酞菁锌掺杂二氧化硅凝胶基质的光谱学特征

利用溶胶凝胶技术将四磺化酞菁锌 (ZnPcS4)成功地引入到了二氧化硅凝胶基质中 ,制备了均匀掺杂的有机 /无机复合干凝胶。研究ZnPcS4分子在溶胶凝胶过程中紫外可见吸收光谱的变化规律以探索其在复合体系中的存在状态。实验表明 ,在溶胶阶段 ,随着时间的延长 ,紫外可见吸收光谱中单体的吸收峰强度增大 ,说明凝胶中酞菁单体的浓度增大 ;而形成凝胶后 ,随着时间的延长 ,紫外可见吸收光谱中单体的吸收峰强度减小 ,二聚体的吸收峰强度增大 ,说明由于体系结构和微化学环境的变化 ,酞菁分子趋向于聚合。     

Aggregation and spectral properties of Mg(II) tetracarboxyphthalocyanine in aqueous solutions and solid xerogels

Based on spectroscopic studies of magnesium(II) tetracarboxyphthalocyanine molecules in liquid solutions, we have determined the role of the carboxyl groups and the aqueous medium during formation of associates. We have shown that the Q band of the associated form is split into two components of frequency separated by ∼250 cm⁻¹. The effect of the nature of the gel matrices on the spectral luminescence properties of magnesium(II) tetracarboxyphthalocyanine has been studied by incorporating the pigment into a series of xerogels differing in the chemical structure of the inorganic framework and the nanopore surface area. We discuss the reasons for the appearance of associated forms of the pigment in different xerogels. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 211–217, March–April, 2007.     

Effect of Pr3+ Doping on the OH Content of Silica Xerogels

Pr2O3-SiO2 xerogels doped with different Pr/Si concentrations were annealed at 900°C for 120 h and then investigated by FTIR, NIR absorption, Raman and luminescence spectroscopies. It is observed that the content of surface silanol groups is lower for higher Pr3+ concentrations. Luminescence measurements indicate that the amount of the residual OH plays an important role in the spectroscopic properties of the Pr3+ ion and in particular the quantum yield of the emission from the 3P0,1 and 1D2 states.     

镍基气凝胶催化CH_4-CO_2重整制取合成气反应的研究 Ⅰ.制备方法对NiO-CeO_2-Al_2O_3催化剂物化性质的影响

采用浸渍法、溶胶 凝胶过程与普通干燥、超临界干燥过程相结合的方法制备了具有不同结构特点的NiO CeO2 Al2 O3催化剂 ,分别为浸渍型催化剂 (iNCA)、干凝胶催化剂 (xNCA)和气凝胶催化剂 (aNCA) ,利用BET、TEM、XRD、TPR、NH3 TPD、H2 TPD等方法对各催化剂样品的物化性质进行了考察。研究结果表明 ,经 82 3K焙烧后 ,镍含量为 9%的各催化剂样品中镍物种均分散良好 ;与iNCA相比 ,以溶胶 凝胶法为基础制备的xNCA和aNCA中镍物种与载体的相互作用强并且存在状态均一 ;三种催化剂中 ,气凝胶样品具有比表面积高、堆密度低、表面酸中心数多及表面镍分散度高的特点。     

Formation of Li2O in a chemically Li-intercalated V2O5 xerogel

We studied the electronic structure of a chemically Li-intercalated V₂O₅ xerogel. The technique used in the study was V 2p and O 1s X-ray absorption spectroscopy (XAS). The V ions in the as-prepared V₂O₅ xerogel are mostly in a pentavalent V⁵⁺ state. The spectra show that the V ions are partially reduced to V⁴⁺ and V³⁺ states upon Li intercalation. The results also show that low Li intercalation (x<1) affects mostly O 2p–V 3d mixed states, whereas for higher Li intercalation (x>1), this mechanism saturates and leads to Li₂O formation.     

