基于密度泛函理论下H_2S在单原子催化剂V/Ti_2CO_2上的分解机理研究

解析工业脱硫气中硫化氢与催化剂的相互作用机制及其分解机理对于开发处理H_2S气体的催化剂具有重要意义。本研究采用密度泛函理论计算方法研究了H_2S分子在单原子催化剂(SACs,Ti和V原子负载的单层MXene-Ti_2CO_2)表面上的吸附和催化解离行为。分波态密度(PDOS)、电荷分析以及差分电荷密度的结果表明:单原子Ti和V的负载导致了Ti_2CO_2表面上的电荷进行重新分配,并且显著改善了H_2S分子与Ti_2CO_2之间的相互作用,从而提高SACs的催化活性。为了深入理解硫化氢分子的催化处理过程及其分解机理(H_2S→HS~*+H~*→H2+S~*),本研究对硫化氢分子在Ti/Ti_2CO_2和V/Ti_2CO_2表面上的分解反应路径进行了对比分析。结果表明:硫化氢分子在被Ti和V负载的Ti_2CO_2表面上都能够自动解离形成-HS基团和一个质子(HS~*/H~*),而且在V负载的Ti_2CO_2的SACs上,整条路径的速率限制步骤所要跨越的能垒低至0.28e V,该结果表明H_2S分子可在室温下能容易地被单原子催化剂V/Ti_2CO_2解离成H_2分子和S原子,而且S原子能够在该催化剂表面团聚形成稳定的单质硫,从而完成催化循环。此外,使用该SACs催化剂分解H_2S,相比于已经报道过的其它体系的催化剂,无论是在可持续经济角度还是处理能力方面都有较好的应用前景。综上所述,我们发现V负载的Ti_2CO_2催化剂能够高效催化分解硫化氢气体。     

Ga2S3∶Eu2+和SrGa2+xS4+y∶Eu2+系列荧光粉的发光性能研究

采用高温固相法合成了Ga2S3∶Eu2+和SrGa2S4∶Eu2+系列荧光粉. 发现Ga2S3∶Eu2+的发射峰位于570 nm附近, SrGa2S4∶Eu2+的发射峰位于535 nm附近. 同时进一步探讨了SrGa2+xS4+y∶Eu2+体系中, 过量的Ga对发光的影响, 通过漫反射光谱和XRD谱确定过量的Ga是以Ga2S3的形式存在于SrGa2S4相中; 通过荧光光谱发现过量的Ga并不引起SrGa2S4∶Eu2+发射峰的位移, 而是增强其在400～520 nm处激发峰的强度, 从而增强Eu2+在535 nm处的发光强度.     

静电S+X-I+组装途径合成中孔杂原子分子筛

During the last years there has been an increas ing interest in new mesoporous molecular sieves con taining transition metal cations in their framework.Substitution of Si by Ti or V may provide zeolites with dramatic selective catalytic activity. The incor poration of titanium, vanadium and chromium into the silicate MCM-41 framework by electrostatic S+ I- assembly pathway under hydrothermal condi tions at 100～150 ℃ has been reported[1]. Here,we prepared some transition metal-containing meso porous molecular sieves Me-MCM-41 (Me= Ti, V,Cr, Mo, Mn, Zr, W) at ambient temperature through the halogen anion mediated S+ X I + as sembly pathway[2] (S+ -cationic quaternary ammo nium ion surfactants; X -halogen anion C1- or Br-; I+-cationic silicate precursors), by the hy drolysis of silicon source and transition metal source in strongly acidic medium, and in the presence of cetyl trimethyl ammonium bromide (CTMABr) as templating species.     

