Microstructure and Defect Characterization of Nanostructured Ni<Subscript>3</Subscript>Al

Summary.  Nanostructured Ni₃Al was produced by the inert gas condensation and in situ compaction technique and characterized by means of high-resolution transmission electron microscopy (HRTEM), X-ray diffraction, and density measurements. The defect structure was investigated using positron annihilation lifetime spectroscopy (PALS). It is shown that in some samples besides the cubic also the martensitic phase can be present. The defect structure can be divided into three major components: vacancy-like defects in the grain boundaries and nano-voids with a size of 1 nm as seen with PALS, and large pores with sizes up to 8 nm as seen with HRTEM. Furthermore, it is shown that an increasing compaction temperature leads to significantly smaller nano-voids. Received October 5, 2001. Accepted (revised) November 12, 2001     

Ni2P@CoP3核壳纳米球的制备、表征及其用于超级电容器性能

利用水热技术先后获得Ni纳米球和Ni@Co(OH)_2海胆状核壳纳米球前驱体,通过高温煅烧法获得NiO@CoO核壳纳米球,再以次磷酸钠为原料,通过高温磷化法最终获得Ni_2P@CoP_3核壳纳米球。利用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、高角度环形暗场像扫描透射电子显微镜(HAADF-STEM)、X射线粉末衍射仪(XRD)、能谱仪(EDS)及X射线光电子能谱(XPS)对产物的形貌、结构和组成进行表征。采用循环伏安(CV)、恒电流充放电(GCD)以及循环稳定性实验探索了电极材料的电化学性能。结果表明,Ni_2P@CoP_3核壳纳米球的直径约为400 nm,由六方系Ni_2P纳米核和立方相CoP_3纳米壳构成。相比单纯的Ni_2P或CoP_3纳米球,Ni_2P@CoP_3核壳纳米球发挥了复合结构的协同效应,更加有利于电解液的质子传递,促进了赝电容反应,表现出更高的比容量、稳定性和更长的循环寿命。     

Wasserstoff-Adsorption an Ti3Al

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层状Li(Ni1/3Co1/3Mn1/3)O2正极材料的合成与电化学性能研究

采用共沉淀-喷雾造粒法制备前驱体, 于750 ℃在空气中煅烧20 h合成出层状Li(Ni_1/3Co_1/3Mn_1/3)O₂正极材料, 并用XRD, SEM, 粒度分析和电性能测试考察了所得材料结构、形貌及电化学性能. 本层状Li(Ni_1/3Co_1/3Mn_1/3)O₂正极材料具有α-NaFeO₂结构, 六方晶系, R3m空间群, 其晶胞参数为a＝0.2865 nm, c＝1.4238 nm. 当材料分别在2.8～4.2, 2.8～4.5 V间进行充放电时, 其首次放电容量分别为173.5和185.4 mAh•g^－1, 首次充放电效率分别为90%和83.8%, 40次循环后容量保持率分别为96%和84%.     

Density functional calculations of Ni5 and Ni6 clusters

Density functional calculations on the electronic structure and magnetic properties of Ni₅ and Ni₆ clusters are presented in this work. The geometry and spin state of clusters are optimized for several starting symmetries. Moreover, those calculations are followed by a vibrational analysis to discriminate between real minima and saddle-points on the potential energy surface of clusters. Equilibrium geometries, electronic configurations, binding energies, magnetic moments, and harmonic frequencies of stable Ni₅ and Ni₆ clusters are reported.     

