Immobilization of Polymer-Stabilized Noble Metal Colloids and Their Catalytic Properties for Hydrogenation of Olefins

Polymer-stabilized noble metal colloids were efficiently immobilized on silica by the addition of organic acids under mild conditions. The function of organic acids in the immobilization was studied by infrared spectroscopy. Transmission electron micrographs indicate that the immobilized colloids have a controlled particle size and size distribution. They serve as catalysts in the hydrogenation of cyclohexene and cyclopentadiene, the results of which show that this new type of immobilized colloid has high selectivity and good stability.     

Improved Hydrogen‐Storage Thermodynamics and Kinetics for an RbF‐Doped Mg(NH2)2–2 LiH System

The introduction of RbF into the Mg(NH₂)₂–2 LiH system significantly decreased its (de‐)hydrogenation temperatures and enhanced its hydrogen‐storage kinetics. The Mg(NH₂)₂–2 LiH–0.08 RbF composite exhibits the optimal hydrogen‐storage properties as it could reversibly store approximately 4.76 wt % hydrogen through a two‐stage reaction with the onset temperatures of 80 °C for dehydrogenation and 55 °C for hydrogenation. At 130 °C, approximately 70 % of hydrogen was rapidly released from the 0.08 RbF‐doped sample within 180 min, and the fully dehydrogenated sample could absorb approximately 4.8 wt % of hydrogen at 120 °C. Structural analyses revealed that RbF reacted readily with LiH to convert to RbH and LiF owing to the favorable thermodynamics during ball‐milling. The newly generated RbH participated in the following dehydrogenation reaction, consequently resulting in a decrease in the reaction enthalpy change and activation energy.     

Enhanced photocatalytic activity of hybrid reduced graphene oxide–CeO2 hierarchical flower-like nanostructures

Research on Chemical Intermediates - The combination of the unique properties of graphene with functional characteristics of metal oxides is an interesting pathway to achieve desirable properties...     

L波段高功率波导缝隙阵设计与数值模拟

设计了一种基于宽边纵缝驻波阵的高功率射频微波辐射系统,系统由四路矩形波导以及聚四氟乙烯天线窗组成。天线内采用真空绝缘实现天线高功率容量,天线窗真空侧采用周期刻三角槽技术抑制高功率微波介质表面击穿。在波导缝隙阵与天线窗之间设计支撑板,除支撑天线窗外还可抑制表面波电流。采用HFSS数值模拟软件对辐射系统进行了优化设计。数值模拟结果表明,设计的辐射系统在频率为1.575 GHz时,增益为22.7 dBi,天线口径效率为98.3%,反射系数为-25 dB,带宽达到5%,带宽内天线增益波动小于等于0.4 dB、天线口径效率大于等于98%、主瓣指向偏差小于等于1.2。系统功率容量达到1.92 GW。     

水系锌离子电池钒基氧化物正极材料研究进展

近年来,钒基氧化物因为种类众多、理论比容量高和倍率性能优异等优点,被认为是一类具有潜在应用价值的水系锌离子电池正极材料。本文综述了V2O5、VO2等钒基氧化物材料的结构特点及其作为水系锌离子电池正极材料的最近研究进展。重点概述了当前钒基氧化物在锌离子电池中所面临的关键问题以及应对策略;最后,对钒基氧化物储锌材料的发展方向进行了展望。     

Tailoring Thermodynamics and Kinetics for Hydrogen Storage in Complex Hydrides towards Applications

Solid‐state hydrogen storage using various materials is expected to provide the ultimate solution for safe and efficient on‐board storage. Complex hydrides have attracted increasing attention over the past two decades due to their high gravimetric and volumetric hydrogen densities. In this account, we review studies from our lab on tailoring the thermodynamics and kinetics for hydrogen storage in complex hydrides, including metal alanates, borohydrides and amides. By changing the material composition and structure, developing feasible preparation methods, doping high‐performance catalysts, optimizing multifunctional additives, creating nanostructures and understanding the interaction mechanisms with hydrogen, the operating temperatures for hydrogen storage in metal amides, alanates and borohydrides are remarkably reduced. This temperature reduction is associated with enhanced reaction kinetics and improved reversibility. The examples discussed in this review are expected to provide new inspiration for the development of complex hydrides with high hydrogen capacity and appropriate thermodynamics and kinetics for hydrogen storage.

     

微波效应实验最小样本量估计分析

 为规范微波效应实验最小样本量,采用区间估计的统计推断方法,开展了样本作用概率与总体作用概率对应关系的分析和研究工作,对满足一定置信度和一定总体作用概率下所需要的最小样本量进行估计。研究结果表明,实验最小样本量确定为10是较为合理的。在80％的置信度下,当10支样本量样本作用概率达到70％时,总体作用概率置信下限约为51.6％。通过该方法能够将所获取的微波效应数据通过同一指标“总体作用概率置信下限”进行有效整理。     

A novel catalyst precursor K2TiF6 with remarkable synergetic effects of K, Ti and F together on reversible hydrogen storage of NaAlH4

A synergetic effect of K, Ti and F together on improving the reversible hydrogen storage properties of NaAlH(4) is found by intruding K(2)TiF(6) as catalyst precursor. Around 4.4 wt% of hydrogen can be released from the NaAlH(4)-0.025 K(2)TiF(6) sample within 40 min at 140 °C.