S2O2-8派生氧化法催化降解水中的甲基橙

 S2O2-8在Ag+的催化作用下可生成 SO-4· 和Ag2+, SO-4· 和Ag2+ 具有极强的氧化能力,其电极电位分别为E0Ag2+/Ag+=1.989 V, E0SO-4·/SO2-4=3.64 V. 本文研究了S2O2-8+Ag+体系中甲基橙的降解情况,并用紫外光谱、总有机碳(TOC)和高效液相色谱/质谱对降解过程进行了表征. 在pH=1的S2O2-8+Ag+体系中,反应8 min时, 5 μmol/L的甲基橙色度去除率达100%. 2 h后,水样中有悬浮物出现,过滤后样品TOC去除率为8.6%; 在同样条件下, Fenton法对甲基橙TOC去除率为10%. 在促使有机物矿化方面, S2O2-8+Ag+法与Fenton法的效果基本相同.     

岩石成因网上n+2相组合平衡p-T线锥的构筑

本文首先讨论了p-T图上围绕无变度点周围n+2相组合反应方程的建立,进而着重提出了利用符号函数矩阵VF或SF确定单变度反应线排布的新算法,其中V和S分别为n+2个单变度反应的△V(体积变化)和△S(熵变化)值的符号函数的对角矩阵,F为反应中各相化学计量系数的符号函数矩阵,算得VF或SF即可确定排布。由这种算法,大大简化相应计算机程序,从而实现了n+2相组合平衡p-T线锥的自动构筑,并使进一步自动构筑完整p-T网成为可能。     

Sr1-x Znx Y2 S4:Er3+,Eu2+荧光粉的合成与发光特性的研究

采用碳酸盐前躯体高温分解法合成了Sr1-xZnxY2S4:Er3+, Sr1-xZnxY2S4:Eu2+和Sr1-xZnxY2S4:Er3+, Eu2+红色荧光粉. XRD图谱表明, Zn2+掺杂量x<0.2 mol 时, 粉末样品为CaFe2O4型正交晶体. Zn2+离子在Sr1-xZnxY2S4:Er3+, Eu2+中的固溶量(x mol)对荧光粉的发射强度影响很大. 随着Zn2+离子掺杂浓度的增加, Sr1-xZnxY2S4:Er3+, Eu2+(SZYSEE)紫外区激发峰(200～413 nm)发生红移, 并与可见光激发带(413～600 nm)形成一个连续的宽带谱, 与紫外和GaN基LED芯片辐射都有良好的匹配性. 当Zn2+掺杂量为0.1 mol时, SZYSEE的发光强度达到最大, 其发光强度比未掺Zn2+的增强10.7倍. Sr0.9Zn0.1Y1.76S4:0.24Er3+, 0.006Eu2+是一种潜在的白光LED用红色荧光粉.     

STRUCTURE OF {Mo4S4（μ—OAc）2[S2P（OC2H5）2]4H}

<正> {Mo4S4(μ-OAc)2(dtp)4H}3,(dtp=S2P(OEt)2),Mr=1371.60,Or-thorhombic, space group Pcab, a = 18. 90 (2) ,b = 21. 678 (4 ) , c = 24. 491 (4 ) A , V = 10031(7)A3,Z=8,Dc=1.818g/cm-3,F(000)=5464,λ(MoKa)=0.71073A,finalR= 0. 069 for 3738 independent reflections. This is a successful example of the formation of [Mo4S4]5+ from[3+1] reaction mode. The results of the structure determination indicate that the configuration of the title compound exhibits a tetranuclear cubane-type core [Mo4S4]5+ with six Mo - Mo distances in the range 2. 685~2. 969A and is very similar to that of the previously characterized compound {Mo4S4(μ-OAc)2(dtp)4}2, [Mo4S4]6+, which was obtained directly by the reaction of MoCl3·3H2O with dtp. Some notable differences, however, can be found when six Mo - Mo bond distances and bonding parameters of the four terminal bidentate ligands (dtp) are compared between these two compounds , That can be attributed to the difference in the oxidation state of these two clusters .     