Ni2P负载量对Ni2P/Ce-Al2O3催化剂结构及萘加氢性能的影响

采用程序升温还原法制备了一系列Ni₂P/Ce-Al₂O₃催化剂,考察了制备过程中Ni₂P负载量对催化剂结构及萘加氢饱和性能的影响。结果表明,Ni₂P负载量可调控活性组分Ni₂P与载体Ce-Al₂O₃之间的相互作用,进而调变催化剂的比表面积、Ni₂P粒径及催化剂活性位点数量。当Ni₂P负载量（质量分数）为17%时,催化剂具有较大的比表面积（40 m²/g）、较小的Ni₂P粒径（26.3 nm）和最多的活性位点数量（26.7 μmol/g）;同时,该催化剂萘转化率为95%,十氢萘选择性为76%,且活性稳定性良好,这主要归因于催化剂大的比表面积和高的活性位点数量为反应提供了更多的场所。     

Efficient synthesis of ferrocenylenones by Friedel-Crafts acylation with EtAlCl2-Me3Al

Efficient synthesis of ferrocenylenones using a Friedel-Crafts acylation reaction is described. Acryloyl, methacryloyl, crotonoyl, cinnamoyl, and β-methylcrotonoyl chlorides react with ferrocene in the presence of a Lewis acid (EtAlCl₂ or EtAlCl₂-Me₃Al) to give the corresponding ferrocenylenones (acryloyl, methacryloyl, crotonoyl, cinnamoyl, and methylcrotonoylferrocenes) in good isolated yields. Besides ferrocenylenones, chloroactylferrocene is also synthesised by this method.     

镍锌纳米晶铁氧体的络合溶胶-凝胶法合成及表征

利用乙酰丙酮(AcAcH)络合溶胶-凝胶法合成了Ni0.5Zn0.5Fe2O4(NZFO)尖晶石型软磁铁氧体。采用傅里叶变换红外光谱(FTIR)技术研究了Fe、Zn、Ni 3种溶胶中AcAcH与Fe3+、Zn2+、Ni2+的结合形式,通过比较Fe、Zn、Ni溶胶与未添加AcAcH的Fe、Zn、Ni甲醇溶液的红外光谱发现,分别在1 532 cm-1、1 520 cm-1和1 520 cm-1处多了一个吸收峰,说明AcAcH都能与3种离子发生螯合反应。采用X射线衍射(XRD)、高分辨透射电子显微镜(HRTEM)、物性测量系统(PPMS)分别表征NZFO铁氧体的相组成、微结构以及磁性能。XRD测试结果表明,NZFO铁氧体为单一尖晶石相结构;HRTEM透射结果表明,NZFO为片状,大小均匀,尺寸45 nm左右;PPMS研究结果表明,NZFO铁氧体的饱和磁化强度(Ms)和矫顽力(Hc)分别为36 emu.g-1和167 Oe。     

Ni5P4/g-C3N4复合光催化剂的制备及光催化性能

使用尿素、 红磷和氯化镍为原料, 通过一种简单的焙烧方法合成了Ni₅P₄/g-C₃N₄光催化剂. 该催化剂形成的异质结可以降低界面电阻, 有效抑制光生电子-空穴对复合率. 以罗丹明B模拟污染物进行降解测试, 发现3NPC的反应速率常数最高, 几乎是g-C₃N₄的7倍, 并具有最高的光催化产氢能力, 制氢速率高达1013.88 μmol·g^-1·h^-1, 明显高于g-C₃N₄(664.38 μmol·g^-1·h^-1).     

Copolymerization of 4-methylpentene-1 and styrene with TiCl3 and iBu3Al and the copolymer structure

Copolymers of 4-methylpentene-1 and styrene were prepared (TiCl₃-AliBu₃, 70°) and their structure investigated. Monomer reactivity ratios calculated from the copolymer compositions were found to be 3·92 and 0·98. Comparison of the i.r. spectra of copolymers thus prepared and of isotactic homopolymers (poly-4-methylpentene-1 and polystyrene) allowed some estimation of monomer distribution in copolymers of different composition; this estimation for styrene units was based on band intensities at 565, 1084 and 985 cm⁻¹, and for 4-methylpentene-1 units on band intensity at 997 cm ⁻¹. These data show the copolymers of 4-methylpentene-1 and styrene to have random structure, and to be described by statistic relationships corresponding to r₁r₂ ≈ 1. Possible reasons for discrepancies between r₁r₂-values from compositional studies and those obtained from i.r. data are discussed.     

