TG Study of the Dispersion Threshold of Mn2O3 on γ-Al2O3

Mn₂O₃/-Al₂O₃ catalysts were prepared by the impregnation method, and the maximum monolayer dispersion capacity or dispersion threshold value of Mn₂O₃ on the surface of -Al₂O₃ was determined to be 13.08% from the decomposition mass loss of supported Mn(NO₃)₂ in the monolayer state. This was compared with the values estimated from a close-packed monolayer model and an interaction model. It was confirmed that the high activities and selectivities of the catalysts for benzoic acid hydrogenation to benzaldehyde are due to the monolayer dispersion of the Mn₂O₃ on the surface of -Al₂O₃.This revised version was published online in November 2005 with corrections to the Cover Date.     

Preparation of Mn3O4 Nanofibres via An Electrospinning Technique

Thin PVA/manganese acetate composite fibres were prepared by using sol-gel processing and electrospinning technique.After calcinations of the above precursor fibres,Mn3O4 nanofibres with a diameter of 50-200 nm could be successfully obtained.The fibres were characterized by SEM,FT-IR,XRD.The results showed that the crystalline phase and morphology of nanofibres were largely influenced by the calcination temperature.     

Holographic Storage Properties of In：Fe：Mn：LiNbO3 Crystals

In:Fe:Mn:LiNbO3(LN) crystals were grown in air atmosphere by Czochralski method with different concentration of In (0,1,2,3 mol%) in the melts,while the contents of Fe2O3 and MnO were 0.1 and 0.5 mol%,respectively. The location of doping ions was analyzed by Ultraviolet-visible absorption spectra and differential thermal analysis. The diffraction efficiency (η),writing time (τw) and erasure time (τe) of the crystals were measured by two-beam coupling experiment. The dynamic range and photorefractive sensitivity have also been calculated. The results showed that with the increase of In ions in the melt,the absorption edge of In:Fe:Mn:LN crystal shifts to the violet firstly and then makes the Einstein shift,the Curie temperature of crystal increases firstly and then decreases,the storage ratio speeds up,diffraction efficiency decreases,and dynamic range and photorefractive sensitivity increase. The mechanism of holographic storage properties of In:Fe: Mn:LN crystal with different doping concentration of In3+ was investigated,suggesting the In: Fe:Mn:LN crystals are excellent holographic storage materiel with better synthetical properties than Fe:Mn:LN crystals.     

Synthesis of Mn3O4 Nanorods by Solid-State Thermal Decomposition of Manganese(III) Schiff Base Complex [Mn(Brsal-mepn)(μ1,3-N3)]n

Hausmannite Mn₃O₄ nanorods were successfully prepared via solid-state thermal decomposition route with manganese(III) Schiff base complex [Mn(Brsal-mepn)(μ_1,3-N₃)]_n as manganese source in air at 400 °C for 4 h. Powder X-ray diffraction, Fourier transform infrared spectrometry and scanning electron microscopy were used to characterize Mn₃O₄ nanoparticles. These results confirm that the resulting manganese oxide was pure single-phase Mn₃O₄ nanoparticles. Using the present method, Mn₃O₄ nanorods can be product without expensive organic solvent and complicated equipment.     

Charge storage mechanism of MOF-derived Mn2O3 as high performance cathode of aqueous zinc-ion batteries

Aqueous Zinc-ion batteries(ZIB) are attracting immense attention because of their merits of excellent safety and quite cheap properties compared with lithium-ion batteries(LIB).Manganese oxide is one of the most important cathode materials of ZIB.In this paper,α-Mn2O3 used as cathode of ZIB is synthesized via Metal-Organic Framework(MOF)-derived method,which delivers a high specific capacity of225 mAh g^-1 at 0.05 A g^-1 and 92.7 mAh g^-1 after 1700 cycles at 2 A g^-1.The charge storage mechanism of α-Mn2O3 cathode is found to greatly depend on the discharge current density.At lower current density discharging,the H+ and Zn2+ are successively intercalated into the α-Mn2O3 before and after the "turning point" of discharge voltage and their discharging products present obviously different morphologies changing from flower-like to large plate-like products.At a higher current density,the low-voltage plateau after the turning point disappears due to the decrease of amount of Zn2+ intercalation and the H+intercalation is dominated in α-Mn2 O3.This study provides significant understanding for future design and research of high-performance Mn-based cathodes of ZIB.     

Synthesis and Crystal Structure of Mn(phen)(CF3COO)(H2O)3·NO3

The mononuclear manganese complex Mn(phen)(CF3COO)(H2O)3(NO3 (C14H14O8N3F3Mn) has been synthesized, where phen = 1,10-phenanthroline. The molecular and crystal structures were determined by single-crystal X-ray diffraction. The crystal is of monoclinic, space group P21/c with a = 8.8550(3), b = 10.6529(3), c = 19.8763(2) A, β = 97.762(2)o, V = 1857.78(8) A3, Z = 4, Mr = 464.22, Dc = 1.660 g/cm3, μ = 0.789 mm-1, F(000) = 940, T = 293(2) K, R = 0.0764 and wR = 0.2441 for 1995 observed reflections with I > 2σ(I). In the crystal the manganese atom is six-coordinated by two chelated nitrogen atoms from phenanthroline, three oxygen atoms from water molecules and one oxygen atom from trifluoroacetate, completing an octahedral geometry.     

