The Structure of Zirconium Oxide in Silica Matrix and its Epoxidation Activity

Zirconia-silica composite oxides were prepared by a sol-gel method, and the state of Zr in the silica matrix was analyzed in relation to its activity in the epoxidation of oct-1-ene with t-butyl hydroperoxide. XAFS analysis suggested that Zr in the composite oxides with low Zr content was in the coordinatively less saturated state compared with those in the oxides with higher Zr contents. Epoxidation of oct-1-ene proceeded effectively on the oxides with low Zr contents. The first step of the epoxidation was assumed to be the interaction of t-butyl hydroperoxide with the coordinatively unsaturated site of Zr.     

相对活度在物理化学课程中的应用

介绍了相对活度的概念和化学势表达式的通式在物理化学课程中的一些应用,有助于学生深刻理解和系统掌握相关知识,对提高教师的授课效率和学生的学习效率均有一定的帮助。     

Pt的氧化状态对甲醇氧化活性的影响

采用NaBH4还原法制备了XC-72碳黑负载的Pt电催化剂,并在化学还原后用H2O2处理部分催化剂以改变Pt的氧化状态,以期改善Pt活性中心上水的离解而提高催化活性.X射线光电子能谱结果表明,经H2O2处理的催化剂含有较多的氧化态Pt.通过循环伏安法和记时电流法考察了经处理和未经处理的催化剂在酸性条件下的甲醇氧化的催化...     

Co/HZSM-5催化剂中Co的相态和价态表征及其与一步法合成苯乙烯活性之间的关系

金属的脱氢能力与其存在的价态和相态有很大关系.我们曾采用金属负载HZSM-5分子筛催化剂研究了苯和乙烯在无氧存在下一步合成苯乙烯的反应,发现Co/HZSM-5,Fe/HZSM-5和Zn/HZSM-5是较好的催化剂,并提出反应是经过中间物乙苯脱氢生成苯乙烯的机理^[1].魏铨等采用XPS技术对Co/HZSM-5催化剂中Co存在的相态和价态做了一些研究工作^[2].本工作结合XRD、TPR和DRS方法对不同温度下焙烧及还原的Co/HZSM-5中Co的相态和价态及其与一步法合成苯乙烯反应活性之间的关系进行了研究。     

Ni2+在γ-Al2O3上的分散状态及负载型Ni/γ-Al2O3催化剂的α-蒎烯加氢活性

用X-射线衍射(XRD)、紫外-可见漫散射光谱(UV-Vis DRS)、程序升温还原(TPR)、CO化学吸附和微反测试等方法研究了Ni²⁺在γ-Al₂O₃上的分散状态和负载型Ni/γ-Al₂O₃催化剂的α-蒎烯加氢催化活性。结果表明，当Ni²⁺负载量远低于其在γ-Al₂O₃载体表面分散容量时，Ni²⁺优先嵌入载体表面四面体空位，随着Ni²⁺负载量的增加，嵌入载体表面八面体空位Ni²⁺的比例增大。由于八面体Ni²⁺易被还原为金属态Ni⁰，NiO/γ-Al₂O₃样品的还原度随Ni²⁺负载量的增加而大幅度地增加，经氢还原所得Ni/γ-Al₂O₃催化剂的CO吸附量和α-蒎烯加氢催化活性大幅度增加。对La₂O₃助剂的作用进行了研究，结果表明分散在γ-Al₂O₃上的La³⁺物种可阻止Ni²⁺嵌入γ-Al₂O₃表面四面体空位，增大了八面体Ni²⁺物种所占比例，提高了催化剂的还原度，故Ni-La₂O₃/γ-Al₂O₃催化剂催化活性高于Ni/γ-Al₂O₃催化剂。     

铁酸镍纳米微粒的固相合成及其催化性能

微波辐射;乙苯脱氢;铁酸镍纳米微粒的固相合成及其催化性能     

稀土三元配合物的低热固相合成、表征及抑菌活性研究

首次在室温条件下通过固相反应制得了镧稀土水杨酸8-羟基喹啉三元配合物La(Hsal)2(hq)(hq=C9H6NO^-；Hsal^-=C7H5COO^-)。采用元素分析、红外光谱、X射线粉末衍射、热重-差热分析等手段对配合物进行了表征。同时还初步分析了固相反应的机理。抑菌实验表明该配合物对大肠杆菌、金黄色葡萄球菌、白色念珠菌、芽孢杆菌都有很好的抑菌效果。     

