Electrodeposition mechanism of Ni?Mo?P alloy in the solution of ammoniac citrate

The induced codeposition mechanism of Mo, P and Ni from the solution of ammoniac citrate was studied by means of steady-state polarization, AC impedance and X-ray Photoelectron Spectroscopy (XPS). The result of electrochemical measurements proved that [NiCit(NHs)₂]- is the electro-active species of nickel, though nickel ions exist mainly as [NiCit(NH₃)₃]^? in ammoniac citrate. XPS experiments proved the existence of tetravalent molybdenum corresponding to MoO₂ on the surface of mme deposits. The intermediate product, MoO₂, WM probably reduced to Mo in the alloy deposit by atomic hydrogen adsorbed on the induced metal nickel. The reduction of H₂PO^?₂ occurs through two distinctive steps with PH₃ an an intermediate, which subsequently reacts with atomic hydrogen to form P in the alloy deposit. The electrodeposition mechanism was proposed in this paper.     

从氨性柠檬酸溶液中电沉积Ni-Mo的机理研究

含钼大于约27％（质量分数）Ni－Mo合金，具有较高的耐蚀性，特别是在盐酸和硫酸溶液中，其耐蚀性优于SUS304不锈钢［1］．因此，人们对该种合金的电沉积进行了广泛的研究［1－4］．对合金共沉积机理也作了一定的研究．一般认为，钼不能单独进行电沉积，但它可以同铁族元素共沉积［5］．对钼与铁族元素的共沉积机理，人们已提出了几种假设．一般认为［3］，钼可能是多步还原，即六价钼首先被电化学还原成低价钼化合物，而后由吸附在诱导金属（铁族元素）上的原子氢进一步还原成合金中的零价钼，为了进一步弄清Ni－Mo合金的共沉积机理，本…     

纳米晶镍—钼合金电沉积层的结构与性能

通过控电流沉积制备出纳米晶镍钼合金沉积层,沉积层的ＸＲＤ、ＸＰＳ结果表明,纳米晶镍钼合金沉积层存在较大的晶格畸变,其微晶尺寸为１７ｎｍ,纳米合金各元素的结合能发生了不同程度的位移．在３０％的ＫＯＨ溶液中纳米晶镍钼合金电极对析氢反应表现出较高的电催化活性．电化学交流阻抗谱表明,析氢过程按ＶｏｌｍｅｒＨｅｙｒｏｖｓｋｙ机理进行．     

纳米晶Ni-Mo-Co合金镀层的结构与析氢行为

电沉积;结构;纳米晶Ni-Mo-Co合金镀层的结构与析氢行为     

Studies on Structure and Electrocatalytic Hydrogen Evolution of Nanocrystyalline Ni—Mo—Fe Alloy Electrodeposit Electrodes

Nanocrystalline Ni‐Mo‐Fe alloy deposits were obtained by electrode‐position. The structures of the alloy deposits were analyzed by X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS). The XRD results of nanocrystalline Ni‐Mo‐Fe alloy deposit show that many diffraction lines disappear, and that there is only one diffraction peak at 44.0°. The XPS results of nanocrystalline Ni‐Mo‐Fe alloy deposits indicate that the nickel, molybdenum and iron of the deposits exist in metallic state, and that the binding energy of the alloyed elements increases to some extent. The nanocrystalline Ni‐Mo‐Fe alloy deposit electrode may offer better electrocatalytic activity than the polycrystalline nickel electrode and the nanocrystalline Ni‐Mo alloy electrode. The electrochemical impedance spectra from the nanocrystalline Ni‐Mo‐Fe alloy electrode indicate that hydrogen evolution in 30% (m/m) KOH at lower overpotential is in accordance with the Vohner‐Tafel mechanism, but with the Vohner‐Heyrovsky mechanism at higher overpotential.     

