Degradability and Clearance of Silicon,Organosilica, Silsesquioxane,Silica Mixed Oxide,and Mesoporous Silica Nanoparticles

The biorelated degradability and clearance of siliceous nanomaterials have been questioned worldwide, since they are crucial prerequisites for the successful translation in clinics. Typically, the degradability and biocompatibility of mesoporous silica nanoparticles (MSNs) have been an ongoing discussion in research circles. The reason for such a concern is that approved pharmaceutical products must not accumulate in the human body, to prevent severe and unpredictable side‐effects. Here, the biorelated degradability and clearance of silicon and silica nanoparticles (NPs) are comprehensively summarized. The influence of the size, morphology, surface area, pore size, and surface functional groups, to name a few, on the degradability of silicon and silica NPs is described. The noncovalent organic doping of silica and the covalent incorporation of either hydrolytically stable or redox‐ and enzymatically cleavable silsesquioxanes is then described for organosilica, bridged silsesquioxane (BS), and periodic mesoporous organosilica (PMO) NPs. Inorganically doped silica particles such as calcium‐, iron‐, manganese‐, and zirconium‐doped NPs, also have radically different hydrolytic stabilities. To conclude, the degradability and clearance timelines of various siliceous nanomaterials are compared and it is highlighted that researchers can select a specific nanomaterial in this large family according to the targeted applications and the required clearance kinetics.     

Macroscale Colloidal Noble Metal Nanocrystal Arrays and Their Refractive Index‐Based Sensing Characteristics

Colloidal noble metal nanocrystals are promising for a large number of optical and biotechnological applications. Many practical applications require the formation of large‐area, high‐density, and uniformly distributed metal nanocrystal arrays on various substrates, to overcome the limitations brought by the instability of colloidal metal nanocrystal solutions and the high cost of single‐particle spectroscopy characterizations. A method is developed for directly depositing colloidal metal nanocrystals, including Au nanospheres, Au nanorods, Au nanobipyramids, and (Au core)/(Ag shell) nanorods, from their solutions onto different substrates. The resultant nanocrystal arrays are relatively uniform and dense, with the peak extinction value of a single layer reaching 0.3. Their areas are up to 10 cm by 10 cm and can be further increased if larger‐size containers are utilized. The refractive index sensitivities are studied for Au nanorod arrays supported on glass slides, mesoporous silica and titania films, and capped with different molecules. Au nanorods deposited on mesoporous titania films are found to exhibit the highest index sensitivities, comparable to those of the same nanorod sample in solutions. It is expected that this approach will greatly facilitate plasmonic applications that require large‐area arrays of noble metal nanocrystals.     

Ag和介孔碳改性Bi_2WO_6光催化剂的合成及其可见光下的光催化性能

采用水热法合成了花球状的Bi2WO6和介孔碳CMK-3/Bi2WO6的光催化剂,然后通过光还原得到了Ag负载的Ag/Bi2WO6和Ag-CMK-3/Bi2WO6,制备出可见光下具有高活性的光催化剂。利用紫外-可见漫反射光谱(UV-Vis DRS)、X射线衍射(XRD)、透射电子显微镜(TEM)、高分辨透射电子显微镜(HR-TEM)和扫描电子显微镜(SEM)对制备的样品进行表征,评价样品在可见光照射下降解亚甲基蓝(MB)的光催化活性。并研究了CMK-3和Ag负载在Bi2WO6上都能提高其光催化活性的机制。结果表明:CMK-3或Ag负载在Bi2WO6上都能大幅提高Bi2WO6的光催化活性,Ag-CMK-3/Bi2WO6光催化剂的光催化性能优于Ag/Bi2WO6和CMK-3/Bi2WO6光催化剂。     

A Brown Mesoporous TiO2‐x/MCF Composite with an Extremely High Quantum Yield of Solar Energy Photocatalysis for H2 Evolution

A brown mesoporous TiO_2‐x/MCF composite with a high fluorine dopant concentration (8.01 at%) is synthesized by a vacuum activation method. It exhibits an excellent solar absorption and a record‐breaking quantum yield (Φ = 46%) and a high photon–hydrogen energy conversion efficiency (η = 34%,) for solar photocatalytic H₂ production, which are all higher than that of the black hydrogen‐doped TiO₂ (Φ = 35%, η = 24%). The MCFs serve to improve the adsorption of F atoms onto the TiO₂/MCF composite surface, which after the formation of oxygen vacancies by vacuum activation, facilitate the abundant substitution of these vacancies with F atoms. The decrease of recombination sites induced by high‐concentration F doping and the synergistic effect between lattice Ti³⁺–F and surface Ti³⁺–F are responsible for the enhanced lifetime of electrons, the observed excellent absorption of solar light, and the photocatalytic production of H₂ for these catalysts. The as‐prepared F‐doped composite is an ideal solar light‐driven photocatalyst with great potential for applications ranging from the remediation of environmental pollution to the harnessing of solar energy for H₂ production.     

