石墨烯助剂与Ni(Ⅱ)活性位点协同增强TiO2制氢性能

采用水热法和低温浸渍法制备了电子助剂还原石墨烯(rGO)和界面活性位点Ni(Ⅱ)共修饰的高效TiO₂光催化剂(简称Ni(Ⅱ)/TiO₂-rGO)。制氢性能测试结果表明：相比于TiO₂和单独还原石墨烯复合的TiO₂,经还原石墨烯与Ni(Ⅱ)协同修饰后的TiO₂表现出更高的光催化制氢性能。其中,Ni(Ⅱ)/TiO₂-rGO(0.1 mol·L^-1)具有最高制氢性能,制氢速率达到77.0 μmol·h^-1,分别是TiO₂(16.4 μmol·h^-1)和TiO₂-rGO(28.0 μmol·h^-1)的4.70倍和2.75倍。还原石墨烯助剂与Ni(Ⅱ)活性位点协同增强制氢性能的原理是：还原石墨烯作为电子助剂可以快速捕获和传输电子,Ni(Ⅱ)作为界面活性位点可以从溶液中捕获H⁺,提高界面反应速率,2种助剂协同作用加快了TiO₂上的光生电子-空穴对的有效分离。     

S掺杂形式对TiO2基光催化剂结构和性能的影响

采用改进的Sol-gel法制备了S-TiO₂和TiO₂,用1 mol·L^-1的H₂SO₄对TiO₂进行表面修饰制成的SO₄^2-/TiO₂。采用XRD、IR、UV-Vis、SEM和EDS等技术对催化剂的结构进行了表征,以L酸(1-萘酚-5-磺酸)为目标物,考察了所制备的催化剂的性能．结果表明：S-TiO₂的禁带宽度明显降低,并且对400~650 nm区域的可见光都有一定的吸收,其可见光活性和紫外光活性均高于SO₄^2-/TiO₂和纯TiO₂。     

基于层状双氢氧化物前驱体的CO2甲烷化NiAlNd催化剂

采用乙二醇溶剂热法合成了一系列基于层状双氢氧化物前驱体(LDHs)的NiAlNd催化剂。Nd的引入大大提高了CO₂甲烷化的低温催化活性。在 T=210 ℃,WHSV(weight hourly space velocity)=24 000 mL·g^-1·h^-1,p=100 kPa的条件下,NiAlNd-0.4催化剂上CO₂转化率达到83.9%。Nd³⁺取代部分Al³⁺阻碍了前驱体中LDHs结构的形成,同时也减小了焙烧后催化剂的粒径。Nd的加入削弱了NiO与Al₂O₃之间的相互作用,促进了NiO的还原,提高了Ni的本征活性。此外,Nd的添加提高了催化剂表面碱性位的数目,从而增强了对CO₂的吸附。随着Nd掺杂量的增加,还原后的催化剂中金属Ni的表面积呈火山形变化。Ni活性位的数目和本征活性同时影响NiAlNd催化剂的催化活性。     

MO(M=Cu和Ni)/TiO2/γ-Al2O3催化剂在CO+O2反应中的活性

采用X射线衍射(XRD)，程序升温还原(TPR)等表征手段考察了TiO₂改性对CuO(或NiO)在γ-Al₂O₃表面上分散以及还原性能的影响，同时检测了这些改性的催化剂在CO+O₂反应中的活性。结果表明:TiO₂的改性使得CuO和NiO在γ-Al₂O₃载体上的分散复杂化，产生了多种状态的氧化铜(氧化镍)物种。当负载量低于其在γ-Al₂O₃上的分散容量(0.56 mmol Ti⁴⁺/100 m² γ-Al₂O₃)时，TiO₂的加入主要是抑制了CuO和NiO在γ-Al₂O₃载体上的分散;而当负载量远大于其分散容量时，出现了CuO和NiO在晶相TiO₂(锐钛矿)上的分散。无论其负载量如何，TiO₂的加入促进了CuO的还原。因此，在250 ℃的CO+O₂反应中，改性的催化剂中具有更多的活性位，因而显示出更高的活性;相反，TiO₂的改性则抑制了NiO的还原。因此，在350 ℃的CO+O₂反应中，可还原的氧化镍的量明显少于未经改性的催化剂，导致改性催化剂的活性降低。     