Ni-Mo合金电沉积层织构及形成机理

在组成为：０．２２ｍｏｌ／Ｌ硫酸镍、０．０６ｍｏｌ／Ｌ钼酸钠和０．３ｍｏｌ／Ｌ柠檬酸钠的溶液,于纯铜片上采用恒电流沉积,所得Ｎｉ－Ｍｏ合金沉积层经Ｘ射线衍射测定,结果表明在温度为２５℃～５０℃,电流密度为１０ｍＡ·ｃｍ－２～３０ｍＡ·ｃｍ－２范围,Ｎｉ－Ｍｏ合金沉积层表现为（１１１）择优取向．循环伏安和电位阶跃实验表明镍钼合金电结晶过程按照连续成核和三维生长方式进行．Ｎｉ－Ｍｏ合金电沉积过程的电化学交流阻抗谱表明Ｎｉ－Ｍｏ共沉积过程经历了吸附中间产物步骤,由于吸附态物种氢氧化镍和钼的氧化物将阻化晶粒（１１１）晶面的生长,从而使镍钼沉积层表现为（１１１）择优取向．     

Ni-Mo-B非晶态合金纳米颗粒的抗氧化性能研究

在水溶液体系中用化学还原法制备Ni-B和Ni-Mo-B非晶态合金纳米颗粒.SEM测试表明,样品的颗粒形貌呈球形或类球形,平均粒径约10nm.XPS分析结果表明,Ni-Mo-B非晶态合金中钼元素主要以氧化态形成于合金的表面,并导致合金表面合金化硼原子浓度显著增加,氧化态硼（B3＋）的原子浓度显著减少,氧的原子浓度明显减少,合金化镍的原子浓度显著增加,氧化态镍（Ni3＋）的原子浓度显著减少.因此,Ni-Mo-B合金的抗氧化性能显著高于Ni-B合金.XPS谱图分析还表明,在Ni-B和Ni-Mo-B非晶态合金中,存在Ni和B的合金化物Ni2B,其中B失去部分电子,而Ni则富余电子.Ni2B的氧化产生副产物Ni2O3和B2O3.     

Dimeric dioxomolybdenum(VI) and oxomolybdenum(V) complexes with citrate at very low pH and neutral conditions

A novel dimeric dioxomolybdenum(VI) citrate complex, K[(MoO2)2-(OH)(H2cit)2].4H2O (1), with weak coordination of beta-carboxylic acid groups and the first structural example of an oxomolybdenum(V) citrate complex, (NH4)6[Mo2O4(cit)2].3H2O (2) (H4cit = citric acid), are isolated in a very acidic solution (pH 0.5-1.0) and neutral conditions (pH 7.0-8.0), respectively. Complex 1 displays strong double hydrogen bonds through beta-carboxyl and beta-carboxylic acid groups [2.621(9) A]. Transformations of the dimeric molybdenum(VI) citrate show that protonation of a carboxyl group will weaken the coordination of molybdenum(VI) citrate. There are obvious dissociations of molybdenum(VI/V) citrate complexes based on 13C NMR observations in solution.     

甲烷无氧脱氢芳构化催化剂Mo/HZSM-5的研究

催化剂Ｍｏ／ＨＺＳＭ－５在甲烷地氧脱氢芳构化反应中表现出很高的活性，用ＸＲＤ，ＢＥＴ经表面，ＮＨ３－ＴＰＤ及ＴＰＲ等手段，对不抽提前后催化剂上的活性ｏ的种进行了研究，ＸＲＤ结果表明，Ｍｏ物种高度分散于筛表面，随着Ｍｏ担载量的提高，ＢＥＴ比表面积有所下降；但氨水抽提后，比表面积有很大程度的恢复，ＮＨ３－ＴＰＤ结果表明，Ｍｏ物种优先占据分子筛中的强酸位。ＴＰＲ结果显示出有ＭｏＯ３晶相存在的催化剂较易被     

MoO3/TiO2-Al2O3对H2S吸附的XPS研究

应用ＸＰＳ对ＭｏＯ３／ＴｉＯ２－Ａｌ２Ｏ３体系的ＭｏＯ３在ＴｉＯ２－Ａｌ２Ｏ３载体上的存在状态及其对Ｈ２Ｓ的吸附和脱附性能进行了表征，结果表明：ＭｏＯ３在ＴｉＯ２－Ａｌ２Ｏ３表面存在分散状态的不同，这导致了对Ｈ２Ｓ吸附性能的不同，在相同的条件下，吸附剂的０．１５ｇＭｏＯ３／ｇＴｉＯ２－Ａｌ２Ｏ３时具有最大载硫量，且随吸附温度的升高载硫量也增加，达饱和对Ｓ／Ｍｏ原子比接近１，较好的氧化脱附温度为１５     