A Simple Aqueous Solution Based Chemical Methodology for Preparation of Mesoporous Alumina: Efficient Adsorbent for Defluoridation of Water

In this paper, we report a simple aqueous solution based chemical method for preparation of mesoporous γ-Al₂O₃ which can be used for removal of fluoride ions from water. The synthesized Al₂O₃ and commercial Al₂O₃(Grade AD101-F, ACE Manufacturing and Marketing, Baroda, India) were characterized by using powder x-ray diffractometer, N₂ adsorption–desorption surface area and pore size analyzer, and high resolution transmission electron microscope. Synthesized Al₂O₃ contains a wormhole-like mesoporous structure with 358.7 m² g^?1 Brunauer–Emmett–Teller (BET) surface area and 0.8 cm³ g^?1 pore volume. Batch adsorption studies were performed to determine the fluoride adsorption capacity of Al₂O₃. The effect of different parameters such as contact time, initial fluoride concentration, pH, and adsorbent dose was studied to understand the fluoride adsorption behavior of the synthesized Al₂O₃ under various conditions. The kinetics results showed that the fluoride adsorption on synthesized Al₂O₃ followed pseudo-second-order kinetics. Adsorption equilibrium data fitted well to the Freundlich equation and indicated multilayer adsorption of fluoride on the surface of Al₂O₃. Synthesized Al₂O₃ demonstrated significantly improved fluoride adsorption capacity and faster kinetics than commercial Al₂O_3.     

以聚乙二醇为模板凝胶转化制备介孔ZSM-5沸石及其催化性能

以聚乙二醇为介孔导向剂, 通过凝胶转化制备了介孔ZSM-5沸石。研究表明, 在TPA⁺/SiO₂=0.1时经过9~15 h溶剂挥发制得的凝胶, 在160℃处理24 h可得到介孔ZSM-5沸石; 挥发时间太短或太长会得到纯的ZSM-5沸石或介孔材料, 说明在凝胶的制备过程中, 通过控制溶剂的挥发程度, 既可为沸石生长过程提供所需的水分, 又能避免沸石晶体形成过程中无定型相的产生, 从而在较低的TPA⁺浓度下获得介孔ZSM-5沸石。与传统的ZSM-5沸石相比, 利用该方法制备的介孔ZSM-5沸石不仅具有微孔/介孔多级孔结构, 同时具有沸石材料较强的酸性、较高的水热稳定性和择形催化性能, 使其在苯甲醛与正丁醇的大分子醇醛缩聚反应中能有效地克服传统沸石孔径限制的缺点, 收率高达42.4%。     

Synthesis of MCM–41 mesoporous molecular sieves containing heteroatoms and their catalytic activity

采用水热合成法合成了金属原子(Zn, Ni, Fe, Al, Cu, Ce)掺杂的MCM--41介孔分子筛(简称T--MCM--41), 并将其应用于邻苯二甲酸二(2--乙基己)酯(DOP)的合成反应, 研究了不同原子的掺杂对T--MCM--41的结构、比表面积和孔径、酸性及催化性能的影响. 结果表明, 所制备的T--MCM--41仍然具有六方有序排列结构, 比表面积较高(550--900 m2/g)、孔径大(3 nm左右), 杂原子的引入使T--MCM--41产生了酸中心, 从而使其对DOP的合成具有很好的催化活性和选择性. 用T--MCM--41(T=Zn, Fe, Al, Cu)催化DOP的合成反应, 在5 h的反应时间内苯酐的转化率可以达到95.5%以上, DOP的选择性可达到96.5%以上. T--MCM--41催化剂具有很好的稳定性, Al--MCM--41在重复使用5次后仍具有较好的催化活性.     

MoS2/有序介孔碳复合材料的制备及性能研究

采用水热法合成了纯MoS2及MoS2/有序介孔碳复合材料(MoS2/OMC)。X射线衍射(XRD)、透射电子显微镜(TEM)、扫描电子显微镜(SEM)及循环伏安曲线(CV)等分别用来表征样品的结构、形貌及电化学性能。实验结果表明,以钼酸钠和硫脲分别为钼、硫源合成的MoS2/OMC复合材料的性能较纯MoS2有明显提升。MoS2/OMC复合材料的首次放电容量达到1247mAh/g,第二、三次的放电容量分别为948mAh/g、894mAh/g,容量保持率为94%。二、三次充、放电曲线的近乎重合及高倍率下的高放电容量,亦表明该复合电极有极佳的循环稳定性及良好的可逆性。     

基于低聚酰亚胺含氮介孔碳材料的制备

以低聚酰亚胺为氮源前驱体、交联酚醛树脂为碳源、嵌段共聚物为软模板剂,通过相分离自组装、交联和高温锻烧处理制备了新型高规整含氮介孔碳材料,并用FT-IR、SEM、TEM、热重分析和小角X光散射等测试方法表征介孔碳材料的组成与结构.结果表明,处理温度达350℃时嵌段共聚物模板可被成功移除,进而形成多孔结构;温度达600℃时体系完全碳化,可得到高规整的多孔含氮碳材料.通过调节体系中氮源、碳源及模板剂的相对比例可实现形貌由立方结构向柱状和层状结构的过渡,进而实现对含氮介孔材料形貌的有效调控.