明嘉靖朝北京太庙改建规划方案生成之始末

近年来,基于BiVO_4光阳极的光电催化分解水技术引起人们的关注.我们通过水热-氨化法制备出Ni_3N纳米颗粒,首次将其作为助催化剂修饰到BiVO_4光阳极上光电催化分解水.实验表明, Ni_3N纳米颗粒成功负载到BiVO_4光阳极表面并可有效抑制表面电荷复合以及提高光电催化分解水性能.在1.23 V v. RHE处光电流密度可达3.23mA/cm~2.此外, Ni_3N/BiVO_4光阳极的最大值ABPE值达0.88%,并呈现出良好的稳定性.     

NiO Bulk properties: Initial-state molecular-orbital Ni4O4 and Ni13O14 cluster studies

An intial-state molecular-orbital study of NiO (bunsenite) with cluster models produces lattice and force constants close to bulk values and permits assignment of photoemission and optical charge-transfer absorption bands. It is stressed that shake-up effects complicating electronic spectra are unrelated to mechanical properties and structures.     

A new phase in the system lithium-aluminum: Characterization of orthorhombic Li2Al

Investigation of the Li rich part of the binary Li-Al system revealed the existence of a new phase, orthorhombic Li₂Al, which is isostructural to Li₂Ga and Li₂In. The crystal structure was determined from single crystal X-ray diffraction data (Cmcm, a=4.658(2) Å, b=9.767(4) Å, c=4.490(2) Å, Z=4). Refinement of atomic position site occupancies yielded a composition Li_1.92Al_1.08 (64 at% Li) indicating a small homogeneity range, Li_2−xAl_1+x. Li₂Al is the peritectic decomposition product of the stoichiometric compound Li₉Al₄, which is stable below 270±2 °C. Li₂Al itself decomposes peritectically to Li₃Al₂ and Li rich melt at 335±2 °C. The discovery of Li₂Al (Li_2−xAl_1+x) settles a long standing inconsistency in the Li-Al phase diagram which was based on the assumption that Li₉Al₄ possesses a high temperature modification.     

Li[Ni1/3Mn1/3Co1/3]O2掺杂Mo研究

采用高温固相合成法制备了Li[Ni_(1－x)/3Mn_(1－x)/3Co_(1－x)/3Mo_x]O₂ (x＝0, 0.005, 0.01, 0.02). 对它们进行了XRD, SEM, 循环伏安及充放电容量测试, 结果发现, 掺杂x＝0.01 Mo的样品具有较高的嵌锂容量和良好的循环稳定性, 在20 mA/g放电电流密度和2.3～4.6 V的电压范围内具有211.6 mAh/g的首次放电比容量, 循环50周后放电比容量仍能达到185.9 mAh/g, 容量损失为12.1%.     

Synergetic effect between NiO and Ni3V2O8 in propane oxidative dehydrogenation

The oxidative dehydrogenation (ODH) of propane was investigated on Ni-V-O catalysts in a wide range of vanadium contents (5-40%). The addition of a small amount of vanadium significantly increased the catalytic activity of NiO for oxidative dehydrogenation of propane to propene. The formation of propene has a good correlation with the coexistence of NiO and Ni₃V₂O₈. This result strongly suggests that a synergetic effect exists between them in Ni_XV_1-XO_Y (X = 0.95 to 0.6). The best results were obtained with a high Ni/V ratio (e.g. X = 0.95 to 0.85). The active sites and selective oxygen species are discussed. The influence of the catalyst preparation technique and the redox properties of the catalyst were also examined.     

溶剂热法制备球状Ni3S4及其在超级电容器的应用

应用溶剂热法合成Ni3S4微米球,采用XRD和SEM表征样品物相结构、观察其微观形貌.电化学性能测试表明Ni3S4电极有较好的比电容性能,0.5和4 A.g-1放电电流密度下,其比容量分别为1120.6和433.4 F.g-1;1000周循环充放电后,其容量保持率为89.37%和84.88%.XRD、XPS和CV测试结果表明,其电化学反应机理为Ni(OH)2与NiOOH的相互转化.     

