂O₂ and UV/US/H₂O₂ systems were also evaluated. At pH 4, 7 and 10, the decolorization rates of RR198 followed the order UV/US/H₂O₂ > UV/H₂O₂ > US > US/H₂O₂.     

Generation,spectroscopic characterization and antioxidant activity of tetracoordinate and hexacoordinate complexes of diethylgermanium(IV) of relatively sterically undemanding N-protected amino acids and sterically demanding heterocyclic β-diketones containing radical sensitive Ge-O bond

Two new sets of diethylgermanium(IV) complexes of the types Et₂GeA₂ and Et₂GeB₂ have been generated by the reactions of diethylgermanium(IV) dichloride with sodium salts of N-protected amino acids (AH) [where AH = , R = -CH(CH₃)C₂H₅: A₁H, R = -CH₂CH(CH₃)₂: A₂H, R = -CH(CH₃)₂: A₃H] and with sodium salts of sterically demanding heterocyclic β-diketones (BH) [where BH = , R’ = -C₆H₅: B₁H, R’ = -p-(Cl)C₆H₄: B₂H, R’ = -CH₃: B₃H, R = -C₂H₅: B₄H], respectively in 1:2 molar ratios in refluxing dry benzene. Plausible structures of these complexes were suggested on the basis of physico-chemical and spectroscopic studies. It is suggested that the complexes of the types Et₂GeA₂ and Et₂GeB₂ contain four coordinated and six coordinated germanium centers, respectively. The ligands and organogermanium(IV) complexes were evaluated for their free radical scavenging activity by DPPH method. These compounds/complexes demonstrate potential antioxidant activity.     

Monophosphine and diphosphine ligands for diplatinum polyynediyl complexes: Efficient syntheses of new functionality-containing systems and model compounds

Br(CH₂)₄Br and NaO(CH₂)₂CHCH₂ react under suitable conditions to give Br(CH₂)₄O(CH₂)₂CHCH₂ (55%), which is treated with KPPh₂ to yield the ether-containing phosphine Ph₂P(CH₂)₄O(CH₂)₂CHCH₂ (83%). The reaction of CH₃CH₂OC(O)CHC(CH₃)₂ and BrMg(CH₂)₃CHCH₂ in the presence of CuCl (cat.) and ClSiMe₃ yields CH₃CH₂OC(O)CH₂C(CH₃)₂(CH₂)₃CHCH₂ (67%), which is reduced to an alcohol that is brominated, reacted with Grubbs’ catalyst, hydrogenated, and treated with KPPh₂ to give the bis(geminally dimethylated) diphosphine Ph₂P(CH₂)₂C(CH₃)₂(CH₂)₈C(CH₃)₂(CH₂)₂PPh₂ (47% overall). The photochemical reaction of I(CF₂)₈I and H₂CCHCH₂SnBu₃ yields H₂CCHCH₂(CF₂)₈CH₂CHCH₂ (52%), which is converted with 9-BBN to a diol (92%) that is brominated and treated with LiPR₂ to give the fluorinated diphosphines R₂P(CH₂)₃(CF₂)₈(CH₂)₃PR₂ (R = a, p-tol, 67%; b, t-Bu, 69%; c, o-tol, 86%). Reactions of Br(CH₂)_mBr and LiPR₂ similarly yield R₂P(CH₂)_mPR₂ (m/R = 8/a, 95%; 14/a, 96%; 14/p-C₆H₄-t-Bu, 98%). Reactions of KPPh₂ with Br(CH₂)_m′CHCH₂and Br(CH₂)₇CH₃ give the corresponding monophosphines Ph₂P(CH₂)_m′CHCH₂ (m′ = 7, 82%; 10, 84%) and Ph₂P(CH₂)₇CH₃ (85%). When the former is combined with [Pt(μ-Cl)(C₆F₅)(tht)]₂ (tht = tetrahydrothiophene), trans-(C₆F₅)(Ph₂P(CH₂)_m′CHCH₂)₂PtCl (77-70%) is isolated. When the latter (excess) is combined with trans,trans-(C₆F₅)(p-tol₃P)₂Pt(CC)₄Pt(Pp-tol₃)₂(C₆F₅) (RT, 65 °C), trans,trans-(C₆F₅)(Ph₂P(CH₂)₇CH₃)₂Pt(C C)₄Pt(Ph₂P(CH₂)₇CH₃)₂(C₆F₅) (53%) is isolated.     

