Aromatization of n-butane over new LD-HBS catalysts. Effect of the gallium oxide support

It is shown that even pure quartz, other silicas or aluminas can enhance the aromatization activity of a ZSM-5 zeolite. Incorporation of gallium oxide onto these supports increases further the production of aromatics. The use of supported gallium oxide co-catalyst obtained by co-evaporation of a colloidal silica and a Ga salt has led to extremely high aromatization performance for the hybrid catalyst.     

Solid oxide solutions as catalysts —A comparison with supported Pt

The hydroformylation of olefins with the water soluble complex HRh(CO) [P(m-C₆H₄SO₃Na)₃]₃ (1) is dependent on the solubility of the olefins in the aqueous phase. In contrast, when the aqueous solution of1 is immobilized on a high surface area silica support the effects of the size of the olefins diminish. The immobilized catalyst1 on silica shows significant water loss but not rhodium leaching. It is proposed that the hydrophilic support holds the water soluble phosphines by hydrogen bonding of the hydrated sodium-sulphonate groups to the surface.     

Ractions of SiC with H2/H2O/Ar Mixtures at 1300°C

The reactions of a sintered α-SiC with 5% H₂/H₂O/Ar at 1300°C were studied. Thermomchemical modeling indicates that three reaction regions are expected, depending on the initial water vapor or equivalently oxygen content of the gas stream. A high oxygen content ( P (O₂) > 10⁻²² atm) leads to a SiO₂ formation. This generally forms as a protective film and limits consumption of the SiC (passive oxidation). An intermediate oxygen content (10⁻²² atm > P (O₂) > 10⁻²⁶ atm) leads to SiO and CO formation. These gaseous products can lead to rapid consumption of the SiC (active oxidation). Thermogravimetric studies in this intermediate region gave reaction rates which appear to be controlled by H₂O gas-phase transport to the sample and reacted microstructures showed extensive grain-boundary attack in this region. Finally, a very low oxygen content ( P (O₂) < 10⁻²⁶ atm) is thermochemically predicted to lead to selective removal of carbon and formation of free silicon. Experimentally low weight losses and iron silicides are observed in this region. The iron silicides are attributed to reaction of free silicon and iron impurities in the system.     

制备高质量ZnO光电薄膜的关键技术

提高ZnO薄膜的质量,使之适应制备光电器件的要求,是目前ZnO薄膜研究的一个主要问题。在对近年来人们在ZnO薄膜的制备上所作的工作进行调研的基础上,总结出对提高薄膜的质量有普遍参考价值的三种关键技术:“缓冲层”,“氢钝化”和“表面化学处理”。对三种关键技术的主要内容,及其在提高薄膜结晶质量与光电性能方面的效果和物理机制,作了较详细的介绍。并对这些技术提出了自己的一些见解。     

Indoline-based donor molecule for efficient co-evaporated organic photovoltaics

We demonstrated the use of an asymmetrical donor–acceptor-type indoline dye—D131, developed for dye-sensitized solar cells, as an electron donor and fullerene C₇₀ as an electron acceptor for thermal co-evaporated bulk-heterojunction organic solar cells (OSCs). In spite of the presence of intermolecular hydrogen bonds among D131 molecules, they can be thermally evaporated in high vacuum at a relatively low temperature of 220 °C. The blend ratio and thickness of the active layer of D131/C₇₀ blend films in OSCs were optimized to achieve a maximum power-conversion efficiency of 4.5% with a short-circuit current of 9.1 mA cm^?2, an open-circuit voltage of 0.89 V, and a fill factor of 0.56 under AM 1.5G solar illumination (100 mW cm^?2), which is the best value reported so far for OSCs based on indoline-based donor materials.     

3D Porous Cu Current Collectors Derived by Hydrogen Bubble Dynamic Template for Enhanced Li Metal Anode Performance

Lithium (Li) metal is the most ideal anode material for high‐energy density batteries. However, the high activity of Li metal, the large volume change, and Li dendrite formation during cycling hinder its practical application. Herein, 3D porous Cu synthesized through a simple time‐saving hydrogen bubble dynamic template method is used as a host for the improved performance Li metal anode. Contrary to the planar Cu foil, the synthesized 3D porous structure can reduce the local current density, suppress the mossy/dendritic Li growth, and buffer the volume change in the Li metal anode. Highly stable Coulombic efficiency is achieved at different specific current densities (0.5, 1, and 2 mA cm^?2) with a capacity of 1.0 mAh cm^?2. Moreover, symmetrical Li|Li‐3D Cu cells show more stable cyclic performance with a lower overpotential even at a high current density of 3 mA cm^?2.     

过氧化氢检测用新型BODIPY探针的设计合成与性能

为提高荧光探针对过氧化爆炸物的检测性能,以过氧化爆炸物信号分子过氧化氢(H_2O_2)作为检测对象,以苯偶酰为识别基团,二氟化硼二吡咯甲烷(BODIPY)为荧光团,设计合成了一种新型荧光探针4-(4-硝基苯偶酰基)-氟硼二吡咯甲烷(BD-3),并表征其化学结构、探讨其检测性能。BD-3自身仅有微弱的荧光,其最大吸收和发射波长分别为500 nm和508 nm。当BD-3响应H_2O_2之后,基于光致诱导电子转移(PET)机理,荧光强度增强11倍,发射出强烈的绿色荧光,并且裸眼可视。同时,BD-3对H_2O_2线性响应范围为1.0×10~(-6)~1.0×10~(-4)mol·L~(-1),相关系数R=0.9998,检出限为0.9μmol·L~(-1)。另外,BD-3对H_2O_2的检测表现出较好的光稳定性和高的选择性。该新型探针具有光稳定性好、选择性高及对H_2O_2的荧光增强响应等优点,可满足复杂环境条件下过氧化爆炸物的现场检测需求。     

Layer-transfer process for silicon-on-insulator with improved manufacturability

We observe hydrogen platelet buildup in single-crystalline silicon caused by hydrogen-plasma processing. The platelets are aligned along a layer of lattice defects formed in silicon before the plasma processing. The buried-defect layer is formed by either silicon-into-silicon or argon-into-silicon implantation. We discuss the platelet nucleation, growth, and merge phenomena and discuss applicability of the plasma hydrogenation to silicon-on-insulator (SOI) wafer fabrication by layer transfer.     

Improved Quantum Yield and Excellent Luminescence Stability of Europium‐Incorporated Polymeric Hydrogen‐Bonded Heptazine Frameworks Due to an Efficient Hydrogen‐Bonding Effect

Two of the most persistent challenges for the high‐end application of luminescent lanthanide (Ln) compounds are a low quantum yield and luminescence quenching caused by a liquid medium. In this work, a type of polymeric hydrogen‐bonded heptazine framework is developed incorporating trivalent europium ions (P‐HHF‐Eu) via a low‐cost and facile low‐temperature thermal condensation reaction. Structural characterization clearly reveals that the solid‐phase pyrolyzation reaction results in the formation of P‐HHF‐Eu. Using time‐resolved and steady state photoluminescence (PL) spectroscopies, the photophysics and photochemistry of P‐HHF‐Eu at different hydration degrees are investigated and the role of hydrogen bonding in the significant enhancement of the emission properties is demonstrated. Furthermore, the P‐HHF‐Eu particles suspended in polyvinyl alcohol hydrogel exhibit excellent luminescence stability with a high PL quantum yield of up to ≈46% and wavelength responsive color‐tunable emission, which holds potential for security applications.