首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 234 毫秒
1.
赵大洲 《合成化学》2018,26(10):776-778
利用介孔SiO2微球(MSM)作为基底,对其表面进行氨基修饰,合成了氨基修饰介孔SiO2微球(MSM/NH2),其结构和性能经TEM, XRD和元素分析表征。结果表明:MSM/NH2 1.0[3-氨丙基三乙氧基硅烷(APTES)用量为1.0 mL]对Hg2+、 Ni2+和Mn2+的5次循环吸附效率的平均值均超过92.0%。  相似文献   

2.
近年来,低维无铅金属卤化物由于其独特的光学性质、低毒性和优异的环境稳定性等优点受到了广泛关注。采用水热法成功制备Cs2ZnCl4∶Ce3+、Cs2ZnCl4∶Mn2+以及Cs2ZnCl4∶Ce3+,Mn2+等微米晶,并利用X射线衍射仪、荧光光谱仪等表征手段对其物相和发光特性进行了系统性研究。研究结果表明,Cs2ZnCl4微米晶为正交相零维结构,其发射光谱依赖于掺杂离子的激发波长,例如,Ce3+离子掺杂的Cs2ZnCl4微米晶在254nm的激发条件下,其发射光谱峰位位于350nm,对应于Ce3+离子4f-5d的跃迁;Mn2+离子掺杂的Cs2ZnCl4微米晶在361nm的激发条件...  相似文献   

3.
以商用活性炭(AC)为原料,分别采用磷酸和氢氧化钠改性的方法制备了两种不同的改性活性炭电极材料.采用扫描电子显微镜(SEM)、透射电子显微镜(TEM)、 Brunauer-Emmett-Teller(BET)测试、傅里叶变换红外光谱(FTIR)和X射线光电子能谱(XPS)等手段以及电化学分析方法,对改性前后活性炭材料的表面性质和电化学性能进行了探究.结果表明, H3PO4改性使活性炭的孔隙分布更加密集, NaOH改性使活性炭表面的孔隙结构更加清晰均匀; H3PO4和NaOH改性均使活性炭的比表面积增加.循环伏安测试结果表明,改性前后活性炭电极在低扫描速率下均具备良好的双电层特性,并且两种改性处理均能提高活性炭电极的比电容;当扫描速率为5 mV/s时,未改性、 H3PO4以及NaOH改性活性炭电极的比电容分别为36.51, 77.25和85.19 F/g.电吸附实验结果证明,两种改性活性炭电极对Co2+, Mn2+和Ni2+均有较好的去...  相似文献   

4.
采用水热法制备了均匀、单分散的BaF2∶Tb3+纳米粒子,并采用离子交换法制备了水杨酸钠敏化的BaF2∶Tb3+纳米粒子(SS-BaF2∶Tb3+)。 系统地研究了样品的结构、形貌和光致发光性质。 结果表明,监测Tb3+离子在547 nm的5D47F5跃迁,SS-BaF2∶Tb3+纳米粒子获得了从200 nm到385 nm波长范围宽的激发带;激发SS的π-π*电子跃迁吸收,由于SS到Tb3+的能量传递(“天线效应”),SS-BaF2∶Tb3+纳米粒子产生了增强的Tb3+离子绿光发射;敏化纳米粒子中Tb3+离子光致发光寿命比未敏化纳米粒子中Tb3+离子寿命长。  相似文献   

5.
采用水热法合成了不同比例Al3+离子掺杂的δ-MnO2纳米粉体.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)、 X射线光电子能谱(XPS)、循环伏安(CV)曲线、电化学阻抗谱(EIS)和恒电流充放电(GCD)曲线等手段对材料的结构和电化学性能进行了表征.结果表明, Al3+离子进入δ-MnO2的晶格替代部分Mn3+和Mn4+离子,使得δ-MnO2电极的性能明显提升.当反应物中Al3+/Mn2+摩尔比为0.45时,所得样品(A0.45M)的性能最好;其在1 A/g电流密度下的比电容为207.61 F/g,是纯相δ-MnO2(A0M)的2.4倍;其在10 A/g电流密度下循环10000次后的比电容为100.81 F/g,容量保持率为81.33%.  相似文献   