纳米TiO2低温水解法的晶型控制合成及其表面织构的研究

分别以TiCl₄，Ti(NO₃)₄和Ti(SO₄)₂为前驱体，在低温和强酸性条件下，通过水解反应可控地合成了具有不同晶相组成，且比表面积较高的纳米TiO₂，并用XRD，TEM和N₂^-吸附脱附技术对其晶相、粒径大小、形貌及比表面积进行了表征。结果表明，钛离子在有Cl^-、NO₃^-存在的酸性溶液中水解，水解温度≤80 ℃，可以生成结晶良好的具有细小晶粒尺寸和较高比表面积的金红石型纳米TiO₂粉体，水解温度>80 ℃，反而有锐钛矿型TiO₂生成，而在有SO₄^2-存在的酸性溶液中，TiO₂样品的晶相组成不随水解温度的变化而改变，均为锐钛矿型，其比表面积可达300 m²·g^-1。     

层状Co3O4的制备及其电化学电容行为

以P123为模板水热合成制备了Co₂(OH)₂CO₃前驱体，200 ℃热处理后得到了具有层状结构的Co₃O₄。循环伏安、恒流放电等电化学测试表明，200 ℃所得Co₃O₄电极在6 mol·L^-1 KOH溶液中和-0.1～0.5 V(vs Ag/AgCl)电位范围内，具有较好的循环稳定性能，单电极比电容达到505 F·g^-1。     

光电催化降解活性艳红K-2BP中电解质NaCl和Na2SO4的作用研究

以TiO₂/Ti为阳极, Ti网为阴极, 研究了活性艳红K-2BP在NaCl和Na₂SO₄电解质中的降解情况, 深入探讨了两种电解质在光电催化降解染料中的作用, 研究了电解质浓度、溶液pH值的影响, 并讨论了在混合盐电解质存在下, 活性艳红K-2BP的降解行为. 研究表明, 以NaCl为电解质时, Cl^－会转化为氧化性很强的活性氯, 活性氯及光电的共同作用, 加速了染料的降解. 以Na₂SO₄为电解质时, SO₄^2－在光电的作用下将发生两类反应, 一部分SO₄^2－捕获光生空穴和HO•, 对光电催化降解染料起抑制作用; 另一部分SO₄^2－将发生反应生成H₂O₂, 对染料降解起促进作用. 关键词 光电催化; 活性艳红K-2BP; TiO₂/Ti电极; 电解质     

光电催化降解活性艳红K-2BP中电解质NaCl和Na2SO4的作用研究

以TiO₂/Ti为阳极, Ti网为阴极, 研究了活性艳红K-2BP在NaCl和Na₂SO₄电解质中的降解情况, 深入探讨了两种电解质在光电催化降解染料中的作用, 研究了电解质浓度、溶液pH值的影响, 并讨论了在混合盐电解质存在下, 活性艳红K-2BP的降解行为. 研究表明, 以NaCl为电解质时, Cl^－会转化为氧化性很强的活性氯, 活性氯及光电的共同作用, 加速了染料的降解. 以Na₂SO₄为电解质时, SO₄^2－在光电的作用下将发生两类反应, 一部分SO₄^2－捕获光生空穴和HO•, 对光电催化降解染料起抑制作用; 另一部分SO₄^2－将发生反应生成H₂O₂, 对染料降解起促进作用. 关键词 光电催化; 活性艳红K-2BP; TiO₂/Ti电极; 电解质     

