二氧化钛柱撑层状氧化锰微孔材料的合成及表征

Na型层状锰氧化物于0.1 mol/L HCl 溶液中离子交换制得前驱体H型层状锰氧化物. H型层状锰氧化物在十二胺乙醇溶液中反应得到层间距为2.62 nm的中间产物——十二胺插入的层状锰氧化物, 该中间产物在异丙醇钛和乙醇的混合溶液中溶剂热处理得到层间距为1.24 nm的钛酸柱撑层状锰氧化物. 在300 ℃条件下经2 h焙烧得到二氧化钛铸型氧化锰微孔材料. 应用XRD, DSC-TGA, SEM, TEM, IR, 氮气吸附实验及元素分析进行了不同阶段所得试样的分析表征. 结果表明十二胺分子在锰氧层间的最大插入量为2.2 mmol/g, 异丙醇钛分子的置换插入生成了组成为Mn_7.00Ti_1.74O_23.3(C₁₂H₂₅NH₂)_0.52•1.93H₂O的铸型层状锰氧化物. 300 ℃焙烧处理所得二氧化钛铸型氧化锰微孔材料的比表面积为140 m²/g.     

精氨酸插层氧化锰纳米结构材料的制备和表征

应用氧化法水热合成了Na型层状氧化锰[BirMO(Na)], 通过离子交换反应在0.1 mol/L HCl溶液中Na型层状氧化锰转化成H型层状氧化锰[BirMO(H)]. BirMO(H)在四甲基氢氧化铵[(CH3)4NOH]溶液中搅拌处理7 d后, 剥离生成了MnO2纳米层胶体分散液. 剥离的MnO2纳米层胶体分散液在pH＝4.0～11.0的精氨酸溶液中搅拌2 d, 得到了层间距为1.49 nm的精氨酸插层氧化锰纳米结构材料. 通过XRD, DSC-TGA, SEM, IR及元素分析对合成试样进行了分析表征. 结果表明精氨酸在氧化锰层间的插入量及插入形式与重组溶液的pH值密切相关, 其最大插入量为1.80 mmol/g.     

Intrinsic emission and tunable phosphorescence of perfluorosulfonate ionomers with evolved ionic clusters

Intrinsic emission from unorthodox luminogens without traditional conjugated building blocks is drawing increasing attention.However, the emission mechanism is still controversial. Herein, we demonstrate the intriguing emission from perfluorosulfonate ionomers(PFSIs), which can be explained by the clustering triggered emission(CTE) mechanism. Despite being free of any conventional chromophores, PFSIs exhibit bright emission and multi-color phosphorescence(77 K) in concentrated solutions,powders and membranes with obvious aggregation-induced emission(AIE) characteristics. Clustered sulfonic acids are responsible for the light emission, and their connection and evolution are deeply explored via X-ray diffraction(XRD) and small angel X-ray scattering(SAXS), in which the electron overlap determined by the clustered status results in the extended conjugation and simultaneously rigidified conformations. These results demonstrate that it is feasible to use fluorescence analysis to explore the ionic cluster structure and evolution of PFSI, and it can be applied in the pure organic luminescent field as well.     

柠檬酸溶胶凝胶法制备LiCoO_2电极材料及其表征

目前研究较多的锂离子电池正极材料主要有LiCoO2、LiNiO2和LiMn2O4犤1犦,虽然LiCoO2的成本相对较高,但LiCoO2具有最为优良的电化学性能,如高且平稳的充放电平台、高比容量以及良好的循环性能犤2犦,是目前应用最广泛的商品化电极材料。LiCoO2材料主要采用高温固相法犤3～5犦制备,该方法工艺简单,容易实现大规模生产,但缺点是需要较高的焙烧温度和较长的焙烧时间,且反应原料混合均匀程度有限,易导致非化学计量、非均相以及不规则的颗粒形貌等,因此材料的比容量、循环寿命等电化学性能以及反应的可控性还不甚理想。研究表明犤6犦电极材…     

Synthesis and evaluation of 5-thio-L-fucose-containing oligosaccharide

5-Thio-L-fucose-containing trisaccharide H-type II was synthesized. The 3',4'-O-isopropylidene-2-azido-2-deoxylactoside derivative, which was prepared from lactose by azidonitration of lactal, was used as a starting material. By regio- and stereoselective 5-thio-L-fucosylation of the 6,6'-dibenzoate 5 with 5-thiofucosyl trichloroacetimidate 6 and subsequent deprotection gave the 5-thio-L-fucose-containing H-type II 1. Conformational analysis of the 5-thio-L-fucose-containing H-type II and the native H-type II was carried out through NOESY experiments. The observed NOE values between N-acetylglucosamine and galactose, and galactose and fucose were same for these two trisaccharides. However, NOE values between fucose and N-acetylglucosamine were significantly different. Binding of the 5-thio-L-fucose-containing H-type II to lectins and antibodies were in some case stronger and in some case weaker than those of the native trisaccharide.     