6.
研究了Keggin结构钼磷杂多化合物Na5[PM(H2O)Mo11O39]·nH2O(M=Mn2+,Co2+,Ni2+,Cu2+,Zn2+在溶液中的氧化还原性质,发现环境的改变可对杂多阴离子的极谱半波电位产生影响,其影响程度的大小决定于过渡金属离子本身的性质。取代后的钼磷杂多阴离子的半波电位顺序为Ni2+>Co2+>Zn2+>Cu2+>Mn2+,pH值的变化影响氧化还原性质,并阐述了变价金属Cu2+对杂多阴离子氧化还原性质的影响.  相似文献   

7.
研究了Mn/Ce摩尔比、反应温度、氧气和水对MnOx-CeO2催化剂催化氯苯氧化性能(活性、选择性和稳定性)的影响,并分析了其理化性能、作用过程和反应机理.结果表明,在含H2Ogas和O2(体积分数均为5%)条件下,Mn2Ce1Ox在100,200和300℃下分别取得了80.6%,86.8%和97.5%的氯苯转化率;反应温度和氧气含量的增加及水的存在均有利于提高催化活性和反应稳定性;MnOx和CeO2复合提高了比表面积(128.61 m2/g)、降低了孔径(6.17 nm)且增强了表面酸性(中酸和强酸位点)和氧化还原能力,价态电子交互循环过程(Ce4+/Ce3+←→—Mn4+/Mn3+/Mn2+)和氧循环作用(吸附氧←→—晶格氧)是催化反应...  相似文献   

8.
采用滴涂法在铂基底制备了电活性聚苯胺-磷酸锡(PANI-SnP)复合膜电极,考察了该电极在Ni2+、Cd2+溶液的电控离子交换性能. 用傅立叶变换红外光谱和扫描电镜分析观察复合膜的组成及表面形貌;在0.1 mol·L-1 Ni(NO3)2、Cd(NO3)2溶液,通过循环伏安法比较了PANI膜、SnP膜及PANI-SnP复合膜电极的电化学性能,并结合电化学石英晶体微天平技术重点考察了PANI-SnP复合膜的离子交换机制;同时,通过循环伏安法调控复合膜电极的氧化还原电位,结合X射线能谱和X射线光电子能谱分别测定了其氧化和还原状态的元素组成. 结果表明,PANI-SnP复合膜电极在Ni2+、Cd2+溶液均有良好的氧化还原电活性和可逆离子交换性能,其Cd2+离子选择性优于Ni2+离子,通过电控离子交换可使Cd2+离子从镍镉废水高效分离.  相似文献   

9.
建立了一种以牛血清白蛋白功能化的金纳米棒(BSA-Cys-GNRs)为荧光探针检测Hg2+的新方法。以半胱氨酸作为连接臂成功将牛血清白蛋白修饰在金纳米棒表面,通过紫外可见吸收光谱、荧光光谱、红外光谱和荧光倒置显微镜等多种分析方法对材料进行表征。研究发现,在295nm波长光激发下,BSA-Cys-GNRs探针在338nm显示强荧光,而Hg2+能够有效地猝灭BSA-Cys-GNRs的荧光。对一系列影响猝灭效果的因素进行考察,得出pH 4.0、孵育时间5.0min为最佳检测条件。Mn2+、K+、Ni2+、Na+、Cr3+、Cd2+、Mg2+、Cu2+、Ca2+、Al3+和Zn2+对BSA-Cys-GNRs的荧光信号没有明显的影响。当Hg2+的浓度为0.04444~8.888μmol·L-1时,荧光猝灭效率与Hg2+的浓度之间存在良好的线性关系,检测限为8.08nmol·L-1。将该方法用于环境水样中Hg2+的检测,回收率为98.9%~105.0%。  相似文献   

