Cu/Sr3Ti2O7的制备及其光催化分解水制氢活性

采用聚合合成法(PCM)合成出层状钙钛矿结构的Sr3Ti2O7, 进而负载Cu 离子, 制成Cu/Sr3Ti2O7催化剂. 以超纯水和甲醇牺牲剂体系的光催化分解反应为探针, 通过检测氢气生成速率评价了催化剂的光催化性能, 并借助光电子能谱(XPS)、X 射线衍射(XRD)分析、紫外-可见漫反射光谱(UV-Vis DRS)等手段对催化剂进行了表征. 实验结果表明, Cu 在催化剂中以多价态存在, Cu+和吸附氧有利于光生电子的转移. Cu/Sr3Ti2O7催化剂较之纯Sr3Ti2O7催化剂活性大大提高, Cu 最佳负载量为1.5%(w). 产氢速率可稳定在550-600 μmol·h-1. 还原过的Cu/Sr3Ti2O7催化剂产氢速率最高可达1140.8 μmol·h-1.     

Low-Temperature Heat Capacities and Thermodynamic Properties of Hydrated Nickel L-Threonate Ni（C4H7O5）2·2H2O（S）

Low-temperature heat capacities of the compound Ni（C4H7O5）2·2H2O（S） have been measured with an auto- mated adiabatic calorimeter. A thermal decomposition or dehydration occurred in 350--369 K. The temperature, the enthalpy and entropy of the dehydration were determined to be （368.141 ±0.095） K, （18.809±0.088） kJ·mol ^-1 and （51.093±0.239） J·K^-1·mol^-1 respertively. The experimental values of the molar heat capacities in the temperature regions of 78-350 and 368-390 K were fitted to two polynomial equations of heat capacities （Cp,m） with the reduced temperatures （X）, [X=f（T）], by a least squares method, respectively. The smoothed molar heat capacities and thermodynamic functions of the compound were calculated on the basis of the fitted polynomials. The smoothed values of the molar heat capacities and fundamental thermodynamic functions of the sample relative to the standard reference temperature 298.15 K were tabulated with an interval of 5 K.     

Preparation and crystal structure of Li6Zr2O7 and Li6Hf2O7

Li₆Zr₂O₇ was obtained by annealing an intimate mixture of LiOH · H₂O and freshly prepared ZrO₂ in a stream of argon. It is monoclinic: C2/c, a = 1 044.5(1), b = 598.9(1), c = 1 020.0(1) pm, β = 100.26(1)°, Z = 4, R = 0.016 for 1 218 F values and 55 variables. The structure is closely related to that of NaCl with an ordered distribution of the metal atoms on the sodium sites while the oxygen atoms occupy seven eighths of the chlorine positions. Li has square pyramidal, Zr octahedral oxygen coordination. The corresponding Hf compound is isotypic: a = 1 040.2(1), b = 596,2(1), c = 1 015.0(1) pm, β = 100.36(1)°. ⁷Li nuclear magnetic resonance spectra of this compound give no indication for a high mobility of the Li⁺ ions.     

Time‐Resolved High and Low Temperature Phase Transitions of the Nanocrystalline Cubic Phase in the Y2O3‐ZrO2 and Fe2O3‐ZrO2 System

The nanocrystalline cubic Phase of zirconia was found to be thermally stabilized by the addition of 2.56 to 17.65 mol % Y₂O₃ (5.0 to 30.0 mol % Y, 95.0 to 70.0 mol % Zr cation content). The cubic phase of yttria stabilized zirconia was prepared by thermal decomposition of the hydroxides at 400°C for 1 hr. 2.56 mol % Y₂O₃‐ZrO₂ was stable up to 800°C in an argon atmosphere. The samples with 4.17 to 17.65 mol % Y₂O₃ were stable to 1200°C and higher. All samples at temperatures between 1450°C to 1700°C were cubic except the sample with 2.56 mol % Y₂O₃ which was tetragonal. The crystallite sizes observed for the cubic phase ranged from 50 to 150 Å at temperatures below 900°C and varied from 600 to 800 nm between 1450°C and 1700°C. Control of furnace atmosphere is the main factor for obtaining the cubic phase of Y‐SZ at higher temperature. Nanocrystalline cubic Fe‐SZ (Iron Stabilized Zirconia) with crystallite sizes from 70 to 137 Å was also prepared at 400°C. It transformed isothermally at temperatures above 800°C to the tetragonal Fe‐SZ and ultimately to the monoclinic phase at 900°C. The addition of up to 30 mol % Fe(III) thermally stabilized the cubic phase above 800°C in argon. Higher mol % resulted in a separation of Fe₂O₃. The nanocrystalline cubic Fe‐SZ containing a minimum 20 mol % Fe (III) was found to have the greatest thermal stability. The particle size was a primary factor in determining cubic or tetragonal formation. The oxidation state of Fe in zirconia remained Fe³⁺. Fe‐SZ lattice parameters and rate of particle growth were observed to decrease with higher iron content. The thermal stability of Fe‐SZ is comparable with that of Ca‐SZ, Mg‐SZ and Mn‐SZ prepared by this method.     