Ni(3)(Mo(2)O(8))(XO(3)) (X = Se, Te): the first nickel selenite- and tellurite-containing Mo4 clusters

Two new nickel(II) molybdenum(VI) selenium(IV) and tellurium(IV) oxides generally formulated as Ni3(Mo2O8)(XO3) (X = Se, Te) have been synthesized by solid-state reactions of NiO, MoO3, and SeO2 (or TeO2). Both compounds feature 3D network structures built of [Mo4O16]8- tetranuclear cluster units and 2D nickel(II) selenite or tellurite layers. The nickel(II) selenite layer in Ni3(Mo2O8)(SeO3) is formed by [Ni6O22]32- hexanuclear clusters interconnected by selenite groups whereas the thick nickel(II) tellurite layer in Ni3(Mo2O8)(TeO3) is constructed by corrugated nickel(II) oxide chains bridged by the tellurite groups. The results of magnetic property measurements indicate that there are considerable ferromagnetic interactions between nickel(II) centers in both compounds. Their optical properties and band structures have been also studied.     

Dioxomolybdenum(VI) Complexes with New Enantiomerically Pure Amino Diol Ligands

(R)-Phenylglycinol is shown to be an efficient building block for the synthesis of chiral amino diols in pure diastereomeric form by epoxide ring-opening reactions. The reaction with rac-trans-stilbene oxide gives [HOCH(2)-(R)-PhCH]NH[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-HNO(2)H(2)] in 32% yield, which can be methylated at nitrogen to give enantiomerically pure [HOCH(2)-(R)-PhCH]NCH(3)[(S)-PhCH-(R)-PhCHOH] [2(R)-3(R)-4(S)-MeNO(2)H(2)]. These amino diol ligands have been used to prepare chiral dioxomolybdenyl complexes of the formula N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) (1) and N(R)-2(R)-3(R)-4(S)-(MeNO(2))MoO(2) (2). The absolute configuration at each stereocenter in the Mo(VI) complexes has been established by (1)H NOESY spectroscopy. The configuration determined for 1 has been confirmed by an X-ray analysis. Crystal data: orthorhombic P2(1)2(1)2(1), a =7.620(3), b = 13.589(2), c = 20.339(3) ?, Z = 4, R = 0.0336. The structure consists of a polymeric chain of N(R)-2(R)-3(R)-4(S)-(HNO(2))MoO(2) molecules connected through unsymmetrical Mo=O --> Mo bridges. Each metal center is coordinated in a distorted octahedral geometry by a cis dioxo unit and by two trans alkoxo atoms. The coordination polyhedron is completed by a nitrogen atom and by a bridging oxo oxygen atom from an adjacent molecule. Compound 2 catalyzes the oxidation of PPh(3) to OPPh(3) by DMSO through a mechanism that involves the intermediacy of a Mo(IV) species.     

电沉积Ni—Mo—P合金镀层在NaCl溶液中的腐蚀特性

用失重法，阳极率曲线，Ｘ－光电子能谱（ＸＰＳ）以及俄歇电子能谱（ＡＥＳ）研究了电沉积Ｎｉ－Ｍｏ－Ｐ合金镀层在５％ＮａＣｌ溶液中的腐蚀特性，非晶态Ｎｉ－Ｍｏ－Ｐ合金镀层比晶态Ｎｉ－Ｍｏ－Ｐ合金镀层有较低的腐蚀速度阳极极化曲线表明，Ｎｉ－Ｍｏ－Ｐ合金镀层中，镍的摩尔分数国０．７１９～０．８６８时，随镀层中磷含量的增加，腐蚀电位正移，而活化区的峰电流随镀层中钼含量的增加而增加，磷含量的活化区的峰电流以及     

Crystal structures and 77Se NMR spectra of molybdenum(IV) areneselenolates having intramolecular NH...Se hydrogen bonds