一例由多齿席夫碱构筑的Tb2配合物的结构、荧光性质及生物活性

使用多齿希夫碱配体 H₄L(H₄L=N'',N″-((1E,1''E)-(1,10-菲咯啉-2,9-二酰基)双(亚甲基)双(2-羟基苯甲酰肼))与 Tb(acac)₃·2H₂O反应(acac^-=乙酰丙酮根),通过溶剂热法,设计并合成了一例结构新颖的双核铽配合物[Tb₂(L)(H₂L)]·2CH₃OH·CH₃CN (1),并研究了该配合物的结构、荧光性质及生物活性。单晶X射线衍射分析表明该配合物主要含有2个TbⅢ离子和2个失去不同质子的配体离子(L^4-和H₂L^2-)。中心Tb1和Tb2离子都是九配位的,其几何构型呈现扭曲的呼啦圈形。固体荧光实验测试结果表明：该配合物在室温下表现出Tb^Ⅲ离子的荧光特征发射峰。生物活性研究表明,与配体H₄L和稀土离子相比较,配合物具有更强的抗菌活性。采用紫外可见光谱法、循环伏安法、凝胶电泳法和荧光光谱法研究了该配合物与小牛胸腺DNA之间的相互作用,结果表明配合物主要以插入作用的方式与小牛胸腺DNA结合。     

微晶Na0.7MnO2.05的制备及其在水溶液中的充放电特性研究

利用十二核锰簇合物[Mn₁₂O₁₂(CH₃COO)₁₆(H₂O)₄]为前驱物,通过先碱解再灼烧的方法合成了一种钠锰氧化合物Na_0.7MnO_2.05。扫描电子显微镜(SEM)观察结果表明产物由微米级的扁平棒状晶体组成。电化学测试表明,Na_0.7MnO_2.05是一种性能比较优良的超级电容器电极材料。在0.5 mol·L^-1 Na₂SO₄电解质溶液中和0~0.8 V电位窗口范围内,具有良好的循环稳定性能,充放电速率为0.125A·g^-1时单电极比电容达121 F·g^-1。     

Sol-gel synthesis of K3InF6 and structural characterization of K2InC10O10H6F9, K3InC12O14H4F18 and K3InC12O12F18

K₃InF₆ is synthesized by a sol-gel route starting from indium and potassium acetates dissolved in isopropanol in the stoichiometry 1:3, with trifluoroacetic acid as fluorinating agent. The crystal structures of the organic precursors were solved by X-ray diffraction methods on single crystals. Three organic compounds were isolated and identified: K₂InC₁₀O₁₀H₆F₉, K₃InC₁₂O₁₄H₄F₁₈ and K₃InC₁₂O₁₂F₁₈. The first one, deficient in potassium in comparison with the initial stoichiometry, is unstable. In its crystal structure, acetate as well as trifluoroacetate anions are coordinated to the indium atom. The two other precursors are obtained, respectively, by quick and slow evaporation of the solution. They correspond to the final organic compounds, which give K₃InF₆ by decomposition at high temperature. The crystal structure of K₃InC₁₂O₁₄H₄F₁₈ is characterized by complex anions [In(CF₃COO)₄(OH_x)₂]^(5−2x)− and isolated [CF₃COOH_2−x]^(x−1)− molecules with x=2 or 1, surrounded by K⁺ cations. The crystal structure of K₃InC₁₂O₁₂F₁₈ is only constituted by complex anions [In(CF₃COO)₆]³⁻ and K⁺ cations. For all these compounds, potassium cations ensure only the electroneutrality of the structure. IR spectra of K₂InC₁₀O₁₀H₆F₉ and K₃InC₁₂O₁₂F₁₈ were also performed at room temperature on pulverized crystals.     