Copper(II)‐Catalyzed Synthesis of N‐Substituted‐3‐amino‐4‐cyano‐isoquinoline‐1(2H)‐ones by the Reaction of N‐Substituted‐2‐iodobenzamides with Malononitrile

A novel Cu(OAc)₂·H₂O catalyzed coupling reaction of N‐substituted‐2‐iodobenzamides with malononitrile to afford N‐substituted‐3‐amino‐4‐cyano‐isoquinoline‐1(2H)‐ones is described. The reaction proceeded in DMSO at 90°C for 5 h in nitrogen without external ligands.     

XANES Spectroscopic Studies of the Phase Transition in Gd2Zr2O7

The structural phase transition from fluorite to pyrochlore and the strength of the coordination bond of Zr–O in Gd₂Zr₂O₇ were investigated by XANES spectra of both O and Zr K‐edge. The energy difference of the O K‐edge absorption spectra at 532 and 536 eV was assigned to the crystal field splitting energy of the 4d orbital (ΔE_4d, t_2g and e_g) of the Zr ion. Also, in the samples prepared at higher temperatures, the 536 eV peak moves slightly to higher energy, whereas the absorption energy of 532 eV peak does not shift. A correlation between ΔE_4d and the strength of interaction between Zr (4d) and O (2p) orbitals has been found. Furthermore, two Zr K‐edge absorptions at 18020 and 18030 eV of Gd₂Zr₂O₇ have been observed; the splitting energy (ΔE), peak intensity ratio (I₁₈₀₃₀/I₁₈₀₂₀), and FWHM of the first derivative of the absorption curve depend on the preparation temperatures. The effect of crystal symmetry and Zr‐O bonding character on the XANES spectral profile was discussed.     

La2M2O7(M=Ti,Zr)多晶粉末的低温水热合成及表征

低温水热合成是水热化学一个活跃的研究方向,在氧化物粉末的合成方面具有潜在的应用价值.La2M2O7(M=Ti,Zr)陶瓷材料的优良特性使其多晶粉末的合成倍受关注[1,2].     

Synthesis of the Coumarins via Pechmann Method in the Presence of Environmentally Friendly Y(NO3)3×6H2O

Several substituted coumarins can be prepared in high yield and purity by direct reaction of β‐keto esters and phenol derivatives in the presence of a catalytic amount Y(NO₃)₃×6H₂O as Lewis acid and at ambient temperature under solvent‐free conditions.     

不同含量Y2O3的ZrO2对Al2O3复合陶瓷热震稳定性的影响

含2% (摩尔分数) Y2O3的ZrO2 (简称TZP(2Y)) 和3% (摩尔分数) Y2O3的ZrO2 (简称PSZ(3Y)) 分别以15%(体积分数)添加到Al2O3基体中, 经1550 ℃真空烧结.实验表明, Al2O3复合材料的性能均高于单相Al2O3陶瓷, 并且Al2O3/PSZ(3Y)的抗热震性优于Al2O3/TZP(2Y). 提高改善复合材料的抗热震性是ZrO2(Y2O3)多种增韧机制的作用. 理论计算表明, Al2O3陶瓷和Al2O3/TZP(2Y), Al2O3/PSZ(3Y)复合材料的断裂功分别为38, 100.8, 126.2 J·m-2. Al2O3/TZP(2Y) 和 Al2O3/PSZ(3Y)复合材料的裂纹萌生阻力是Al2O3陶瓷的1.41倍和1.57倍, 而裂纹扩展阻力是Al2O3陶瓷的1.38倍和1.46倍, 与热震实验残余强度的结果一致.     

New Borate‐citrate: Synthesis,Structure, and Properties of Sr[B(C6H5O7)2](H2O)4·3H2O

Single crystals of Sr[B(C₆H₅O₇)₂](H₂O)₄ · 3H₂O, a new borate‐citrate material, were grown with sizes up to 8 × 6 × 2 mm by slow evaporation of water at room temperature. The structure of Sr[B(C₆H₅O₇)₂](H₂O)₄ · 3H₂O was determined by single‐crystal X‐ray diffraction. It crystallizes in the monoclinic space group P2₁/c, with a = 11.363(3) Å, b = 18.829(4) Å, c = 11.976(3) Å, β = 110.736(3)°, and Z = 4. The SrO₈ dodecahedra, BO₄ tetrahedra and citrate groups are linked together to form chains. The compound was characterized by IR and UV/Vis/NIR transmittance spectroscopy as well as thermal analysis.     