介孔硅基干凝胶的降解性及其生物相容性研究

本研究利用改进的溶胶-凝胶工艺合成了介孔硅基干凝胶。通过差热-热重(DTA-TG)、X-射线衍射(XRD)、红外光谱(FTIR)和N₂等温吸附-脱附测试分析,以及扫描电镜(SEM)、透射电镜(TEM)观察,表征了硅基干凝胶的热效应、相态、结构、形貌特征,并对合成的硅基干凝胶进行了体外降解与细胞培养实验研究。测试结果表明：合成的硅基干凝胶为平均孔径3nm左右、最大比表面积901 m²·g^-1的介孔结构。体外模拟体液(Simulated body fluid,SBF)降解结果显示,低温处理的材料在42 d内完全降解,直线拟合符合一级反应动力学方程。通过添加钙磷成分或高温煅烧处理可以调控干凝胶的降解速率,使硅基干凝胶的降解呈现直线式匀速降解的特征。体外细胞培养表明：硅基干凝胶可促进C2C12细胞(C3H小鼠肌原细胞)的分化和繁殖,证明材料的生物相容性良好。     

Synthesis, characterization, and catalytic properties of a mesostructured lamellar xerogel tungsten oxide phase

Cetyltrimethylammonium bromide (CTAB) and n-hexadecylamine (HDA) have been used as template in the synthesis of a mesolamellar xerogel tungsten oxide phase (WO₃/CTAB/HDA). The catalytic properties of the resulting material were investigated in the oxidation of cis-cyclooctene, styrene, and cyclohexane, using hydrogen peroxide (H₂O₂), terc-butyl hydroperoxide (t-BOOH), or m-chlorperbenzoic acid (m-CPBA) as oxygen transfer agent. In general, the catalytic results were comparable to those obtained with related systems, thus suggesting the potential application of this material as catalyst for epoxidation reactions.     

二氧化锡/碳气凝胶的制备与电化学性能研究

应用真空浸渍法制备二氧化锡/碳气凝胶的复合材料. XRD、BET、SEM及TEM等测试结果显示,二氧化锡纳米颗粒（5~10 nm）均匀地填充在碳气凝胶的孔道内部. 在100 mA/g的电流密度下经过100周次充放电测试,该材料的容量保持率为首次循环的61.9%.     

Supercritical,Freezing and Thermal Drying Process of Resorcinol‐Formaldehyde Polymer based Nano‐carbons and their Highly Loaded PtRu Anode Electrocatalyst for DMFC

The capillary condensation is affected by micropore and nanopore of catalyst layer on fuel cell. Due to limitation of sluggish mass transport and electrocatalytic activity, to retain the pore skeleton of carbon and metal nanoparticles are very significant for enhanced utilizations of pore structure in electrochemical reaction. Besides, thickness of electrocatalyst layer is very crucial due to one of the factor affected by cell performance of direct methanol fuel cell. Highly loaded four Pt?Ru anode catalysts supported on resorcinol‐formaldehyde (RF) polymer based on meso‐porous carbons (80 wt.% Pt?Ru/carbon cryogel, 80 wt.% Pt?Ru/carbon xerogel and 80 wt.% Pt?Ru/carbon aerogel) and conventional carbon (80 wt.% Pt?Ru/Vulcan XC‐72) were prepared by colloidal method for direct methanol fuel cell. These catalysts were characterized by X‐Ray diffraction (XRD), High resolution transmission electron microscopy (HR‐TEM) and X‐ray photoemission (XPS). The results of CO stripping voltammetry, cyclic voltammetry (CV) and single cell test performed on DMFC show that Pt?Ru/carbon cryogel and Pt?Ru/carbon aerogel exhibits better performances in comparison to Pt?Ru/carbon xerogel and Pt?Ru/Vulcan XC‐72. It is thus considered that particle size, oxidation state of metal and electrochemical active surface area of these catalysts are important role in electrocatalytic activity in DMFC.