10.
采用尿素沉淀法制备一系列Bi3+/La3+共掺Lu2O3和Bi3+/Lu3+共掺La2O3微米晶。在掺杂Bi3+离子的Lu2O3微米晶中,C2位点的Bi3+离子可以将吸收的能量转移给S6位点的Bi3+离子。同时,在Lu2O3:1%Bi3+,0~5%(摩尔分数,下同)La3+微米晶中,372和337 nm(C2和S6位点的Bi3+离子)紫外光的激发下,Bi3+离子的发射峰强度随着La3+离子掺杂浓度的增加而增加,掺杂5%La3+时与不掺杂La  相似文献   

11.
Samples of Li(x)Ni0.5Mn0.5O2 and Li(x)Ni(1/3)Mn(1/3)Co(1/3)O2 were prepared as active materials in electrochemical half-cells and were cycled electrochemically to obtain different values of Li concentration, x. Absorption edges of Ni, Mn, Co, and O in these materials of differing x were measured by electron energy loss spectrometry (EELS) in a transmission electron microscope to determine the changes in local electronic structure caused by delithiation. The work was supported by electronic structure calculations with the VASP pseudopotential package, the full-potential linear augmented plane wave code WIEN2K, and atomic multiplet calculations that took account of the electronic effects from local octahedral symmetry. A valence change from Ni2+ to Ni4+ with delithiation would have caused a 3 eV shift in energy of the intense white line at the Ni L3 edge, but the measured shift was less than 1.2 eV. The intensities of the "white lines" at the Ni L-edges did not change enough to account for a substantial change of Ni valence. No changes were detectable at the Mn and Co L-edges after delithiation either. Both EELS and the computational efforts showed that most of the charge compensation for Li+ takes place at hybridized O 2p states, not at Ni atoms.  相似文献   

12.
通过共沉淀法制备了M(OH)2(M=Mn, Ni)前驱体, 并与LiOH混合, 合成了锂离子电池富锂正极材料Li[NixLi1/3-2x/3Mn2/3-x/3]O2, 采用XRD、SEM和充放电实验对其进行表征. 研究结果表明, Li, Ni, Mn原子在M层中呈有序分布, 形成超结构; 富锂正极材料由亚微米的一次粒子团聚组成1~3 μm颗粒; 在2.0~4.8 V电位范围内, 充放电电流密度为10 mA/g时, 富锂正极材料表现出很高的可逆比容量, 达到200~240 mA·h/g, 同时具有良好的循环可逆性能.  相似文献   

13.
A non-cadmium and water-soluble Mn-doped ZnO(x)S(1-x) QDs was synthesized with denatured bovine serum albumin (dBSA) as stabilizer under nitrogen atmosphere, and the as-prepared products were characterized by X-ray powder diffraction (XRD), UV-vis absorption spectroscopy, fluorescence (FL) emission spectroscopy, high resolution transmission electronmicroscopy (HRTEM) and Raman spectrum. XRD patterns indicate that the Mn-doped ZnO(x)S(1-x) QDs have a zinc-blende structure, and that manganese emerges in the form of divalent manganese (Mn(2+)) and trivalent manganese (Mn(3+)) (the intermediate of the reaction). The size of Mn-doped ZnO(x)S(1-x) QDs is about 3.2±0.7 nm according to HRTEM imaging. The FL spectra reveal that the Mn-doped ZnO(x)S(1-x) QDs have two distinct emission bands: the defect-related emission and the Mn(2+)-related emission, which exhibit a competing process. A good FL signal of the transition of Mn(2+) ((4)T(1)-(6)A(1)) is observed when the doping amounts are 1.0% and 20% respectively, and the as-prepared solutions are stable for more than 6 months at 4°C. This method has the advantages of good stability and environment-friendly stabilizer, for involving no heavy metal ions or toxic reagents.  相似文献   