Thermal behavior of silicophosphate gels obtained from different precursors

Phosphosilicate glasses are of great interest in important fields, such as optical active systems, energy generating systems, humidity sensors, and as materials for biomedical applications. Many studies were accomplished to establish the influence of different reaction parameters on the evolution and final structure of sol–gel prepared phosphosilicate gels. In the present work, we studied the thermal behavior of the silicophosphate gels obtained starting with different phosphorous precursors, the influence of these precursors on the composition and structure of the resultant gels, and their evolution with thermal treatment. By Fourier transform infrared spectroscopy (FT-IR), thermogravimetric and thermodifferential analysis (DTA/TG), and Differential Scanning calorimetry coupled with Mass Spectrometry (DSC-MS), it was established that the type of the precursors essentially influences the composition and structure and consequently the thermal behavior of the obtained gels. In the case of triethylphosphate precursor, all used methods of investigation have shown that the ester is trapped in the silica matrix and it is eliminated during the thermal treatment. Triethylphosphite partially hydrolizes and reacts with the silica network during post-preparation thermal treatment. Only in the case of H₃PO₄, an interaction with TEOS takes place and leads to Si–O–P bond formation. By thermal treatment, the gels with different composition and structure lead to materials with different properties.     

NH4^＋改型钾丝光沸石及其离子交换性

用铵盐改型钾丝光沸石,通过Ｘ－射线衍射,红外分析,分配系数,离子交换等温线及交换容量等的测定,就其结构及交换性能进行了研究;并与铵改型钠丝光沸石和天然斜发沸石等进行比较,表明ＮＨ４＾＋改型后的钾丝光沸石对Ｋ＾＋具有较高的交换容量和较好的Ｋ＾＋／Ｎａ＾＋分离效果。     

NH_4~ 改型钾丝光沸石及其离子交换性

用铵盐改型钾丝光沸石，通过Ｘ－射线衍射、红外分析、分配系数、离子交换等温线及交换容量等的测定，就其结构及交换性能进行了研究；并与铵改型钠丝光沸石和天然斜发沸石等进行比较，表明ＮＨ_4~ 改型后的钾丝光沸石对Ｋ~ 具有较高的交换容量和较好的Ｋ~ ／Ｎａ~ 分离效果。     

Effect of the thermal treatment conditions on the formation of zinc ferrite nanocomposite, ZnFe2O4, by sol–gel method

Zinc ferrite nanocomposite was synthesized via thermal decomposition of zinc acetate and iron nitrate at three different temperatures (350, 450, and 550 °C). The influence of the thermal decomposition of precursors on the formation zinc ferrites was studied by differential thermal gravimetry and thermogravimetry (TG). The TG curve shows two steps for the thermal decomposition with mass loss of 17.3 % at 78 °C and 63.3 % at 315 °C. The prepared zinc ferrites nanocomposite was characterized by X-ray diffraction and scanning electron microscopy. The X-ray diffractograms of ZnFe₂O₄ shows that a crystalline phase, spinel system is formed. SEM micrograph of the zinc ferrite nanocomposite indicates the formation of uniformly spherical 48-nm nanograins. The properties of the zinc ferrite phase were strongly dependent on their calcinations temperature and molar ratio of precursors.     

Phenol vs water molecule interacting with various molecules: Sigma-type, pi-type, and chi-type hydrogen bonds, interaction energies, and their energy components

The nature of interactions of phenol with various molecules (Y = HF, HCl, H2O, H2S, NH3, PH3, MeOH, MeSH) is investigated using ab initio calculations. The optimized geometrical parameters and spectra for the global energy minima of the complexes match the available experimental data. The contribution of attractive (electrostatic, inductive, dispersive) and repulsive (exchange) components to the binding energy is analyzed. HF favors sigma O-type H-bonding, while H2O, NH3, and MeOH favor sigma H-type H-bonding, where sigma O-/sigma H-type is the case when a H-bond forms between the phenolic O/H atom and its interacting molecule. On the other hand, HCl, H2S, and PH3 favor pi-type H-bonding, which are slightly favored over sigma O-, sigma H-, sigma H-type bonding, respectively. MeSH favors chi H-type bonding, which has characteristics of both pi and sigma H. The origin of these conformational preferences depending on the type of molecules is elucidated. Finally, phenol-Y complexes are compared with water-Y complexes. In the water-Y complexes where sigma O/sigma H-type involves the H-bond by the water O/H atom, HF and HCl favor sigma O-type, H2O involves both sigma O-/sigma H-type, and H2S, NH3, PH3, MeOH, and MeSH favor sigma H-type bonding. Except for HF, seven other species have larger binding energies with a phenol molecule than a water molecule.     