Ho3+对CaGa2S4:Eu2+发光性能的影响

研究了二价铕离子与三价钬离子共同掺杂的荧光体CaGa2S4:Eu2 (0.5%), Ho3 (1.0%)的荧光、三维热释发光及其长余辉发光特性. 作为对比, 同时研究了CaGa2S4:Eu2 (0.5%)及CaGa2S4:Ho3 (1.0%)的荧光和三维热释发光性质, 发现CaGa2S4:Eu2 (0.5%), Ho3 (1.0%)的发射波长为552 nm的黄绿色余辉长达40 min, CaGa2S4:Eu2 (0.5%)不具有长余辉, 而CaGa2S4:Ho3 (1.0%)具有很弱的余辉. 热释光及其三维图谱的研究表明, 由于Ho3 的引入而产生了一个新的陷阱能级, 从而使CaGa2S4:Eu2 (0.5%), Ho3 (1.0%)具有长余辉的发光特性.     

高选择性快速检测Hg2+的磺酰腙型探针的合成及其在吸附和HeLa细胞中的应用

以苯磺酰肼和4-二苯胺基苯甲醛为原料,通过缩合反应设计和合成了一种新型磺酰腙汞离子(Hg²⁺)探针N’-(4-(二苯氨基)亚苄基)苯磺酰腙(S1).在二甲基亚砜(DMSO)/H₂O(V∶V=7∶3,pH=7)溶液体系中,S1对Hg²⁺展示出快速响应、高选择和高荧光灵敏性.通过¹H NMR和HRMS探究了可能的机理.聚丙烯酰胺(PAM)掺杂S1(PAMS)对Hg²⁺有高的吸附性能,其去除率达到99.99%,并且在紫外灯下通过肉眼很容易区分.通过扫描电子显微镜(SEM)观察了PAMS吸附前后的微观形貌.此外,S1具有优异的生物相容性,可以极好地检测HeLa细胞中的Hg²⁺.     

单个水分子对HO2+H2S反应主通道影响的理论研究

采用CCSD(T)/aug-cc-pVTZ//B3LYP/6-311+G(2df,2p)方法对HO2+H2S反应及单分子水参与其主通道的微观机理和速率常数进行了研究.结果表明,HO2+H2S反应主通道为生成产物为H2O2+HS的通道,其表观活化能为14.94 kJ/mol.考虑单分子水对主产物通道的影响发现,所得的势能面比无水参与的反应复杂得多,经历了H2O…HO2+H2S(RW1),HO2…H2O+H2S(RW2)和H2O…H2S+HO2(RW3)3个通道,RW1~RW6共6个路径.其中通道RW1是水分子参与HO2+H2S反应主通道的优势通道.在216.7~298.2K温度范围内通道RW1的有效速率常数呈现出正温度系数效应,在298 K时,k’RW 1/ktotal达到54.2%,表明在实际大气环境中水分子对HO2+H2S反应的主通道具有明显影响.     

Synthesis and magnetic and transport properties of Sr6V9S22O2: "AM2S5" phases revisited

The compound Sr6V9S22O2 was prepared from SrS, sulfur, vanadium metal, and V2O5 at 950 degrees C in an evacuated quartz tube. The compound is rhombohedral, R3, with a = 8.7538(6) A, c = 34.934(3) A, and Z = 3, and shows strong preferred orientation in its XRD profiles (00l) due to the layered nature of the structure. The compound contains charged CdI2 type VS2 layers of formula [V7S14]4- separated by [Sr6(VOS3)2(S2)]4+ layers. The latter has VOS3(3-) tetrahedra and S2(2-) disulfide units linked by Sr2+ ions. Magnetic susceptibility and four-probe resistivity studies show essentially temperature-independent paramagnetism above 80 K and small gap semiconductor behavior, respectively. The compound has a positive Hall coefficient at room temperature. The relationship among Sr6V9S22O2, "SrV2S5" (J. Solid State Chem. 1996, 126, 189), and other AM2S5 phases is discussed.     