高热稳定性纳米Au/TiO2催化剂的制备与表征

 采用三嵌段共聚物聚乙醚-聚丙醚-聚乙醚EO20PO70EO20 (P123)为有机模板剂合成了介孔TiO2载体,用沉积-沉淀法制得Au/TiO2催化剂. 运用N2 吸附-脱附、 X射线衍射、 X射线光电子能谱和高分辨电镜技术对催化剂的结构与形貌进行了表征. 采用P123模板剂合成的TiO2具有较均匀的介孔结构,孔径集中在6.1 nm附近,负载金后,其介孔结构保持良好,但孔径下降至5.4 nm. 400 ℃焙烧后,介孔TiO2负载的Au催化剂中Au主要以金属态存在. 负载在三种TiO2载体(介孔TiO2、溶胶-凝胶法合成的TiO2和工业TiO2)上的Au晶粒大小和分散度差异较大,其中介孔TiO2载体更有利于金的分散,以该载体制备的催化剂400 ℃焙烧后金的晶粒尺寸在1～5 nm范围内,催化剂显示了很好的CO氧化活性和抗热稳定性,即使在420 ℃焙烧,其室温下CO的转化率也在90%以上. 而溶胶-凝胶法制备的TiO2和工业TiO2负载的纳米金催化剂中,金晶粒尺寸约为10 nm,催化剂的CO氧化活性和抗热稳定性较差.     

Heterometallic Trinuclear Ni2Zn and Ni2Mn Complexes of Macrocyclic Oxamide: Synthesis and Crystal Structures

Two novel heterometallic trinuclear complexes of macrocyclic oxamide [Mn(NiL)2(HBTC)H2O] (1) and [Zn(NiL)2(HBTC)H2O] (2) (NiL, H2L = 2,3-dioxo-5,6,14,15-dibenzo-1,4,8,12-tetraazacyclo-pentadeca-7,13-dien, H3BTC = 1,3,5-benzenetricarboxylic acid) have been solvothermally synthesized and structurally characterized by elemental analysis, IR spectroscopy and single-crystal X-ray diffraction. For 1, the crystals crystallize in the monoclinic system, space group P21/c with a = 11.3595(5), b = 23.1498(11), c = 17.2558(8) and =101.2530(10)°. For 2, the crystals crystallize in the monoclinic system, space group P21/c with a = 11.5214(8), b = 20.6566(14), c = 18.4126(13)  and = 92.6770(10)°. The structures of 1 and 2 have oxamido-bridged trinuclear [NiⅡ2MⅡ] units and consist of two-dimensional supramolecular architectures formed by strong O-H…O intermolecular hydrogen bonds.     

Defect Clusters and Superstructures of ZrDissolved Ni1−xO

Ni_1−xO (x<0.001) powders, pure and mixed with pure ZrO₂or yttria–partially stabilized zirconia (Y-PSZ), were sintered and then annealed at 1573 and 1873 K for up to 300 h to investigate the dopant dependence of defect clustering in the Ni_1−xO lattice. Transmission electron microscopic observations coupled with energy X-ray analysis indicated that the dissolution of Zr⁴⁺(ca. 2.0 mol% with or without co-dopant Y³⁺< 0.3 mol%) but not Ni³⁺caused defect clustering, which was more rapid at 1873 than 1573 K and which preferred to nucleate at interfaces and dislocations. The paracrystalline distribution of defects was found to be nearly 3.5 and 2.5 times the lattice parameter of Ni_1−xO for Zr-doped and (Zr,Y)-codoped Ni_1−xO, respectively. The predominantly dissolved Zr⁴⁺cations, in octahedral sites with charge- and volume-compensating nickel and oxygen vacancies (i.e., Zr^oct□_nO_6−m□_m), could create local domains in which Ni³⁺should be expelled and, thus, in the vicinity the paracrystalline state and then the spinel Ni₃O₄could precipitate in local domains. The spinelloid, a superstructure of spinel with a relatively high Zr⁴⁺content (ca. 3.5 mol%), appeared only for the Ni_1−xO particles located at Y-PSZ grain boundaries.