14.
The synthesis, crystal structure, and physical characterization of the coordination compounds [Ni(en)2]4[Fe(CN)5NO]2[Fe(CN)6]x5H2O (1), [Ni(en)2][Fe(CN)5NO]x3H2O (2), [Mn(3-MeOsalen)(H2O)]2[Fe(CN)5NO] (3), and [Mn(5-Brsalen)]2[Fe(CN)5NO] (4) are presented. 1 crystallizes in the monoclinic space group P2(1)/n (a = 7.407(4) A, b = 28.963(6) A, c = 14.744(5) A, alpha = 90 degrees, beta = 103.26(4) degrees, gamma = 90 degrees, Z = 2). Its structure consists of branched linear chains formed by cis-[Ni(en)2]2+ cations and ferrocyanide and nitroprusside anions. The presence of two kinds of iron(II) sites has been demonstrated by M?ssbauer spectroscopy. 2 crystallizes in the monoclinic space group P2(1)/c (a = 11.076(3) A, b = 10.983(2) A, c = 17.018(5) A, alpha = 90 degrees, beta = 107.25(2) degrees, gamma = 90 degrees, Z = 4). Its structure consists of zigzag chains formed by an alternated array of cis-[Ni(en)2]2+ cations and nitroprusside anions. 3 crystallizes in the triclinic space group P1 (a = 8.896(5) A, b = 10.430(5) A, c = 12.699(5) A, alpha = 71.110(5) degrees, beta = 79.990(5) degrees, gamma = 89.470(5) degrees, Z = 1). Its structure comprises neutral trinuclear bimetallic complexes in which a central [Fe(CN)5NO]2- anion is linked to two [Mn(3-MeOsalen)]+ cations. 4 crystallizes in the tetragonal space group P4/ncc (a = 13.630(5) A, c = 21.420(8) A, Z = 4). Its structure shows an extended 2D neutral network formed by cyclic octameric [-Mn-NC-Fe-CN-]4 units. The magnetic properties of these compounds indicate the presence of quasi-isolated paramagnetic Ni2+ and Mn3+. Irradiated samples of the four compounds have been studied by differential scanning calorimetry to detect the existence of the long-lived metastable states of nitroprusside.  相似文献   

15.
The new, monometal substituted silicotungstates [Mn(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (1), [Co(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (2) and [Ni(H(2)O)(2)(gamma-SiW(10)O(35))(2)](10-) (3) have been synthesized and isolated as the potassium salts K(10)[Mn(H(2)O)(2)(gamma-SiW(10)O(35))(2)] x 8.25 H(2)O (K-1), K(10)[Co(H(2)O0(2)(gamma-SiW(10)O(35))(2)] x 8.25 H(2)O (K-2) and K(10)[Ni(H(2)O)(2)(gamma-SiW(10)O(35))(2)] x 13.5 H(2)O (K-3), which have been characterized by IR spectroscopy, single crystal X-ray diffraction, elemental analysis and cyclic voltammetry. Polyanions 1-3 are composed of two (gamma-SiW(10)O(36)) units fused on one side via two W-O-W' bridges and on the other side by an octahedrally coordinated trans-MO(4)(OH(2))(2) transition metal fragment, resulting in a structure with C(2v) point group symmetry. Anions 1-3 were synthesized by reaction of the dilacunary precursor [gamma-SiW(10)O(36)](8-) with Mn(2+), Co(2+) and Ni(2+) ions, respectively, in 1 M KCl solution at pH 4.5. The electrochemical properties of 1-3 were studied by cyclic voltammetry and controlled potential coulometry in a pH 5 buffer medium. The waves associated with the W-centers are compared with each other and with those of the parent lacunary precursor [gamma-SiW(10)O(36)](8-) in the same medium. They appear to be dominated by the acid-base properties of the intermediate reduced species. A facile merging of the waves for 3 is observed while those for 1 and 2 remain split. Controlled potential coulometry of the single wave of 3 or the combined waves of 1 and 2 is accompanied by catalysis of the hydrogen evolution reaction. No redox activity was detected for the Ni(2+) center in 3, whereas the Co(2+) center in 2 shows a one-electron redox process. The two-electron, chemically reversible process of the Mn(2+) center in 1 is accompanied by a film deposition on the electrode surface.  相似文献   