NC2S+离子的结构和稳定性的理论研究

在密度泛函和从头算理论水平下计算了单重态的NC2S+离子的结构、能量、光谱以及稳定性. 在B3LYP/6-311G(d)水平下, 得到8个异构体, 它们由15个过渡态相连接. 在CCSD(T)/6-311+G(2df)//QCISD/6-311G(d)+ZPVE水平下, 得到能量最低的异构体是直线型的具有1Σ电子态的NCCS+(1)(0.0 kJ/mol), 其次是直线型的异构体CNCS+(2)(54.8 kJ/mol). 两个低能量的异构体1和2及另外一个高能量的直线型异构体CCNS+(3)(323.8 kJ/mol)都具有相当大的动力学稳定性, 这三个异构体在具备一定条件的实验室和星际条件下是可以进行观测的. 分析了这3个异构体的成键性质.     

EPR parameters and local geometry for Cr3+ and V2+ ions in HfS2 crystals

From the high-order perturbation formulas of EPR parameters (zero-field splitting D, g factors gparallel, gperpendicular and hyperfine structure constants Aparallel, Aperpendicular) based on the two spin-orbit coupling parameter model for 3d3 ions in trigonal symmetry, the EPR parameters of Cr3+ and V2+ ions in HfS2 crystals are calculated. From the calculations, it is found that the local trigonal distortion angle theta of impurity center in HfS2:Cr3+ is smaller than that in HfS2:V2+. The dominant cause of the small zero-field splitting |D| and g-anisotropy |Deltag|=|gparallel-gperpendicular| in HfS2:Cr3+ (compound to HfS2:V2+) is due to the small local trigonal distortion angle theta rather than to the small impurity-ligand distance R in HfS2:Cr3+.     

New chemistry of the triply bonded divanadium (V2 4+) unit and reduction to an unprecedented V2 3+ core

We report here the synthesis and characterization of seven new divanadium compounds with the paddlewheel geometry bridged by nitrogen-donating ligands. Five of these contain the diamagnetic V(2)(4+) core with short V-V distances of less than 2.0 A, consistent with a formal triple bond. The V-V distances vary with the basicity of the bridging ligands; more basic ligands such as those of the guanidinate type have the shorter metal-metal separations, and those with the less basic formamidinate groups have longer separations. One compound, V(2)(DPhF)(4) (DPhF = the anion of N,N'-diphenylformamidine), has been reduced by one electron, and two structures, [K(THF)(3)]V(2)(DPhF)(4) and [K(18-crown-6)(THF)(2)]V(2)(DPhF)(4), have been obtained. These have an unprecedented V(2)(3+) core where the formal oxidation state of each vanadium atom is +1.5. The decrease in V-V bond distance and the multiline EPR spectrum in the reduced species provide evidence that these two molecules contain a bond of order 3.5.     

Cooperative radiative and nonradiative effects in K2NaScF6 codoped with V3+ and Er3+

K2NaScF6 crystals codoped with V3+ and Er3+ exhibit some novel cooperative near-IR to visible upconversion processes at cryogenic temperatures. V3+ mainly acts as a broadband sensitizer. The V3+ 3T1g --> 3T2g excitation between 13,500 and 15,500 cm(-1), after fast relaxation to V3+ 1T2g, can be transferred to Er3+ 4I(11/2), and then upconversion takes place. Four upconversion mechanisms are identified and characterized. For narrow-band laser excitation the overall efficiency of the upconversion processes is low. However, at 12 K for broadband excitation, such as in a lamp, between 12,000 and 14,500 cm(-1) the number of emitted visible photons is roughly doubled by codoping V3+ in addition to Er3+.     

Studies of electron paramagnetic resonance parameters and defect structures for Ti2+ and V3+ ions in CdS crystals

By applying the high-order perturbation formulas based on the cluster approach for the EPR parameters of 3d2 ions in trigonal symmetry, the zero-field splitting D, g factors gparallel, gperpendicular, and hyperfine structure constants Aparallel, Aperpendicular for Ti2+ and V3+ ions in CdS crystals are studied. From the studies, the defect structures of these paramagnetic impurity centers are obtained and the EPR parameters are also explained reasonably.     

