Oxygen permeation and phase structure properties of partially A-site substituted BaCo_(0.7)Fe_(0.225)Ta_(0.075)O_(3-δ) perovskites

Ba0.9R0.1Co0.7Fe0.225Ta0.075O3-δ(BRCFT, R = Ca, La or Sr) membranes were synthesized by a solid-state reaction. Metal cation Ca2+,La3+or Sr2+doping on A-site partially substituted Ba2+in BaCo0.7Fe0.225Ta0.075O3-δoxides, and its subsequent effects on phase structure stability, oxygen permeability and oxygen desorption were systematically investigated by XRD, TG-DSC, H2-TPR, O2-TPD techniques and oxygen permeation experiments. The partial substitution with Ca2+, La3+or Sr2+, whose ionic radii are smaller than that of Ba2+, succeeded in stabilizing the cubic perovskite structure without formation of impurity phases, as revealed by XRD analysis. Oxygen-involving experiments showed that BRCFT with A-site fully occupied by Ba2+exhibited good oxygen permeation flux under He flow, reaching about 2.3mL min-1 cm-2at 900 ℃ with 1 mm thickness. Of all the membranes, BLCFT membrane showed better chemical stability in CO2, owing to the reduction in alkalinity of the mixed conductor oxide by La doping. In addition, we also found the stability of the perovskite structure under reducing atmospheres was strengthened by increasing the size of A-site cation(Ba2+La3+Sr2+Ca2+).     

多糖凝胶的孔径和化学结构对单壁碳纳米管流动性和选择性分离的影响

基于凝胶柱色谱分离技术研究了单分散的单壁碳纳米管(SWCNTs)在不同化学结构多孔多糖凝胶中的流动特性以及对金属型(m-)/半导体型(s-)SWCNTs分离的影响.通过比较SWCNTs在一系列不同孔径的葡聚糖Sephacryl凝胶中的流动行为,发现减小孔径尺寸能够增强s-SWCNTs与凝胶之间的吸附作用力,使大直径的m-SWCNTs快速地流过凝胶颗粒,而选择性地保留了小直径的s-SWCNTs.进一步发现多糖凝胶化学结构比孔径尺寸在SWCNTs的m/s分离中起着更重要的作用.当基于葡聚糖结构的Sephacryl凝胶中的氨基结构被琼脂糖结构所取代时,如Superdex 200和Sepharose 2B凝胶会增强它们与SWCNTs之间的作用力,使SWCNTs的保留时间延长,降低了s-SWCNTs的选择性和纯度.此外,即使拥有与Sephacryl S100类似的孔径范围,当Sephacryl凝胶中的氨基被疏水环氧丙烷基团取代时,葡聚糖凝胶Sephadex G100与SWCNTs的作用力很弱,导致所有SWCNTs快速流动,无法实现SWCNTs的m/s分离.因而,我们认为凝胶孔径和化学结构共同影响并调控了SWCNTs的m/s分离的选择性、纯度以及分离效率.     

A Novel Coumarin-based Fluorescence Chemosensor for Fe^3＋

A novel coumarin derivative[7-diethylamino-2-oxo-2H-chromene-3-carboxylic acid（6-amino-pyridin2-yl）-amide,CFe1] has been synthesized and its potential application as a chemosensor for the detection of metal ions has been further investigated.The responses of CFe1 to Fe^3＋ were studied by fluorescence emission spectrometry in the presence of other metal ions such as Al^3＋,Ba^2＋,Ca^2＋,Co^3＋,Cr^3＋,Cu^2＋,Fe^2＋,Hg^2＋,Mg^2＋,Mn^2＋,Na^＋,Ni^＋,Pb^2＋,Zn^2＋,K^＋,and Ag^＋.CFe1 showed a good selectivity for Fe^3＋ with fast response,a wide pH span of 3.3-9.18,and a large Stocks shift.CFe1 in the presence of Fe^3＋ and ethylene diamine tetraacetic acid（EDTA） makes the blue solution fade to colorless,which is due to the formation of CFe1-Fe^3＋ complex instead of any catalytic action of Fe^3＋.Furthermore,the imaging of Fe^3＋ in cultured single mice microglia cells was realized with the aid of CFe1,indicating that CFe1 has a great potential to be used as promising models for the future design of novel and robust chemosensor for metal ion detection in the field of biomedical and environmental analyses.     

基于分子催化剂光驱动水氧化器件的研究进展

光解水制氢是人们解决未来能源危机的一种重要构想,构建高效的光电化学池是实现这一构想的重要途径,而光驱动水氧化的顺利进行是实现这一过程的关键.本文总结了近年来基于分子催化剂及染料敏化的光驱动水氧化分子器件的研究和进展,介绍了这些分子器件的组装和性能研究等,并根据这些研究的优点和不足提出一些浅见.     