16.
Novel mono-and binuclear metal complexes of Ni(II) based on 1-aryl-3-aryl(alkyl)-5-(benzothiazole-2-yl)formazanes were synthesized and their structures were studied by the electronic and IR spectroscopy, mass spectrometry and megnetochemical methods.  相似文献   

17.
Mn(III)-Ni(II)-Mn(III) linear-type trinuclear complexes bridged by oximate groups were selectively synthesized by the assembly reaction of [Mn2(5-Rsaltmen)2(H2O)2](ClO4)2 (5-Rsaltmen2-=N,N'-(1,1,2,2-tetramethylethylene) bis(5-R-salicylideneiminate); R=Cl, Br) with [Ni(pao)2(phen)] (pao-=pyridine-2-aldoximate; phen=1,10-phenanthroline) in methanol/water: [Mn2(5-Rsaltmen)2Ni(pao)2(phen)](ClO4)2 (R=Cl, 1; R=Br, 2). Structural analysis revealed that the [Mn(III)-ON-Ni(II)-NO-Mn(III)] skeleton of these trimers is in every respect similar to the repeating unit found in the previously reported series of 1D materials [Mn2(saltmen)2Ni(pao)2(L1)2](A)(2) (L(1)=pyridine, 4-picoline, 4-tert-butylpyridine, N-methylimidazole; A=ClO4-, BF4-, PF6-, ReO4-). Recently, these 1D compounds have attracted a great deal of attention for their magnetic properties, since they exhibit slow relaxation of the magnetization (also called single-chain magnet (SCM) behavior). This unique magnetic behavior was explained in the framework of Glauber's theory, generalized for chains of ferromagnetically coupled anisotropic spins. Thus, in these 1D compounds, the [Mn(III)-ON-Ni(II)-NO-Mn(III)] unit was considered as an S(T)=3 anisotropic spin. Direct-current magnetic measurements on 1 and 2 confirm their S(T)=3 ground state and strong uniaxial anisotropy (D/k(B) approximately -2.4 K), in excellent agreement with the magnetic characteristic deduced in the study on the SCM series. The ac magnetic susceptibility of these trimers is strongly frequency-dependent and characteristic of single-molecule magnet (SMM) behavior. The relaxation time tau shows a thermally activated (Arrhenius) behavior with tau0 approximately 1x10(-7) s and Delta(eff)/k(B) approximately 18 K. The effective energy barrier for reversal of the magnetization Delta(eff) is consistent with the theoretical value (21 K) estimated from |D| S2T. The present results reinforce consistently the interpretation of the SCM behavior observed in the [Mn2(saltmen)2Ni(pao)2(L1)2](A)2 series and opens new perspectives to design single-chain magnets.  相似文献   

18.
Two heterotrinuclear complexes, [Mn(II)(Ni(II)L)2].2CH3OH (where H3L = 1,1,1-tris(N-salicylideneaminomethyl)ethane) and [Fe(III)(Ni(II)L)2]NO3.C2H5OH, consisting of three face-sharing octahedra have been prepared; although these complexes have closely related structures and have the same 1-5/2-1 spin system, they show completely different magnetic interactions between the adjacent metal ions: ferromagnetic (Ni(II)-Mn(II)) and antiferromagnetic (Ni(II)-Fe(III)).  相似文献   