多金属氧酸盐纳米粉体室温固相合成、表征及催化性能

多金属氧酸盐纳米粉体室温固相合成、表征及催化性能;多金属氧酸盐;纳米粉体;固相合成;催化性能     

新型N-TiO2的固相法制备及其光催化性能

以纳米管钛酸为前驱体,以NH4HCO3为N源,先机械研磨使二者混合均匀,再在Ar保护下,于不同温度焙烧4h制得N掺杂TiO2 (N-TiO2),并采用X射线粉末衍射、X射线光电子能谱、紫外-可见吸收光谱、透射电镜及N2吸附-脱附对样品进行了表征.结果显示,N以间隙掺杂方式进入TiO2晶格内.在热处理过程中,生成中间体(...     

Controlling the Oxidation State of Pt Single Atoms for Maximizing Catalytic Activity

Single-atom catalysts (SACs) have emerged as promising materials in heterogeneous catalysis. Previous studies reported controversial results about the relative level in activity for SACs and nanoparticles (NPs). These works have focused on the effect of metal atom arrangement, without considering the oxidation state of the SACs. Here, we immobilized Pt single atoms on defective ceria and controlled the oxidation state of Pt SACs, from highly oxidized (Pt⁰: 16.6 at %) to highly metallic states (Pt⁰: 83.8 at %). The Pt SACs with controlled oxidation states were then employed for oxidation of CO, CH₄, or NO, and their activities compared with those of Pt NPs. The highly oxidized Pt SACs presented poorer activities than Pt NPs, whereas metallic Pt SACs showed higher activities. The Pt SAC reduced at 300 °C showed the highest activity for all the oxidations. The Pt SACs with controlled oxidation states revealed a crucial missing link between activity and SACs.     

Au掺杂方式对锐钛矿TiO2光催化性能的影响

结合超临界乙醇干燥技术, 采用沉积-沉淀(DP)和共沉淀(CP)法分别制备了具有单一锐钛矿晶相的Au/TiO2和Au(0.2%, 原子分数)-TiO2光催化剂, 通过XRD、BET、TEM、XPS和Raman手段表征样品中Au的掺杂形态, 以光催化降解甲基橙为模型反应考察了样品的光催化活性. 结果表明, DP法制备的Au/TiO2在110 ℃干燥处理后, 表面存在的Au3+能有效地促进锐钛矿TiO2光催化性能, 其一级反应速率常数比纯锐钛矿TiO2提高了3.2倍, 比商用光催化剂Degussa-P25提高了4.1倍, 而当Au3+被还原为Au0后光催化活性下降. 用CP法制备的Au-TiO2并没有较大地提高锐钛矿TiO2光催化性能, 在焙烧温度达到800 ℃时, Au向表面迁移聚集, 造成锐钛矿TiO2晶格氧空位和缺陷位增加, 使光催化活性下降.     

Novel Composite Plastics Containing Silver(I) Acylpyrazolonato Additives Display Potent Antimicrobial Activity by Contact

New silver(I) acylpyrazolonato derivatives displaying a mononuclear, polynuclear, or ionic nature, as a function of the ancillary azole ligands used in the synthesis, have been fully characterized by thermal analysis, solution NMR spectroscopy, solid‐state IR and NMR spectroscopies, and X‐ray diffraction techniques. These derivatives have been embedded in polyethylene (PE) matrix, and the antimicrobial activity of the composite materials has been tested against three bacterial strains (E. coli, P. aeruginosa, and S. aureus): Most of the composites show antimicrobial action comparable to PE embedded with AgNO₃. Tests by contact and release tests for specific migration of silver from PE composites clearly indicate that, at least in the case of the PE, for composites containing polynuclear silver(I) additives, the antimicrobial action is exerted by contact, without release of silver ions. Moreover, PE composites can be re‐used several times, displaying the same antimicrobial activity. Membrane permeabilization studies and induced reactive oxygen species (ROS) generation tests confirm the disorganization of bacterial cell membranes. The cytotoxic effect, evaluated in CD34⁺ cells by MTT (3‐(4,5‐dimethylthiazole‐2‐yl)‐2,5‐diphenyltetrazoliumbromide) and CFU (colony forming units) assays, indicates that the PE composites do not induce cytotoxicity in human cells. Studies of ecotoxicity, based on the test of Daphnia magna, confirm tolerability of the PE composites by higher organisms and exclude the release of Ag⁺ ions in sufficient amounts to affect water environment.     