Structure Study of Bi2.5Na0.5Ta2O9 and Bi2.5Nam−1.5NbmO3m+3 (m=2-4) by Neutron Powder Diffraction and Electron Microscopy

The crystal structures of Bi_2.5Na_0.5Ta₂O₉ and Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=3,4) have been investigated by the Rietveld analysis of their neutron powder diffraction patterns (λ=1.470 Å). These compounds belong to the Aurivillius phase family and are built up by (Bi₂O₂)²⁺ fluorite layers and (A_m-1B_mO_3m+1)^2- (m=2-4) pseudo-perovskite slabs. Bi_2.5Na_0.5Ta₂O₉ (m=2) and Bi_2.5Na_2.5Nb₄O₁₅ (m=4) crystallize in the orthorhombic space group A2₁am, Z=4, with lattice constants of a=5.4763(4), b=5.4478(4), c=24.9710 (15) and a=5.5095(5), b=5.4783(5), c=40.553(3) Å, respectively. Bi_2.5Na_1.5Nb₃O₁₂ (m=3) has been refined in the orthorhombic space group B2cb, Z=4, with the unit-cell parameters a=5.5024(7), b=5.4622(7), and c=32.735(4) Å. In comparison with its isostructural Nb analogue, the structure of Bi_2.5Na_0.5Ta₂O₉ is less distorted and bond valence sum calculations indicate that the Ta-O bonds are somewhat stronger than the Nb-O bonds. The cell parameters a and b increase with increasing m for the compounds Bi_2.5Na_m-1.5Nb_mO_3m+3 (m=2-4), causing a greater strain in the structure. Electron microscopy studies verify that the intergrowth of mixed perovskite layers, caused by stacking faults, also increases with increasing m.     

La3Ru8B6 and Y3Os8B6, new members of a homologous series R(A)nM3n−1B2n

Two new compounds, La₃Ru₈B₆ and Y₃Os₈B₆, were synthesized by arc melting the elements. Their structural characterization was carried out at room temperature on as-cast samples by using X-ray diffractometry. According to X-ray single-crystal diffraction results these borides crystallize in Fmmm space group (no. 69), Z=4, a=5.5607(1) Å, b=9.8035(3) Å, c=17.5524(4) Å, ρ=8.956 Mg/m³, μ=25.23 mm⁻¹ for La₃Ru₈B₆ and a=5.4792(2) Å, b=9.5139(4) Å, c=17.6972(8) Å, ρ=13.343 Mg/m³, μ=128.23 mm⁻¹ for Y₃Os₈B₆. The crystal structure of La₃Ru₈B₆ was confirmed from Rietveld refinement of X-ray powder diffraction data. Both La₃Ru₈B₆ and Y₃Os₈B₆ compounds are isotypic with the Ca₃Rh₈B₆ compound and their structures are built up from CeCo₃B₂-type and CeAl₂Ga₂-type structural fragments taken in ratio 2:1. They are the members of structural series R(A)_nM_3n−1B_2n with n=3 (R is the rare earth metal, A the alkaline earth metal, and M the transition metal). Structural and atomic parameters were also obtained for La_0.94Ru₃B₂ compound from Rietveld refinement (CeCo₃B₂-type structure, P6/mmm space group (no. 191), a=5.5835(9) Å, c=3.0278(6) Å).     

Composition-induced phase transition in Ca14Zn6−xGa10+xO35+x/2 (x=0.0 and 0.5)