Behavior of Mn3+ ions in four-layered hexagonal (Sr1−x−yLaxBay)MnO3

Stoichiometric four-layered hexagonal (4H) (Sr_1?x?yBa_xLa_y)MnO₃ was synthesized using a standard ceramic technique. Rietveld analysis at room temperature indicated that the Mn–O(1) distance increased and the Mn–O(2) distance decreased with the increase in x. The samples were n-type semiconductors and exhibited hopping conductivity in a small-polaron model below 533 K. The Mn³⁺ ion acted as a donor and the electron transfer became active through the Mn³⁺–O–Mn⁴⁺ path. The samples were antiferromagnetic and the Néel temperature (T_N) was constant regardless of y when x was fixed to 0.3, whereas T_N shifted to a high temperature when y was fixed to 0.02. The face-sharing Mn³⁺–O(2)–Mn⁴⁺ interaction strengthened as the Mn–O(2) distance decreased, and T_N shifted to a high temperature as a result.     

Magnetotransport properties of Mo substituted La0.7Ca0.3Mn1−xMoxO3 perovskites

We studied the effects of Mo substitution on the structural, transport, and magnetic properties of the La_0.7Ca_0.3Mn_1−xMo_xO₃ (x ≤ 0.1) samples. Powder X-ray diffraction analysis reveals that the samples studied crystallize in the orthorhombic structure with space group Pbnm. Both particle size and morphology change significantly as the Mo content x varies. The metal-insulator transition temperature (T_MI) and Curie temperature (T_C) decrease monotonically as x increases. Magnetization data reveal that long-range FM ordering persists in all samples and the saturation moment decreases linearly as x increases. The smaller depression rate of dT_C/dx observed is mainly ascribed to the increased amount of Mn²⁺ ions with Mo doping, which opens the FM coupling between Mn²⁺–O–Mn³⁺ in the samples.     

Synthesis and Crystal Structure of Mn(phen)(CF_3COO)(H_2O)_3·NO_3

1 INTRODUCTION The manganese(II) ion is a biologically essential element. Knowledge of its importance is increasing as more and more enzymes are found to contain manganese ions at the active center[1, 2]. The X-ray crystallographic structures of a consi…     

Mn3+/Mn2+氧化还原体系的旋转圆盘电极法性能

氧化还原液流电池的独特性能受到关注[1～4]。本文综合运用循环伏安法,旋转圆盘电极法研究锰离子浓度较高(0 25～0 35mol·L-1、转速范围较宽(400～4200rpm)、同时考虑过电位的条件下Mn(Ⅲ)/Mn(Ⅱ)电对在RDE铂盘电极上的电极过程动力学并确定有关的动力学参数,了解其影响因素,为该电对作为氧化还原液流电池正极活性材料提供动力学依据。1　实验部分铂电极使用前在铬酸洗液中浸10min,水冲洗干净,蒸馏水淋洗,然后在6 3mol·L-1H2SO4中超声清洗10min,再用CHI660电化学工作站(美国CH仪器公司)控制,以0 05V/s的扫速在-1 0～1 2V之间扫…     

Energetics of the reaction Mn(H)(CO)→Mn(HCO)

Large basis set ab initio Hartree-Fock calculations of the energetics of the model reaction Mn (H)(CO)→Mn(HCO) are reported. The use of polarization functions in the ligand atom basis sets has a profound effect upon the energetics of this isomerization reaction.     

Back cover: Mn2+ or Mn3+? Investigating transition metal dissolution of manganese species in lithium ion battery electrolytes by capillary electrophoresis

A new CE method with ultraviolet–visible detection was developed in this study to investigate manganese dissolution in lithium ion battery electrolytes. The aqueous running buffer based on diphosphate showed excellent stabilization of labile Mn³⁺, even under electrophoretic conditions. The method was optimized regarding the concentration of diphosphate and modifier to obtain suitable signals for quantification. Additionally, the finally obtained method was applied on carbonate-based electrolytes samples. Dissolution experiments of the cathode material LiNi_0.5Mn_1.5O₄ (lithium nickel manganese oxide [LNMO]) in aqueous diphosphate buffer at defined pH were performed to investigate the effect of a transition metal-ion-scavenger on the oxidation state of dissolved manganese. Quantification of both Mn species revealed the formation of mainly Mn³⁺, which can be attributed to a comproportionation reaction of dissolved and complexed Mn²⁺ with Mn⁴⁺ at the surface of the LNMO structure. It was also shown that the formation of Mn³⁺ increased with lower pH. In contrast, dissolution experiments of LNMO in carbonate-based electrolytes containing LIPF₆ showed only dissolution of Mn²⁺.     