Salts of the monooxomolybdenum(IV,V) areneselenolates having intramolecular NH...Se hydrogen bonds, [Mo(IV)O(Se-2-RCONHC6H4)4]2- (R = t-Bu, CH3, CF3) and [Mo(V)O(Se-2-t-BuCONHC6H4)4]-, were synthesized and characterized by 1H nuclear magnetic resonance (NMR), 77Se NMR, electron spin resonance (ESR), UV-visible spectra, X-ray analysis, and electrochemical measurements. 77Se-1H correlated spectroscopy (COSY) indicated a significant correlation between amide 1H and selenolate 77Se atoms through an NH...Se hydrogen bond with 1J(77Se-1H) = 5.4 Hz coupling. The hydrogen bonds contribute to the positive shift in the Mo(V)/Mo(IV) redox potential. In the crystal structure of (PPh4)2[Mo(IV)O(Se-2-CH3CONHC6H4)4], an NH...O=Mo hydrogen bond was found. Ab inito calculations support the presence of intramolecular NH...O=Mo and NH...Se hydrogen bonds.     

Dispersion and Structure Studies of Molybdenum Oxide on Anatase TiO2

X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure (EXAFS) were used to characterize the structure of the mixture of molybdenum oxide and anatase calcined at 723 K. The resuits indicate that molybdenum oxide can disperse onto the surface of anatase (TiO2) and the dispersion threshold is 11.2 mg in per gram of MoO3 or 4.8 Mo atoms/nm^2 TiO2. When the coment of MoO3 is below the dispersion threshold, MoO3 species is in highly dispersed state interacting strongly with TiO2 support and in discrete tetrahedral coordination. [MoO4], on the surface of TiO2. When the MoO3 loading is above this value, MoO3 exists in both dispersed phase and crystalline phase. MoO3 in dispersed phase is still a discrete [MoO4] tetrahedron; MoO3 in crystal phase is in octahedral coordination.     

Directed synthesis of noncentrosymmetric molybdates using composition space analysis

A systematic investigation of the factors governing the reaction product composition, hydrogen bonding, and symmetry was conducted in the MoO3/3-aminoquinuclidine/H2O system. Composition space analysis was performed through 36 individual reactions under mild hydrothermal conditions using racemic 3-aminoquinuclidine. Single crystals of three new compounds, [C7H16N2][Mo3O10] x H2O, [C7H16N2]2[Mo8O26] x H2O, and [C7H16N2]2[Mo8O26] x 4 H2O, were grown. The relative phase stabilities for these products are dependent upon the reactant mole fractions in the initial reaction gel. This phase stability information was used to direct the synthesis of two new noncentrosymmetric compounds, using either (S)-(-)-3-aminoquinuclidine dihydrochloride or (R)-(+)-3-aminoquinuclidine dihydrochloride. [(R)-C7H16N2]2[Mo8O26] and [(S)-C7H16N2]2[Mo8O26] both crystallize in the noncentrosymmetric space group P2(1) (No. 4), which has the polar crystal class 2 (C2). The second-harmonic generation activities were measured on sieved powders. The structure-directing properties of the molybdate components in each compound were determined using bond valence sums. The structures of all five compounds were determined using single-crystal X-ray diffraction.     

[C6N2H18]2[Mo5O15(HPO4)2]·H2O的水热合成与结构表征

通过水热法合成了一个新化合物[C6N2H18]2[Mo5O15(HPO4)2]·H2O,并通过IR光谱、ICP、元素分析、差热与热重分析和X射线单晶衍射分析等手段进行了表征.结果表明,晶体属三方晶系,P3(2)21空间群,a=1.1231(1)nm,c=2.2802(5)nm,V=2.4911(7)nm3,Dx=2.835Mg/m3,Z=6,最后的一致性因子R=0.0227,wR=0.0675.阴离子中Mo5O15构成一环状结构,2个HPO4一个连在环的下方,一个连在环的上方,形成类似于“飞碟”状的结构,阳离子为2个质子化的四甲基乙二胺.     

Molybdenum(V) on an oxide string. Formation and solution stability of the linear complex (mu-trans-dioxo(tetraphenylporphyrinato)molybdenato(V))- bis(oxo(tetraphenylporphyrinato)molybdenum(V)) perchlorate

The unusual linear trinuclear complex [Mo3O4(TPP)3]+ is formed in solution upon the reaction of [MoO(TPP)-(OClO3)] with [[MoO(TPP)]2O], and an equilibrium between [Mo3O4(TPP)3]+ and its constituent species is rapidly established. Spectrophotometric experiments suggest that [Mo3O4(TPP)3]+ is the predominant species found in solutions resulting from the mixture of [MoO(TPP)(OClO3)] and [[MoO(TPP)]2O], and its formation is strongly favored (log K = 5.5 +/- 0.5 M-1). No evidence of higher oligomers has been observed. A mechanism for the formation of [Mo3O4(TPP)3]+ by the controlled hydrolysis of [MoO(TPP)(OClO3)] is proposed.     