Novel complex oxides Ca₁₄Zn₆Ga₁₀O₃₅ and Ca₁₄Zn_5.5Ga_10.5O_35.25 were prepared in air at 1200 °C, 72 h. Refinements of their crystal structures using X-ray powder diffraction data showed that Ca₁₄Zn₆Ga₁₀O₃₅ is ordered (S.G. F23, =0.0458, R_p=0.0485, R_wp=0.0659, χ²=1.88) and Ca₁₄Zn_5.5Ga_10.5O_35.25 disordered (S.G. F432, =0.0346, R_p=0.0601, R_wp=0.0794, χ²=2.82) variants of the crystal structure of Ca₁₄Zn₆Al₁₀O₃₅. In the crystal structure of Ca₁₄Zn₆Ga₁₀O₃₅, there are large empty voids, which could be partially occupied by additional oxygen atoms upon substitution of Zn²⁺ by Ga³⁺ as in Ca₁₄Zn_5.5Ga_10.5O_35.25. These oxygen atoms are introduced into the crystal structure of Ca₁₄Zn_5.5Ga_10.5O_35.25 only as a part of four tetrahedra (Zn, Ga)O₄ groups sharing common vertex. This creates a situation where even a minor change in the chemical composition leads to considerable anion and cation disordering resulting in a change of space group from F23 (no. 196) to F432 (no. 209).     

The crystal chemistry of Bi6TP2O15+x, T=Fe, Ni, Zn: Isomorphism and polymorphism, structural relationship to Bi6TiP2O16

The crystal structures of compounds with nominal compositions Bi₆FeP₂O_15+x (I), Bi₆NiP₂O_15+x (II) and Bi₆ZnP₂O_15+x (III) were determined from single-crystal X-ray diffraction data. They are monoclinic, space group I2, Z=2. The lattice parameters for (I) are a=11.2644(7), b=5.4380(3), c=11.1440(5) Å, β=96.154(4)°; for (II) a=11.259(7), b=5.461(4), c=11.109(7) Å, β=96.65(1)°; for (III) a=19.7271(5), b=5.4376(2), c=16.9730(6) Å, β=131.932(1)°. Least squares refinements on F² converged for (I) to R1=0.0554, wR₂=0.1408; for (II) R₁=0.0647, wR₂=0.1697; for (III) R₁=0.0385, wR₂=0.1023. The crystals are complexly twinned by 2-fold rotation about , by inversion and by mirror reflection. The structures consist of edge-sharing articulations of OBi₄ tetrahedra forming layers in the a-c plane that then continue by edge-sharing parallel to the b-axis. The three-dimensional networks are bridged by Fe and Ni octahedra in (I) and (II) and by Zn trigonal bipyramids in (III) as well as by oxygen atoms of the PO₄ moieties. Bi also randomly occupies the octahedral sites. Oxygen vacancies exist in the structures of the three compounds due to required charge balances and they occur in the octahedral coordination polyhedron of the transition metal. In compound (III), no positional disorder in atomic sites is present. The Bi-O coordination polyhedra are trigonal prisms with one, two or three faces capped. Magnetic susceptibility data for compound (I) were obtained between 4.2 and 350 K. Between 4.2 and 250 K it is paramagnetic, μ_eff=6.1 μ_B; a magnetic transition occurs above 250 K.     

Li2O-TiO2-SiO2-P2O5和Li2O-TiO2-Al2O3-P2O5体系锂离子固体电解质的制备及性能研究

一些具有NASICON型网格结构的固体电解质具有高的电导率和好的稳定性,NASICON的意思是Na Super Ionic Conductor[1]。当NaZr2(PO4)3中P5 被Si4 部分取代时便可以得到具有NASICON结构的Na1 xZr2SixP3-xO12体系,其具有高的钠离子电导率。然而有相同结构的Li1 xZr2SixP3-xO12体系的离子电导率却很低,这是因为Li 半径太小,而NASICON三维网格结构的离子通道太大,两者不匹配而使电导率下降[2]。但当LiZr2(PO4)3中Zr4 被离子半径小些的Ti4 取代,所得LiTi2(PO4)3的通道就与Li 半径相匹配,适合于锂离子的迁移,从而使其电导率…     

Synthesis and structural characterization of Al7C3N3-homeotypic aluminum silicon oxycarbonitride, (Al7−xSix)(OyCzN6−y−z) (x∼1.2, y∼1.0 and z∼3.5)