Fe Promotion Effect in Mn/USY for Low-temperature Selective Catalytic Reduction of NO with NH3

SCR of NO with NH3 is considered to be the most effective process for the treatment of stack gases from stationary sources1. The commercial catalysts for NH3-SCR are V2O5/TiO2 (anatase) promoted with either WO3 or MoO32-5. Although the vanadium- based cat…     

尖晶石型四氧化三锰中 Mn2+、Mn3+、Mn4+的测定方法和离子分布的研究

采用选择性溶解法和计算法结合的方法,测定了四氧化三锰中Ｍｎ＾２＋、Ｍｎ＾３＋、Ｍｎ＾４＋的含量,求出了四氧化三锰中的锰氧摩尔比和三种不同价态的锰离子在尖晶石中的离子分布式,进而确定其结构。分析结果与ＸＲＤ谱图吻合。     

Synthesis and Crystal Structure of a Mn(Ⅱ) Complex with Thiosemicarbazone Derivative of Pyridine-3-carbaldehyde Showing Unusual Coordination Mode of Tridentate Thiosemicarbazone

The title complex Mn(HL)4(NCS)2(CH3CH2OH)2 has been achieved via selfassembly by incorporating manganese(Ⅱ) into pyridine-3-carbaldehyde thiosemicarbazonate ligand,and characterized by elemental analysis and single-crystal X-ray diffraction study. The crystal crystallizes in triclinic, space group P1 with a = 8.896(2), b = 9.530(2), c = 14.520(4) (A), α =87.035(4), β= 88.112(4), γ= 69.434(4)°, V= 1150.9(5) (A)3, Z = 1, Mr = 984.17, Dc = 1.420 g/cm3,μ(MoKα) = 0.612 mm-1, F(000) = 511, the final R = 0.0574 and wR = 0.1547 for 2855 observed reflections with I ＞ 2σ(I). The complex contains one six-coordinated manganese ion connected by two thiosemicarbazide ligands, in which the thiosemicarbazone ligand acts as a monodentate ligand and coordinates to the center metal atoms via the pyridyl nitrogen atoms, two ethanol molecules and two isothiocyanic anions to give rise to a mononuclear structure. The coordination of a potentially tridentate thiosemicarbazone in manganese(Ⅱ) complex without using its sulfur and imine nitrogen sites is unusual. Hydrogen bonds existing in the complex link the different components to stabilize the crystal structure.     

Synthesis and Crystal Structure of a Mn(II) Complex with Thiosemicarbazone Derivative of Pyridine-3-carbaldehyde Showing Unusual Coordination Mode of Tridentate Thiosemicarbazone

1 INTRODUCTION Heterocyclic thiosemicarbazones as well as their metal complexes have been attracting considerable interest due to their biological activities, such as antiviral, antibacterial, antimalarial, antifungal, and antitumoral activities[1～5]. This prompted us to carry out structural studies of these complexes to provide a basis for understanding their behaviors in living systems. Although quite a number of investigations on the 2-heterocyclic thiosemicarbazones have ap- peared[6…     

Application of Mn(Ⅱ) as a Mimetic Enzyme of Horseradish Peroxidase

HRP is a most commonly used enzyme in H2O2 and glucose detection1, owing to its 2strong activity and quite good selectivity. However, natural HRP has manyshortcomings, such as its expensiveness and instability; the experimental conditions andstorage environment are inconvenient. Therefore, the search for a replacement3-6 forHRP has become an important and interesting work. This paper describes a catalytic spectrophotometry method for the determination ofH2O2 based on …     

Effect of LiNi1/2Mn1/2O2 coating on the electrochemical performance of Li–Mn spinel

Lithium nickel manganese oxide (LiNi_1/2Mn_1/2O₂) was coated on spinel lithium manganese oxide (LiMn₂O₄) by a sol–gel process in an attempt to improve the high temperature cycling performance. The ratio of the coating sol to LiMn₂O₄ was adjusted to determine the relationship between the coating thickness and electrochemical performance. The crystal structure and morphology of the samples were examined by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The charge and discharge characteristics, including cyclability and electrochemical properties of the bare and the coated LiMn₂O₄, were measured and compared. The results showed that a LiNi_1/2Mn_1/2O₂ coating on LiMn₂O₄ improves the rate capability at room temperature, and the cyclability at high temperatures.     

Preparation of Mn2O3 catalyst with core–shell structure via spray pyrolysis assisted with glucose

A novel core–shell Mn₂O₃ catalyst is obtained by facile spray pyrolysis assisted with glucose acting as a structure-directing agent. The detail characterizations include X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption/desorption isotherms, and the thermogravimetric method (TG/DTA). In the probe test of the aqueous degradation of methylene blue (MB), the high catalytic peroxidization activity of core–shell Mn₂O₃ catalyst, compared to the commercial Mn₂O₃, is attributed to the high crystallization of α-Mn₂O₃, the large surface area that resulted from the core–shell structure with porous architecture, and the special core–shell structure that acted as a micro-reactor.