19.
A series of single-chain magnets, [Mn2(saltmen)2Ni(pao)2(L)2](A)2 (saltmen(2-)=N,N'-(1,1,2,2-tetramethylethylene) bis(salicylideneiminate), pao-=pyridine-2-aldoximate; A-=ClO4- with L=4-picoline; 2, 4-tert-butylpyridine; 3, N-methylimidazole; 4, and L=pyridine with A-=BF4-; 5, PF6-; 6, ReO4-; 7), was prepared by reactions between MnIII dimer units, i.e., [Mn2(saltmen)2(H2O)2](A)2 (A-=ClO4-, BF4-, PF6-) or Mn2(saltmen)2(ReO4)2, and NiII monomeric units, i.e., Ni(pao)2(L)2, in methanol/water media. The crystal structures of 4, 6, and 7 were established by single-crystal X-ray crystallography. These three compounds are isostructural with [Mn2(saltmen)2Ni(pao)2(py)2](ClO4)2 (1) (Clérac, R.; Miyasaka, H.; Yamashita, M.; Coulon, C. J. Am. Chem. Soc. 2002, 124, 12837) and crystallize in monoclinic space group C2/c. The linear arrangement of MnIII dimer units and NiII building blocks leads to an alternating chain having a repeating unit, [-(O)2-Mn-ON-Ni-NO-Mn-]. The chains are well separated with the nearest interchain intermetallic distance of 10.36 A for 4, 10.51 A for 6, and 10.30 A for 7, and there is no significant pi-pi interchain interaction between ligands. The void space between the chains is occupied by counteranions, which control the three-dimensional organization of the chains. The X-ray diffraction analysis (XRD) on a powder sample was also performed for all compounds. The XRD patterns for 1, 2, and 4-7 are very similar, emphasizing the isostructural nature of these materials although they have individually slight different interchain distances. Inversely, the XRD pattern for 3 reveals a completely different shape being indicative of the peculiar crystal packing compared to the others. Nevertheless, the one-dimensional nature of the structure is also kept in 3 as indicated by magnetic measurements. The whole family of compounds exhibits quasi-identical magnetic behavior compared to that described for 1. Above 30 K, the heterometallic chain can be described as an assembly of antiferromagnetically coupled Mn...Ni....Mn trimers (via oximate bridge, -24.2 K相似文献   

20.
Ten compounds belonging to the series of oxygen-deficient perovskite oxides Ca(2)Fe(2-x)Mn(x)O(5) and CaSrFe(2-x)Mn(x)O(5+y), where x = 1/2, 2/3, and 1 and y ≈ 0-0.5, were synthesized and investigated with respect to the ordering of oxygen vacancies on both local and long-range length scales and the effect on crystal structure and magnetic properties. For the set with y ≈ 0 the oxygen vacancies always order in the long-range sense to form the brownmillerite structure containing alternating layers of octahedrally and tetrahedrally coordinated cations. However, there is a change in symmetry from Pnma to Icmm upon substitution of Sr for one Ca for all x, indicating local T(d) chain (vacancy) disorder. In the special case of CaSrFeMnO(5) the neutron diffraction peaks broaden, indicating only short-range structural order on a length scale of ~160 ?. This reveals a systematic progression from Ca(2)FeMnO(5) (Pnma, well-ordered tetrahedral chains) to CaSrFeMnO(5) (Icmm, disordered tetrahedral chains, overall short-range order) to Sr(2)FeMnO(5) (Pm3m, destruction of tetrahedral chains in a long-range sense). Systematic changes occur in the magnetic properties as well. While long-range antiferromagnetic order is preserved, the magnetic transition temperature, T(c), decreases for the same x when Sr substitutes for one Ca. A review of the changes in T(c) for the series Ca(2)Fe(2-x)M(x)O(5), taking into account the tetrahedral/octahedral site preferences for the various M(3+) ions, leads to a partial understanding of the origin of magnetic order in these materials in terms of a layered antiferromagnetic model. While in all cases the preferred magnetic moment direction is (010) at low temperatures, there is a cross over for x = 0.5 to (100) with increasing temperature for both the Ca(2)Fe(2-x)Mn(x)O(5) and the CaSrFe(2-x)Mn(x)O(5) series. For the y > 0 phases, while a brownmillerite ordering of oxygen vacancies is preserved for the Ca(2) phases, a disordered Pm3m cubic perovskite structure is always found when Sr is substituted for one Ca. Long-range magnetic order is also lost, giving way to spin glass or cluster-glass-like behavior below ~50 K. For the x = 0.5 phase, neutron pair distribution function (NPDF) studies show a local structure related to brownmillerite ordering of oxygen vacancies. Neutron diffraction data at 3.8 K show a broad magnetic feature, incommensurate with any multiple of the chemical lattice, and with a correlation length (magnetic domain) of 6.7(4) ?.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号