Reducing Packing Factor of ZnIn2S4 to Promote Photocatalytic Activity

Due to the quite sluggish charge-carrier separation in semiconductor photocatalysts, the photocatalytic activity of these materials is still far inferior than anticipated. Herein, a novel approach to reducing the packing factor(PF) of ZnIn₂S₄ semiconductors to improve the charge-carrier separation is offered. The well-crystallized Zn_1-xIn₂S_4-x(x=0, 0.05, 0.1) powders were productively prepared through solid-state reactions. Their structures were verified by the high-resolution transmission electron microscopy, powder X-ray diffraction, and X-ray photoelectron spectroscopy. The PF values of Zn_1-xIn₂S_4-x(x=0, 0.05, 0.1) samples were calculated to be 0.683, 0.651, and 0.618, respectively. The reduction of the PF for Zn_1-xIn₂S_4-x with increasing x can promote the separation of photoexcited carriers, and this process was endorsed by their photoelectric response and photoluminescence emission spectra. The Zn_0.9In₂S_3.9 sample with a lower PF value presents roughly 21 times higher photocurrent density and four times higher photodegrading rate of methyl orange than those of pristine ZnIn₂S₄.     

OCS分子单重态和三重态结构的密度泛函理论研究

OCS是大气同温层中唯一的硫化物，与CS2、N2O和CO2等一样都是具有16个价电子的闭壳层分子，这些典型三原子分子的电子结构与性质一直为理论和实验工作者所关注。尽管它们只是简单的三原子分子，但仍有一些性质不为人所知。目前还未见有关OCS分子电子结构与性质的研究报道。     

Thermal Conductivity of Selenium Doped with Indium and Iodine in the Solid and Liquid States

Abstract

We have measured the thermal conductivity in both solid and liquid states for two amorphous samples. The first is selenium doped with indium and the second is selenium doped with iodine. The concentration of In and I in the samples were 50000 ppm. Measurements were taken in a temperature range from 1000 to 370°C, and were carried out using the concentric cylinder method, which is based on the flow of heat through a cylindrical wall.     

SBA‐15‐Oxynitrides as a Solid‐Base Catalyst: Effect of Nitridation Temperature on Catalytic Activity

Solid bases, such as SBA‐15‐oxynitrides, have attracted considerable interest for potential applications as catalysts in important industrial processes. Reported herein is that by simply tuning the temperature of nitridation (ammonolysis), the catalytic activity of these solid bases can be enhanced. Solid‐state NMR spectroscopy and XPS studies provided the reasoning behind this change in activity.     

固态化合物中铕的价态研究进展

介绍了近年来关于变价稀土元素Ｅｕ价态研究的最新进展,总结了Ｅｕ＾２＋的价态稳定和转换及其与基质结构,取代离子半径电荷,共掺杂稀土离子电子构型之间的关系和规律。     

High pressure in solid state chemistry: Combined experimental and modeling approaches for assessing and predicting properties

The thermodynamic pressure parameter has been thoroughly used with mastership by Gérard Demazeau throughout his rich career in solid state chemistry and materials sciences and more recently in biosciences. After a review of such works, focus is made in this topical article on his contribution together with his team in the field of hard materials based on light elements B, C, N with a proposition of a new ultra-hard carbon nitride C₂N on one hand and on the structural transformations under high pressures of perovskite into postperovskite with a change of dimensionality from 3D to 2D and related oxides, regarding the arrangement of octahedra, on the other hand. Investigation and concepts first arising from experimental observables are shown to be aided and accelerated via first principles calculations of energy and energy-related quantities.