Syntheses,structures and comparative electrochemical study of π-acetylene complexes of cobalt

The preparation and characterization of the complexes [Co₂(CO)₄(μ-dppm)]₂(μ-η²-Me₃SiC₂(CC)₂C₂H) (2), [Co₂(CO)₄(μ-dppm)]₂(μ-η²-HC₂(CC)₂C₂H) (3), Co₂(CO)₄(μ-dmpm)(μ-η²-Me₃SiC₂CCSiMe₃) (4), Co₂(CO)₄(μ-dmpm)(μ-η²-Me₃SiC₂CCH) (5), [Co₂(CO)₄(μ-dmpm)]₂(μ-η²-Me₃SiC₂(CC)₂C₂SiMe₃) (6) and [Co₂(CO)₄(μ-dmpm)]₂(μ-η²-HC₂(CC)₂C₂H) (7) are described. A comparative electrochemical study of all these complexes and the related [Co₂(CO)₄(μ-dppm)]₂(μ-η²-Me₃SiC₂(CC)₂C₂SiMe₃) (1), Co₂(CO)₄(μ-dppm)(μ-η²-Me₃SiC₂CCH) and Co₂(CO)₄(μ-dppm)(μ-η²-HC₂CCH) is presented by means of the cyclic and square-wave voltammetry techniques. Crystals of 2 and 3 suitable for single-crystal X-ray diffraction were grown and the molecular structures of these compounds are discussed.     

Crystal structures of Na1/2Ln1/2TiO3 (Ln: La, Eu, Tb)

Neutron powder diffraction studies of Na_1/2La_1/2TiO₃ and Na_1/2Tb_1/2TiO₃, and a synchrotron X-ray powder diffraction study of Na_1/2Eu_1/2TiO₃ have been carried out. Rietveld refinement of the structures confirmed that Na_1/2Eu_1/2TiO₃ and Na_1/2Tb_1/2TiO₃ crystallizes in GdFeO₃ type of structure (space group Pbnm). The ambiguity in the literature regarding the crystal structure of Na_1/2La_1/2TiO₃ has been resolved and the correct space group is found to be . A detailed list of refined structural parameters of these compounds is presented for the first time.     

Zwei neue Ammoniakate des Scandiumtrichlorides,ScCl3(NH3) und ScCl3(NH3)2

Two New Ammoniates of Scandium Trichloride, ScCl₃(NH₃) and ScCl₃(NH₃)₂ Reactions of scandium with ammonium chloride in the presence of cupric chloride in sealed copper ampoules yield colorless single crystals of the two new ammoniates of scandium trichloride, ScCl₃(NH₃) und ScCl₃(NH₃)₂. The crystal structures were determined from single crystal data; they both crystallize with the triclinic crystal system. In ScCl₃(NH₃)₂ isolated unsymmetrical dimers of double octahedra, according to [Sc‐mer‐(NH₃)_3/1Cl_1/1Cl_(2/2)×2Sc(NH₃)_1/1Cl_3/1] are the characteristic structural features. The crystal structure of ScCl₃(NH₃) also contains double octahedra, [Sc(NH₃)_2/1Cl_2/1Cl_2/2]₂; these dimers are, however, connected via common edges forming infinite zig‐zag chains according to the formulation [Sc(NH₃)_1/1Cl_1/1Cl_4/2].     

Effect of outer cations and water of crystallization on the radiolytic decomposition of nitrates

The -ray induced decomposition of several inorganic nitrates CsNO₃, TlNO₃, Mg/NO₃/₂.6H₂O, Ca/NO₃/₂.4H₂O, Hg/NO₃/₂, Hg/NO₃/₂.2H₂O, Pb/NO₃/₂ and Al/NO₃/₃.9H₂O has been studied at an absorbed dose of {5 Mrads. G/NO ₂ ^– / is affected by the outer cation and depends mainly on its valency and ionic size. G/NO ₂ ^– / for hydrated mercuric nitrate is always higher as compared to that for the anhydrous mercuric nitrate at various doses. Water of crystallization might provide extra factors to facilitate the decomposition of the hydrated nitrate compared to that for the anhydrous salts. In most cases G/NO ₂ ^– / decreases exponentially with dose but in cases of CsNO₃, Mg/NO₃/₂.6H₂O and Al/NO₃/₃.9H₂O it varies linearly.     