C—H···X (X = N,O, S) intramolecular interaction in 1‐vinyl‐2‐(2′‐heteroaryl)pyrroles as monitored by 1H and 13C NMR spectroscopy

¹H and ¹³C NMR spectroscopy of a series of 1‐vinyl‐2‐(2′‐heteroaryl)‐pyrroles were employed for the analysis of their electronic and spatial structure. The C—H···N intramolecular interaction between the α‐hydrogen of the vinyl group and the pyridine nitrogen, a kind of hydrogen bonding, was detected in 1‐vinyl‐2‐(2′‐pyridyl)pyrrole, which disappeared in its iodide methyl derivative. It was shown that this interaction is stronger than the C—H···O and C—H···S interactions in 1‐vinyl‐2‐(2′‐furyl)‐ and ‐2‐(2′‐thienyl)‐pyrroles. Copyright © 2001 John Wiley & Sons, Ltd.     

Investigations of the local distortions and EPR parameters for Cu2+ in xNa2O‐(30–x)K2O‐70B2O3 (5 ≤ x ≤ 25 mol%) glasses

The local distortions and electron paramagnetic resonance parameters for Cu²⁺ in the mixed alkali borate glasses xNa₂O‐(30–x)K₂O‐70B₂O₃ (5 ≤ x ≤ 25 mol%) are theoretically studied with distinct modifier Na₂O compositions x. Owing to the Jahn–Teller effect, the octahedral [CuO₆]¹⁰⁻ clusters show significant tetragonal elongation ratios p ~19% along the C₄ axis. With the increase of composition x, the cubic field parameter Dq and the orbital reduction factor k exhibit linearly and quasi‐linearly decreasing tendencies, respectively, whereas the relative tetragonal elongation ratio p has quasi‐linearly increasing rule with some fluctuations, leading to the minima of g factors at x = 10 mol%. The composition dependences of the optical spectra and the electron paramagnetic resonance parameters are suitably reproduced by the linear or quasi‐linear relationships of the relevant quantities (i.e., Dq, k, and p) with x. The above composition dependences are analyzed from mixed alkali effect, which brings forward the modifications of the local crystal‐fields and the electronic cloud distribution around Cu²⁺ with the variation of the composition of Na₂O.     

Low Temperature Synthesis and Characterization of Li1.2-y NayV3O8(0≤y≤1.2) from V2O5 Gel

Without overnight heating and stirring,Li1.2V3O8 and its analogs Li1.2-y NayV3O8(0≤y≤1.2) were successfully synthesized by adding mixed solution of LiOH and NaVO3 to V2O5 gel and dehydrating the prepared gel in 150-350℃.The simplicity awards this synthesis process superiority over other low temperature synthesis routes when mass production is concerned.TG-DTA,XRD and TEM experiments were carried out for physical characterization.By galvanostatic charge-discharge and cyclic voltammetry tests,these products showed better electrochemical performance than high temperature products as cathode active materials in secondary lithium batteries.After treatment of Li1.2V3O8 at 250℃,it exhibited a capacity of 350mAh/g when cycled at current rate of about 60 mA/g over the voltage range of 3.8-1.7V vs,Li^ /Li.The influence of partial substitution of Li by Na was also extensively studied.     

Mechanisms for H2O decomposition on the Si(111)‐7 × 7 surface: A DFT cluster model study

The mechanisms for the complete decomposition of water molecules on the Si (111)‐7 × 7 surface were investigated theoretically. The reaction pathways for dissociation of four water molecules over the adatom and rest atom sites were calculated using the density functional theory (DFT) in conjunction with the B3LYP functional. The calculated results demonstrated that the initial O? H bond dissociation from the first H₂O to form the adsorbed OH species is more preferential on the adatom site (Si_a) than the rest atom site (Si_r) of Si (111)‐7 × 7. Four water molecules dissociate successively over the adatom site, backbonds of adatoms which are saturated by OH species can reasonably be the place of insertion of oxygen atoms, yielding a tetrahedral SiO₄ structure with one on top and three inserted oxygen atoms. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2010     

Design,Synthesis, and Evaluation of 3‐((4‐(t‐Butyl)‐2‐(2‐benzylidenehydrazinyl)thiazol‐5‐yl)methyl)quinolin‐2(1H)‐ones as Neuraminidase Inhibitors