Investigation of thermal decomposition of yttrium–aluminum-based precursors for YAG phosphors

Three types of precursors were prepared using the wet-chemical synthesis route, starting from yttrium?Ceuropium?Caluminum nitrate solution and different precipitating agents (urea, oxalic acid, and ammonium carbonate). The precursors were fired at 1200?°C in nitrogen atmosphere in order to obtain europium-doped yttrium aluminate Y₃Al₅O₁₂:Eu³⁺ phosphor with garnet structure (YAG:Eu). The processes involved in the thermal decomposition of precursors and their composition were put in evidence using thermal analysis (TG?CDTA) and FT-IR spectroscopy. The GA?CDTA curves possess typical features for basic-oxalate, -nitrate, and -carbonates as formed with oxalic acid, urea, and ammonium carbonate, respectively. Correlation between the thermal decomposition steps, mass loss, and composition of gases evolved during the thermal treatment was established using TG?CDTA?CFT-IR coupling. It was found that the different composition of precursors reflects on the luminescent characteristics of the corresponding phosphors. Urea and ammonium carbonate lead to the formation of YAG type phosphors, with garnet structure and specific red emission. As for the oxalic acid, this precipitating agent generates a non-homogeneous powder that contains yttrium oxide as impurity phase. This phosphor is a mixture of Y₂O₃:Eu³⁺, Y₄Al₂O₉:Eu³⁺, and Y₃Al₅O₁₂:Eu³⁺ that explain the relative higher emission intensity.     

Thermal degradation of metal novolak precursors for high temperature superconductors: thermogravimetric and mass spectroscopy studies

High temperature superconductor (HTS) materials were prepared from novolak metal precursors in a special annealing process. In the present paper the thermal behaviour of pure cresol novolaks and novolak metal salt (nitrate) precursors was investigated by means of simultaneous thermogravimetric analysis and mass spectroscopy in air. The results show significant differences in thermal stability between the pure novolaks and the novolak metal precursors, with respect to the process as well as the products of decomposition. The main volatile products for the precursors are CO₂, H₂O and NO, thus indicating that the thermal degradation results in the formation of metal oxides at a temperature of about 300 °C.     

Self-assembly behaviors of the cholesteryl trimeric-phenylene vinylene derivative in the H2 O/THF system简

Cholesteryl trimeric phenylene vinylene(Chol-TPV) has been synthesized and characterized. The selfassembly behaviors of Chol-TPV in THF/H2 O system at different water content(water content: 40% and 80%) and different solute concentration(solute concentration: 1.0 10 5mol/L and saturated concentration) were studied using UV–vis spectrophotometry, photoluminescence spectrophotometry, and circular dichroism spectroscopy. Based on an analysis of the UV–vis and photoluminescence spectra, Chol-TPV shows the typical H-type aggregation at saturated concentration in 80% aqueous THF. However, Chol-TPV shows the non-typical H-type aggregation under other conditions. The circular dichroism signal suggests that the Chol-TPV exists in the right handed helical architectures with high water content at a concentration of 1.0 10 5mol/L, and a helix inversion was found at saturated concentration.     

Zn取代类水滑石衍生复合氧化物上N2O的催化分解

恒定二价与三价阳离子比为3((nZn+nMg)/nAl=3), 采用共沉淀法制备不同Zn含量的系列类水滑石前驱物ZnxMg3-xAl-HT (x=0, 0.5, 1.0, 1.5, 2.0, 2.5, 3.0), 经焙烧得到其衍生复合氧化物催化剂ZnxMg3-xAlO, 用于N2O的直接催化分解. 采用X射线衍射(XRD)、比表面积分析(Brunauer-Emmett-Teller)、热分析(TG-DSC)和傅里叶变换红外(FT-IR)光谱等表征手段考察了Zn含量对材料前驱物及其衍生复合氧化物组成和结构的影响, 研究了系列ZnxMg3-xAlO催化剂的N2O催化分解性能, 同时探讨了反应条件, 如N2O浓度、空速、O2和H2O等因素对催化剂活性的影响. 结果表明, 所有前驱物材料均能形成完整的层状水滑石结构; 经高温焙烧后形成了以Zn-Al尖晶石为主相的复合氧化物, 且Zn掺杂有助于促进尖晶石相的生成; Zn含量对材料的热稳定性、比表面积和N2O催化分解活性有显著的影响; 随着Zn含量增加, 催化剂比表面积下降, 但其不是影响催化剂活性的主要因素; 650 ℃焙烧后的Zn2.0Mg1.0AlO催化剂具有较好的N2O催化分解活性; N2O浓度、空速及O2对催化剂活性的影响较小, 而H2O则对活性有较大的影响.     