碳纳米管-氧化铝:高抗硫及再生性能的Pt基催化剂载体及在NO_x还原反应中的应用(英文)

通过乙炔在Al2O3上的分解制备碳纳米管-氧化铝(Al2O3-CNTs)载体.采用浸渍法,分别制备了Pt/Ba/Al2O3-CNTs和Pt/Ba/Al2O3催化剂.利用XRD,SEM,TEM,低温N2物理吸附,XPS和in-situ DRIFTS等手段对催化剂的物化性质进行了表征.结果表明,在SO2存在下的NOx还原反应中,Pt/Ba/Al2O3-CNTs比Pt/Ba/Al2O3具有更高的抗SO2性能和再生性能.In-situ DRIFTS表明SO2的存在对NOx储存还原的途径没有影响.     

A Dumbbell Shaped Fullerene Dimer with An Inorganic Linker. Addition of C60 and Tetracyanoethylene to Ir2(CO)2Cl2(Ph2P(CH2)nPPh2)2 (n=5 or 7)

The centrosymmetric dimers, ( ²-C₆₀)₂Ir₂(CO)₂Cl₂(-Ph₂P(CH₂)₇PPh₂)₂ and ( ²-TCNE)₂Ir₂(CO)₂Cl₂(-Ph₂P(CH₂)₅PPh₂)₂, have been prepared by the reactions of C₆₀ with Ir₂(CO)₂Cl₂(-Ph₂P(CH₂)₇PPh₂)₂ and of tetracyanoethylene (TCNE) with Ir₂(CO)₂Cl₂(-Ph₂P(CH₂)₅PPh₂)₂, respectively. The structures of both adducts have been elucidated by single crystal X-ray diffraction studies.     

Enhanced electrochemical performance and mechanism study of AgLi1/3Sn2/3O2 for lithium storage

Herein, AgLi_1/3Sn_2/3O₂ with delafossite structure was prepared by treating the layered compound Li₂SnO₃ with molten AgNO₃ via ion exchange of Li⁺ for Ag⁺. The structure characterization and the electrochemical performance of AgLi_1/3Sn_2/3O₂ was thoroughly investigated. AgLi_1/3Sn_2/3O₂ is found to possess stacking lamellar morphology, which means small electrochemical impedance and so facilitates charge transfer kinetics during the cycling. Compared with Li₂SnO₃, due to the introducing of excellent electrical conductivity of silver, AgLi_1/3Sn_2/3O₂ exhibits improved electrochemical performance in terms of capacity, cycling stability and coulombic efficiency. The results show AgLi_1/3Sn_2/3O₂ presents favorable specific capacity of 339 mAh/g at current density of 200 mA/g after 50 cycles and initial coulombic efficiency of 96%. Ex situ XRD analysis revealed the reaction mechanism of AgLi_1/3Sn_2/3O₂ as an anode for lithium ion batteries.     

Synthesis,characterization and electrochemistry of diiron 1,2-dithiolate complexes with a trans-cinnamate ester

Three diiron 1,2-dithiolate complexes with a trans-cinnamate ester have been characterized. Esterification of [Fe₂(CO)₆{μ-SCH₂CH(CH₂OH)S}] (1) with trans-cinnamic acid in the presence of N,N′-dicyclohexylcarbodiimide and 4-dimethylaminopyridine afforded [Fe₂(CO)₆[μ-SCH₂CH(CH₂O₂CCH?=?CHPh)S}] (2) in 94% yield. Carbonyl substitution of 2 with a monophosphine ligand tris(4-fluorophenyl)phosphine or tris(2-methoxyphenyl)phosphine in the presence of Me₃NO·2H₂O resulted in formation of the corresponding monophosphine-substituted complexes [Fe₂(CO)₅ {P(C₆H₄F-4)₃}{µ-SCH₂CH(CH₂O₂CCH?=?CHPh)S}] (3) and [Fe₂(CO)₅{P (C₆H₄OCH₃-2)₃}{µ-SCH₂CH(CH₂O₂CCH?=?CHPh)S}] (4) in 79% and 84% yields, respectively. Complexes 2-4 were structurally characterized by elemental analysis, spectroscopy and X-ray crystallography. Moreover, electrochemical properties of 2-4 were investigated.