Hydrothermal Synthesis and Structure of a Novel Binuclear Molybdenum Complex with Oxalate Ligand,(enH2){NH4[Co(en)3][Mo2O7(C2O4)]}2·2H2O

The title complex (enH2){NH4[Co(en)3][Mo2O7(C2O4)]}2·2H2O (C18H70Co2Mo4- N16O24, Mr = 1396.52) was obtained under hydrothermal conditions and its crystal structure has been determined by single-crystal X-ray diffraction. It crystallizes in the monoclinic system, space group P21/c with a = 17.8023(8), b = 7.7527(4), c = 16.9781(4)A,β= 103.878(7)°, V = 2274.8(2) A3, Dc = 2.039 g/cm3, Z = 2,μ(MoKα) = 1.878 mm-1 and F(000) = 1408. The final R = 0.0410 and Wr = 0.1070 for 4065 observed reflections with I≥2σ(I). The crystal structure is composed of bi- nuclear [Mo2O7(C2O4)]4- anions, complex [Co(en)3]2+ cations, protonated ethylenediamine cations, ammonium cations and crystal water molecules, which are held together into a three-dimensional network via hydrogen-bonding interactions. The binuclear structure of [Mo2O7(C2O4)]4- consist of one MoO4 and one MoO6 octahedra through sharing a bridging oxygen atom, where the oxalate ligand acts as a bidentate ligand coordinating to the octahedral molybdenum atom though two deprotonated corboxylate groups.     

Photoreductive self-assembly from [Mo7O24]6- to carboxylates-coordinated {Mo142} Mo-blue nanoring in the presence of carboxylic acids

The primary steps of the photoredox reaction between [Mo7O24]6- and carboxylic acid electron (and proton) donors in aqueous solutions are investigated by the chemically induced dynamic electron spin polarization (CIDEP) spectroscopy. The excitation of the O-->Mo ligand-to-metal charge-transfer (LMCT) bands of [Mo7O24]6- in the presence of CH3CO2H induces the emissive electron spin polarization (ESP) of *CH2CO2 and *CH3 radicals with an accompanying formation of the one-electron reduced species [Mo7O23(OH)]6-, which is demonstrated by the triplet mechanism involving the O --> Mo LMCT triplet states. The prolonged photolysis of the solution containing [Mo7O24]6- and CH3CO2H at pH = 3.4 leads to the formation of the acetate/propionate-coordinated {Mo142} Mo-blue nanoring, [MoV28MoV(I)114O429H10(H2O)(49)(CH3)CO2 triple bond Ac5(C2H5CO2 triple bond Pr)]30- (1a) through the formation of the cis-configured dimeric dehydrative condensation to two-electron reduced Mo-blue [(Mo7O23)2]10- ({Mo14}). 1a is isolated as a [NH4]+/[Me3NH]+-mixed salt which is formulated as [NH4]27[Me3NH]3[Mo(V)28Mo(VI)114O429H10(H2O)49(CH3CO2)5(C2H5CO2)].150 +/- 10H2O (1) by results of elementary analysis, single-crystal X-ray analysis, 1H NMR, IR, and UV/Vis measurements, and manganometric redox titration. Based on the building-block sequence of for 1a, the bottom-up processes from [Mo7O24]6- to the {Mo142} ring in the coexistence of beta-[Mo8O26]4- are discussed by (i) the stabilization of the molecular curvature of {Mo14} through both the intramolecular transfer of monomolybdates and the intermolecular transfer of monomolybdates as degradation fragments of beta-[Mo8O26]4-, to yield {Mo21} and {Mo20} building blocks, (ii) the outer-ring formation resulting from seven successive two-electron-photoreductive condensations among {Mo21} and {Mo20}, and (iii) inner-ring formation resulting from eight successive dehydrative condensations between monomolybdate linkers attached to the neighboring head Mo sites.