A series of novel 3‐((4‐(t‐butyl)‐2‐(2‐benzylidenehydrazinyl)thiazol‐5‐yl)methyl)quinolin‐2(1H)‐ones ( 7a – 7z ) were designed, synthesized and evaluated for their ability of inhibiting neuraminidase (NA) of in?uenza H1N1 virus. Some compounds displayed moderate influenza NA inhibitory activity. Compound 7l with the scaffold of 2‐(2‐(2‐methoxybenzylidene)hydrazinyl)thiazole was the best one, exhibiting moderate NA inhibitory activity with IC₅₀ of 44.66 µmol/L. Structure‐activity relationship showed that compounds with methoxy or hydroxy groups at the ortho position, fluorine and nitro groups at the meta position and chlorine and bromine groups at the para position of phenyl ring were more active. Docking study indicated that compound 7l has important interactions with some key residues (including Asp151, Glu119, Arg292, Tyr406, and Asn347) and binds to 430‐cavity adjacent to NA active site.     

可见光下Fe~（3＋）掺杂对K2La2Ti3O（10）分解水制氢性能的影响

采用溶胶-凝胶法制备了Fe3+掺杂的Fe-K2La2Ti3O10.光催化剂,并通过X射线衍射(XRD)、紫外-可见漫反射(DRS)、X射线光电子能谱(XPS)等技术对其进行了表征和分析,考察了不同掺杂量对K2La2Ti3O10的性质及光催化分解水制氢活性的影响.结果表明,Fe-K2La2Ti3O10.在400-650 nm范围内显示强吸收,光谱响应扩展到可见光区(λ>400 nm),掺杂Fe3+后,K2La2Ti3O10.的可见光区的光催化制氢活性显著提高,掺杂量为nPe/nn=0.04时活性最佳,当催化剂用量为0.1 g,反应液为CH3OH(30 mL)+H2O(90 mL)时,产氢量达到1.92 μmol·h-1,为未掺杂时的4倍.     

Synthesis of (4Z)‐4‐(Arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones by the Reaction of Ethyl (2Z)‐3‐Aryl‐2‐isothiocyanatoprop‐2‐enoates with Organolithium Compounds

A convenient one‐pot method for the preparation of (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones 2 and 3 from ethyl (2Z)‐3‐aryl‐2‐isothiocyanatoprop‐2‐enoates 1 , which can be easily prepared from ethyl 2‐azidoacetate and aromatic aldehydes, has been developed. Thus, these α‐isothiocyanato α,β‐unsaturated esters were treated with organolithium compounds, including lithium enolates of acetates, to provide 5‐substituted (4Z)‐4‐(arylmethylidene)‐5‐ethoxy‐1,3‐oxazolidine‐2‐thiones, 2 , and 2‐[(4Z)‐(4‐arylmethylidene)‐5‐ethoxy‐2‐thioxo‐1,3‐oxazolidin‐5‐yl]acetates, 3 .     

Al掺杂对Li(AlyCo1-y)O2材料结构的影响

报道了在800℃烧结制备的新型锂二次电池正极材料Li(AlyCo_1-y)O₂(y=0,0.11)的X射线衍射结果和由此而揭示的结构演化过程.研究表明,y≤0.5时,材料呈单相,0.6≤y≤0.9时,材料呈两相[Li(AlyCo_1-y)O₂,C-LiAlO₂]共存状态,y=1时,材料又呈单相,为LiAlO₂相.Li(AlyCo_1-y)O₂材料中y值的上限即Al的最大固溶度在0.5左右.在单相区(y≤0.5),随着Al掺杂的增多,Li(AlyCo_1-y)O₂材料晶格结构参数发生变化,a轴缩短,c轴变长,c/a比基本呈线性增加,材料的层状属性更加明显.     

C—H…Cl Hydrogen Bond and π-π Interaction Based Two 3D Supramolecular Architectures of Cu(II) and Co(II) Complexes with Chiral 1,2-Bis(benzimidazol-2-yl) ethane Ligand Containing 2D Grids

合成了两个新的配合物CuLCl₂•2EtOH(1) 和CoLCl₂ (2) [L是( S , S )－1,2－二N－甲基苯并咪唑－1,2－二甲氧基－乙烷],并通过单晶X衍射确定它们的结构。配合物1中,L作为三齿[N, N, O]配体,而配合物2 中,L作为二齿[N, N]配体。这两个配合物共同的结构特点都是通过分子内氢键形成2维的格子结构,然后通过分子间的C－H···Cl型氢键和π–π堆积作用形成3维结构。