由不同镍盐前体制备高分散Ni/SBA-15催化剂：活化氛围的影响

以硝酸镍和乙酸镍为镍前体,用浸渍法分别在空气和氢气氛围活化制得系列Ni/SBA-15催化剂,通过XRD、H₂-TPD、N₂物理吸附和在线质谱等物理化学手段对催化剂进行了表征,并结合微型高压反应釜萘加氢反应,评价了催化剂的加氢性能。结果表明,氢气氛围活化对硝酸镍为镍前体所制Ni/SBA-15催化剂的镍分散度和活性有显著促进作用,而空气氛围活化对乙酸镍为镍前体所制催化剂有明显促进作用。根据催化剂前体在不同氛围活化时的热分解产物,提出了活化氛围对不同镍前体制得Ni/SBA-15催化剂所产生的作用机理。     

Facile synthesis and antimicrobial activity of manganese oxide/bentonite nanocomposites

Research on Chemical Intermediates - Manganese-oxide-intercalated bentonite clay (Mn3O4/BC) nanocomposites were synthesized via a thermal decomposition method using different precursors. The...     

The thermal behavior of some polymeric precursors used in CaAl12O19 synthesis

CaAl₁₂O₁₉ was synthesised using three different precursors: (a) a polyesteric type precursor resulted from the traditional Pechini method; (b) a polyesteric type precursor resulted from the reaction between citric acid and calcium and aluminum nitrates; and (c) a polymeric type precursor resulted from the reaction between acrylic acid and calcium an aluminum nitrates. The thermal behavior of the three precursors used in the CaAl₁₂O₁₉ synthesis was monitored to underline the thermal effects associated to the CaAl₁₂O₁₉ formation. Thermal analyses performed on precursors do not reveal clear differences regarding the thermal effects assigned to calcium aluminates formation, at temperatures over 800?°C. In contrast, thermal analysis of samples pre-fired at 200?°C, and especially at 600?°C, show clear differences between samples obtained in different ways. It is noted that in samples obtained from acrylic acid and nitrates, and citric acid and nitrates, CA₆ is practically single phase after calcination at 1,200?°C. However, in the sample obtained from citric acid, ethylene glycol, and nitrates, calcined at 1,200?°C, CA₆ is present along with CA₂ and ??-Al₂O₃.     

PtPd-nanoparticles supported by new carbon materials

Nanocomposites based on PtPd nanoparticles with chemical ordering like disordered solid solution on surface of multilayer graphene have been prepared through thermal shock of mechanically obtained mixture of double complex salt [Pd(NH₃)₄][PtCl₆] and different carbon materials–exfoliated graphite, graphite oxide and graphite fluoride. An effect of original carbon precursors on formation of PtPd bimetallic nanoparticles was studied using X-ray absorption spectroscopy (XAFS), transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was shown that the distribution of bimetallic nanoparticles over the multilayer graphene surface as well as the particles size distribution is controlled by the graphene precursors. For all nanocomposites, the surface of the nanoparticles was found to be Pd-enriched. In case when the thermal exfoliated graphite and graphite oxide were used as the graphene precursors a thin graphitized layer covered the nanoparticles surface. Such a graphitized layer was not observed in the nanocomposite, which used the fluorinated graphite as the precursor.     

Thin-film rotating disk electrode as a tool for comparing the activity of catalysts in the hydrogen oxidation reaction

A thin-film disperse rotating disk electrode is used to study the hydrogen oxidation reaction on platinum catalysts E-TEK with different purification degrees and on disperse palladium catalysts obtained from colloid solutions of organometallic complex precursors with subsequent thermal decomposition in an inert atmosphere or in hydrogen at diverse temperatures. Kinetic currents of the hydrogen oxidation reaction on these catalysts are determined at a potential of 0.025 V. The obtained values of currents may be utilized for performing a comparative estimation of the activity of various catalysts and the degree of their purification from the precursors or accidental impurities.     

烷基羧甲砜基氢氧化铁热脱羧和热分解法制备纳米氧化铁

十六烷基羧甲砜基氢氧化铁和丁基羧甲砜基氢氧化铁通过热脱羧方法,合成了纳米氧化铁颗粒。采用X射线衍射、红外光谱及透射电镜等手段对纳米氧化铁的合成过程和结构特征进行了表征。制备的纳米氧化铁具有8~18 nm的晶粒尺寸。羧甲砜基的热脱羧过程使得表面活性剂从纳米颗粒表面去除相对容易,特别是丁基羧甲砜基化合物。十六烷基羧甲砜基氢氧化铁制备纳米氧化铁颗粒存在脱羧有机分子还原Fe³⁺过程,而丁基羧甲砜基氢氧化铁通过热脱羧分解的方式合成纳米氧化铁颗粒。