纳米BaAl2S4:Eu2+发光材料的制备及性能

采用溶胶-凝胶法合成了纳米荧光粉BaAl2S4:Eu2+, 并对其性能进行了研究.     

热分解法制备Y_2O_2S∶Eu~(3+)纳米粒子(英文)

采用热分解法和硫熔法分别合成了纳米Y2O2S∶Eu3+和体相Y2O2S∶Eu3+。其中硫氧化钇纳米粒子的制备是以水热法合成的Y(OH)3为前驱体,随后在激活剂和硫的共同作用下焙烧得到的。结果表明,所得Y2O2S∶Eu3+为单一纯相纳米粒子,粒径分布集中,大小约80nm,而前驱体Y(OH)3为纳米棒状,形貌上的这一巨大变化是由激活剂和硫粉在高温煅烧过程所形成的熔融物的腐蚀作用造成的。荧光光谱分析表明,Eu3+能有效地掺入硫氧化钇基质中,并具有良好的发光性能。此外,还探讨了纳米粒子的形成机理。     

Theoretical investigation on the electronic and geometric structure of GaN2+ and GaN4+

The electronic and geometric structures of gallium dinitride cation, GaN2+ and gallium tetranitride cation, GaN4+ were systematically studied by employing density functional theory (DFT-B3LYP) and perturbation theory (MP2, MP4) in conjunction with large basis sets, (aug-)cc-pVxZ, x = T, Q. A total of 7 structures for GaN2+ and 24 for GaN4+ were identified, corresponding to minima, transition states, and saddle points. We report geometries and dissociation energies for all the above structures as well as potential energy profiles, potential energy surfaces, and bonding mechanisms for some low-lying electronic states. The calculated dissociation energy (De) of the ground state of GaN2+, X1Sigma+, is 5.6 kcal/mol with respect to Ga+(1S) + N2(X1Sigmag+) and that of the excited state, ?3Pi, is 24.8 kcal/mol with respect to Ga+(3P) + N2(X1Sigmag+). The ground state and the first excited minimum of GaN4+ are of 1A1(C2v) and 3B1(C2v) symmetry with corresponding De of 11.0 and 43.7 kcal/mol with respect to Ga+(1S) + 2N2(X1Sigmag+) for X1A1 and Ga+(3P) + 2N2(X1Sigmag+) for 3B1.     

Effects of Ca2+ and V5+ on glucose-6-phosphatase activity in rat liver microsomes: the Ca2+ effect is reversed by regucalcin

The effect of regucalcin, a calcium-binding protein isolated from rat liver cytosol, on glucose-6-phosphatase in the microsomes of rat liver was investigated. Addition of Ca2+ up to 2.5 microM to the enzyme reaction mixture caused a significant increase of glucose-6-phosphatase activity in hepatic microsomes, while Ni2+, Zn2+, Cd2+, Cu2+, Mn2+ and Co2+ (20 microM) did not have an appreciable effect. Vanadate (V5+) markedly inhibited the enzyme activity; a significant inhibitory effect was seen at 10 microM V5+. The Ca2+-induced increase of glucose-6-phosphatase activity was reversed by the presence of regucalcin; the effect was complete at 1.0 microM of the protein. Regucalcium had no effect on the basal activity of the enzyme. Meanwhile, the inhibitory effect of V5+ (10-100 microM) on glucose-6-phosphatase was not appreciably blocked by the presence of regucalcin (up to 2.0 microM). The present data suggest that hepatic microsomal glucose-6-phosphatase is uniquely regulated by Ca2+ and V5+, of various metals, and that the Ca2+ effect is reversed by regucalcin. The present study supports the view that regucalcin plays an important role as a regulatory protein in liver cell function related to Ca2+.