A new aluminum silicon oxycarbonitride, (Al_5.8Si_1.2)(O_1.0C_3.5N_1.5), has been synthesized and characterized by X-ray powder diffraction (XRPD), transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX) and electron energy loss spectroscopy (EELS). The title compound is hexagonal with space group P6₃/mmc and unit-cell dimensions a=0.322508(4) nm, c=3.17193(4) nm and V=0.285717(6) nm³. The atom ratios of Al:Si and those of O:C:N were, respectively, determined by EDX and EELS. The initial structural model was successfully derived from the XRPD data by the direct methods and further refined by the Rietveld method. The crystal is most probably composed of four types of domains with nearly the same fraction, each of which is isotypic to Al₇C₃N₃ with space group P6₃mc. The existence of another new oxycarbonitride (Al_6.6Si_1.4)(O_0.7C_4.3N_2.0), which must be homeotypic to Al₈C₃N₄, has been also demonstrated by XRPD and TEM.     

A new 2212-type stair like structure: Bi14Sr21Fe12O61, m=5 member of the generic [Bi2Sr3Fe2O9]m[Bi4Sr6Fe2O16] family

A new oxide, Bi₁₄Sr₂₁Fe₁₂O_61, with a layered structure derived from the 2212 modulated type structure Bi₂Sr₃Fe₂O₉, was isolated. It crystallizes in the I2 space group, with the following parameters: a=16.58(3) Å, b=5.496(1) Å, c=35.27(2) Å and β=90.62°. The single crystal X-ray structure determination, coupled with electron microscopy, shows that this ferrite is the m=5 member of the [Bi₂Sr₃Fe₂O₉]_m[Bi₄Sr₆Fe₂O₁₆] collapsed family. This new collapsed structure can be described as slices of 2212 structure of five bismuth polyhedra thick along , shifted with respect to each other and interconnected by means of [Bi₄Sr₆Fe₂O₁₆] slices. The latter are the place of numerous defects like iron or strontium for bismuth substitution; they can be correlated to intergrowth defects with other members of the family.     

Non-centrosymmetric Ba3Ti3O6(BO3)2

The compound previously reported as Ba₂Ti₂B₂O₉ has been reformulated as Ba₃Ti₃B₂O₁₂, or Ba₃Ti₃O₆(BO₃)₂, a new barium titanium oxoborate. Small single crystals have been recovered from a melt with a composition of BaTiO₃:BaTiB₂O₆ (molar ratio) cooled between 1100°C and 850°C. The crystal structure has been determined by X-ray diffraction: hexagonal system, non-centrosymmetric space group, a=8.7377(11) Å, c=3.9147(8) Å, Z=1, wR(F²)=0.039 for 504 unique reflections. Ba₃Ti₃O₆(BO₃)₂ is isostructural with K₃Ta₃O₆(BO₃)₂. Preliminary measurements of nonlinear optical properties on microcrystalline samples show that the second harmonic generation efficiency of Ba₃Ti₃O₆(BO₃)₂ is equal to 95% of that of LiNbO₃.     

一维纳米Co_3O_4,Ag/Co_3O_4及CuO/Co_3O_4的合成与电催化性能(英文)

采用水热合成法制备了Co3O4及复合Ag/Co3O4、CuO/Co3O4一维纳米产品。用XRD,FE-SEM和TEM手段对产品进行了表征。采用循环伏安法研究了合成产品修饰的玻碳电极在碱性溶液中对对硝基苯酚的电催化还原性能。与裸玻碳电极相比,1mmol·L-1的对硝基苯酚在用Co3O4、特别是CuO/Co3O4修饰的玻碳电极上还原的峰电流明显增大,用Ag/Co3O4(Ag/Co原子比分别为1∶5和2∶5)修饰的玻碳电极催化还原对硝基苯酚时,尽管还原峰电流增大不是太大,但其峰电位明显降低(分别降低0.265和0.371V)。