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991.
992.
993.
Stabilization of Catalytically Active Cu+ Surface Sites on Titanium–Copper Mixed‐Oxide Films
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Dr. Ashleigh E. Baber Dr. Xiaofang Yang Dr. Hyun You Kim Dr. Kumudu Mudiyanselage Markus Soldemo Dr. Jonas Weissenrieder Dr. Sanjaya D. Senanayake Dr. Abdullah Al‐Mahboob Dr. Jerzy T. Sadowski Dr. Jaime Evans Dr. José A. Rodriguez Dr. Ping Liu Dr. Friedrich M. Hoffmann Dr. Jingguang G. Chen Dr. Darío J. Stacchiola 《Angewandte Chemie (International ed. in English)》2014,53(21):5336-5340
The oxidation of CO is the archetypal heterogeneous catalytic reaction and plays a central role in the advancement of fundamental studies, the control of automobile emissions, and industrial oxidation reactions. Copper‐based catalysts were the first catalysts that were reported to enable the oxidation of CO at room temperature, but a lack of stability at the elevated reaction temperatures that are used in automobile catalytic converters, in particular the loss of the most reactive Cu+ cations, leads to their deactivation. Using a combined experimental and theoretical approach, it is shown how the incorporation of titanium cations in a Cu2O film leads to the formation of a stable mixed‐metal oxide with a Cu+ terminated surface that is highly active for CO oxidation. 相似文献
994.
Back Cover: Surface Polarization Matters: Enhancing the Hydrogen‐Evolution Reaction by Shrinking Pt Shells in Pt–Pd–Graphene Stack Structures (Angew. Chem. Int. Ed. 45/2014)
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995.
996.
Polyimide‐silica (PI‐SiO2) hybrids were prepared from a novel polyimide (PI), derived from pyromellitic dianhydride (PMDA), 1,6‐bis(4‐aminophenoxy)hexane (synthesized) and 4,4′‐oxydianiline. SiO2 networks (5–30 wt%) were generated through sol–gel process using either tetraethylorthosilicate (TEOS) or a mixture of 3‐aminopropyltriethoxysilane‐PMDA‐based coupling oligomers (APA) and TEOS. Thin, free standing hybrid films were obtained from the respective mixtures by casting and curing processes. The hybrid films were characterized using Fourier transform infrared, 29Si nuclear magnetic resonance (NMR), field emission scanning electron microscopy (FE‐SEM), energy dispersive X‐ray spectrometry and atomic force microscopy (AFM) techniques. 29Si NMR results provide information about formation of organically modified silicate structures that were further substantiated by FE‐SEM and AFM micrographs. Contact angle measurements and thermogravimetric thermograms reveal that the addition of APA profoundly influences surface energy, interfacial tension, thermal stability and the residual char yield of modified hybrids in comparison to those obtained by mixing only TEOS. It was found that reduced particle size, efficient dispersion and improved interphase interactions were responsible for the eventual property enhancement. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
997.
Remziye Güzel Haslet Ekşi Zafer Üstündağ Ali Osman Solak 《Surface and interface analysis : SIA》2013,45(13):1821-1829
In this study, 4‐thiophenol modified glassy carbon electrode was prepared by the reduction of 4‐diazothiophenol tetrafluoroborate salt. Silver nanoparticles were attached to the thiophenol modified surface to prepare a thiophenol‐silver nanoparticle composite film. 4‐Aminothiopenol molecules were deposited by self‐assembling technique to form multi‐layered nanofilms of TP/SNP/PhNH2 on glassy carbon substrate. These surfaces were characterized by cyclic voltammetry, electrochemical impedance spectroscopy, X‐ray photoelectron spectroscopy, reflectance‐absorption infrared spectroscopy, and ellipsometry at each multilayer film growth process. Atomic force microscopic images of GC/TP/SNP/PhNH2 surfaces were also acquired. The characterization methods show that the amine group containing surface permits the subsequent modification by a variety of coupling reactions for the immobilization of more complex systems. An application of the electrode modification for the determination of uric acid with a significantly lower detection limit is described. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献
998.
Milindkumar S. Kalekar 《Journal of Dispersion Science and Technology》2013,34(7):1027-1034
Adsorption of various surfactants at the gas liquid interface is studied with equilibrium and dynamic surface tension measurements. The Wilhelmey plate method and maximum bubble pressure method are used for this study. Dynamic surface tension of solutions of different surfactants, sodium lauryl sulfate (SLS), polyoxyethylene glycol 4‐tert‐octyl phenyl ether (Triton X 100), poly‐oxyethylene(20) cetyl ether (Brij 58), and tetraethylene glycol mono‐n‐dodecyl ether (Brij 30), is measured at different concentrations. Adsorption of different surfactants is compared on the basis of equilibrium and dynamic behavior. Effectiveness and efficiency of different surfactants is found from equilibrium surface tension measurement. A new parameter is defined to quantify the dynamic behavior of adsorption, which gives the concentration of surfactant needed to reduce surface tension to half of its maximum reduction within a defined time available for adsorption. The dynamics of surfactant solution is quantified by using this parameter. 相似文献
999.
针对CO2热催化转化制甲醇过程中CO2吸附、活化较困难及副产物较多的问题,提出采用单原子Ge助剂修饰Cu(111)晶面的解决思路,通过密度泛函理论(DFT)计算研究了CO2在Ge-Cu(111)晶面上加氢合成甲醇的反应机理。结果表明,单原子Ge助剂的电子调控增加了与其相邻的 Cu 原子的电子云密度,使 CO2分子在含 Ge 活性界面上的吸附能力显著增强:CO2在 Ge-Cu(111)晶面上的吸附能约为Cu(111)晶面的1.5倍,约为Pd改性Cu(111)晶面的2.4倍,进而使逆水煤气变换(RWGS)反应路径速控步骤的活化能降低了近 20 kJ·mol-1,同时衍生出 3条生成甲醇的 RWGS新路径;此外,Ge-Cu(111)晶面上甲酸盐路径由于速控步骤活化能大幅上升而被禁阻,进而CO及烃类等副产物选择性大幅降低,Ge-Cu(111)晶面上CO2加氢制甲醇选择性升高。 相似文献
1000.
通过简单浸泡的方法在铜基底上制备出了具有微纳米复合结构的氧化铜,再利用混合硫醇溶液[含HS(CH2)9CH3和 HS(CH2)11OH]对浸泡后的表面进行修饰,通过控制溶液中HS(CH2)11OH的浓度,制备出一系列具有不同浸润性的铜表面,实现表面从超疏水到超亲水的有效调控. 研究发现,表面浸润的可控性源于表面复合结构与不同化学组成的协同作用,微纳米复合结构的存在为表面浸润性的调节提供了必要的条件. 相似文献