欢迎订阅《高等学校化学学报》

正《高等学校化学学报》是中华人民共和国教育部委托吉林大学和南开大学主办的化学学科综合性学术刊物,以研究论文、研究快报和综合评述等栏目集中报道我国高等院校和中国科学院各研究所在化学学科及其相关的交叉学科、新兴学科、边缘学科等领域所开展的基础研究、应用研究和重大开发研究所取得的最新成果。本刊由中华人民共和国教育部从全国重点高等院校和中国科学院聘请89位学术造诣精深的化学家组成学术阵容强大的编委会,由著名高分子     

前言

<正>化学热力学是物理化学的重要分支学科.化学热力学应用热力学原理研究物质体系中的化学现象和规律,依据体系的宏观可测性质和热力学函数关系判断体系的稳定性、变化的方向和变化的程度.相平衡、化学平衡、热平衡、分子构象的稳定性、分子间的聚集与解离平衡等许多重要问题都需要用化学热力学的原理和方法进行判断和解决.化学热力学的主要特点是具有坚实的理论基础,其原理具有高度的可靠性和普适性,因此对理论研究和实际应用都有重要指导意义.化学热力学的研究范畴决定了它与化学乃至化学学科以外的其     

Chemoselective hydrogenolysis of tetrahydrofurfuryl alcohol to 1,5-pentanediol over Ir-MoOx/Si02 catalyst

In this work, MoOx promoted Ir/SiO2 catalysts were prepared and used for the selective hydrogenolysis of tetrahydrofurfuryl alcohol （THFA） to 1,5-pentanediol in a continuous flow reactor. The effects of different noble metals （Ir, Pt, Pd, Ru, Rh）, supports and Ir contents were screened. Among the investigated catalysts, 4 wt%Ir-MoOx/SiO2 with a Mo/Ir atomic ratio of 0.13 exhibited the best catalytic performance. The synergy between Ix particles and the partially reduced isolated MoOx species attached on them is essential for the excellent catalytic performance of Ix-MoOx/SiO2. The catalyst exhibited a better hydrogenolysis efficiency of THFA with the selectivity of 1,5-pentanediol of 65%-74% at a conversion of THFA of 70%-75% when the initial THFA concentration is ranging from 20 wt% and 40 wt%. And higher system pressure was also in favor of the conversion of THFA. During a stability test, the conversion of THFA and 1,5-pentanediol yield over Ix-MoOz/SiO2 decreased with reaction time, which can be explained by the leaching of Mo species during the reaction.     

Alkali metal cation doping of metal-organic framework for enhancing carbon dioxide adsorption capacity

Metal-organic frameworks （MOFs） have attracted much attention as adsorbents for the separation of CO2 from flue gas or natural gas. Here, a typical metal-organic framework HKUST-I（also named Cu-BTC or MOF-199） was chemically reduced by doping it with alkali metals （Li, Na and K） and they were further used to investigate their CO2 adsorption capacities. The structural information, surface chemistry and thermal behavior of the prepared adsorbent samples were characterized by X-ray powder diffraction （XRD）, thermo-gravimetric analysis （TGA） and nitrogen adsorption-desorption isotherm analysis. The results showed that the CO2 storage capacity of HKUST-1 doped with moderate quantities of Li＋, Na＋ and K＋, individually, was greater than that of unmodified HKUST-1. The highest CO2 adsorption uptake of 8.64 mmol/g was obtained with 1K-HKUST-1, and it was ca. 11% increase in adsorption capacity at 298 K and 18 bar as compared with HKUST- 1. Moreover, adsorption tests showed that HKUST-1 and 1K-HKUST-1 displayed much higher adsorption capacities of CO2 than those of N2. Finally, the adsorption/desorption cycle experiment revealed that the adsorption performance of 1K-HKUST-1 was fairly stable, without obvious deterioration in the adsorption capacity of CO2 after 10 cycles.     

应用化学专业“高分子化学”课程多维互动教学模式的探索

从高分子化学课程的特点和教学现状出发,针对应用化学的专业特点和培养目标,从课堂内和课堂外2个层面入手,注重理论和实践的有机结合,进行高分子化学课程多维互动教学模式的探索。通过多维互动教学模式的开展不断激发学生学习的激情,培养学习兴趣;结合教学内容提供学生更多自主探索和思考的空间,提高学生主观能动性;从学生的需求和专业发展的角度,逐步提高学生专业素养和专业能力,切实提高课程的教学效果。     

纤维状TiO2／Bi2O3光催化剂的制备及其光催化性能

研究了SrCo0．7Fe0．2Mo0．103-δ（SCFM）材料的相组成、微观结构、热膨胀系数、氧渗透性能和化学稳定性,其结果和文献中的SrCo0．8Fe0.2O3-δ（SCF）做了对比．通过EDTA-citric混合方法成功获得了纯相SCFM材料．SCFM材料在500-1050℃显示出比SCF材料更低的热膨胀系数（24×10^-6-29×10^-6／K）,表明其具有一种更稳定的结构,尽管由于Mo掺杂造成其透氧率比SCF材料低,但是SCFM的透氧率仍然维持在一个较高水平．证实SCF中的Mo掺杂能够阻止晶格中的有序-无序转变,提高了其在CO2下的化学稳定性．