Influence of the Oxide Content in the Catalytic Power of Raney Nickel in Hydrogen Generation

The influence of oxides in the hydrogen evolution on Raney nickel electrocatalysts was characterized by electrochemical impedance measurements. In addition, these materials show competitive overpotentials for hydrogen evolution with a modified Watts bath as a binder for the Raney nickel. The optimum result was ?190?mV of overpotential at 100?mA?cm^?2. Oxygen in the Raney Ni catalyst affects its electroactivity toward hydrogen evolution. The source of oxygen is related to the presence of chloride ions in the modified Watts bath. A Watts bath binds Raney Ni particles to the surface of the catalysts and chloride regulates the oxygen content in the nickel binder during electrodeposition. High oxygen content increases the hydrogen evolution overpotential of the electrode. The electroactivity of the synthesized porous coatings was evaluated by polarization curves and impedance plots. In addition, surface characterization by X-ray diffraction, field emission–scanning electron microscopy equipped with energy-dispersive analysis, and X-ray photoelectron spectroscopy is reported.     

X-Ray Analysis of Multi-Films for Electrochromic Device Application

Multilayer films based on tungsten oxide (WO₃), ITO (indium tin oxide) and CdS were deposited mainly by reactive dc magnetron sputtering onto glass substrates for electrochromic application. The thin films were analyzed by means of XPS (X-ray photoelectron spectroscopy), GIXD (grazing incidence X-ray diffraction) and XRD (X-ray diffraction). XRD and XPS results confirmed that the films were WO₃, CdS and ITO, respectively. The surface and interface of the CdS/ITO bi-layered film was studied by GIXD in different incidence angles. Detailed results about the amorphous characterization of the films during room temperature growth and post annealing are given.     

Precipitation of nanostructured copper oxalate: substructure and growth mechanism

The possibility of controlling materials properties by tailoring their substructure at the nanometer scale is a current topic of great interest. To do so, a fundamental understanding of the growth mechanism is of key importance and an analytical challenge as nanostructured materials are often produced by precipitation methods at high supersaturations where formation kinetics are fast. The current study focuses on the precipitation of copper oxalate, which has been previously shown to produce self-assembled ordered nanostructured particles with the promise of being able to tailor this nanometer substructure. In the current study we investigate in detail the growth mechanism and kinetics of precipitation by using in-situ particle size measurement or by stopping the reaction at various stages and using ex-situ methods. Combining the ex-situ methods of high-resolution scanning electron microscopy, transmission electron microscopy, and X-ray powder diffraction along with the in-situ methods, we were able to follow the growth process from 2 min to 2 weeks. The results in the 2-30 min period lead to the proposal of a core-shell growth model with a poorly ordered core and a well-structured shell of nanosized crystallites (50-70 nm), adding support to the brick-by-brick model previously proposed for this phase of particle growth. Particle evolution over long periods up to 2 weeks show a ripening which produces lens-shaped particles that eliminate the "high" surface energy faces observed in the earlier stages of growth. A more complete growth mechanism for copper oxalate precipitation at moderate supersaturations is proposed similar to recent findings for other self-assembled nanostructured particles.     

基于软X射线光谱的锂电池材料的电子结构与演变的研究进展

开发新型高能量密度以及低成本的锂离子电池, 是有效应对能源危机和环境挑战的可行路径之一. 锂离子电池材料的电子结构与电子态的演化决定了材料诸多本征性质以及电池综合性能. 探测并操控电极材料电子态的演化对探求电极反应的物理机理、 促进电池材料发展具有重要意义. 基于同步辐射的软X射线光谱技术可以直接探测费米能级附近的电子态. 本文从阴阳离子氧化还原反应的不同角度对利用软X射线光谱对电子态演变的研究进行了总结, 获得了电极材料电化学循环过程中过渡金属与氧的电子态演化信息, 系统阐述并总结了不同锂离子电池材料中电子态的演化以及氧化还原反应机理的最新研究进展.     

锂电池原位与非原位表征技术研究

锂电池的电化学性能与电子及离子在体相与界面的输运、反应、储存行为有关. 从原子尺度到宏观尺度,对电池材料在平衡态与非平衡态过程的电子结构、晶体结构、微观形貌、化学组成、物理性质的演化研究对于理解锂离子电池中各类构效关系至关重要,这需要综合多种原位与非原位表征技术. 目前,基础研究处于前沿的发达国家在这些方面取得了卓有成效的进展. 本文简介了中国科学院物理研究所近年来通过国内外合作,采用原位X射线衍射（in-situ XRD）、原位X射线吸收谱（in-situ XAS）、准原位/原位扫描电镜（quasi/in-situ SEM）、球差校正扫描透射电镜（HAADF/ABF-STEM）、扫描力曲线（Force-Curve）、中子衍射（Neutron Diffraction）、热重-差示扫描量热-质谱联用（TG-DSC-MS）、表面增强拉曼（SERS）等技术研究锂离子电池电极材料结构演化方面的进展,并对未来锂离子电池研究中先进表征技术的发展进行了简要的探讨.     

Preparation and Optical Properties of (Nanometer MCM-41)-CdS Composite Materials

The nanometer and micrometer molecular sieves MCM-41 were prepared by a hydrothermal method. Cadmium (II) was exchanged into the molecular sieves by ion-exchange, and thioacetamide was then used as a precursor of hydrogen sulfide for sulphidizing the (MCM-41)-cadmium samples to prepare the host-guest composite materials (MCM-41)-CdS. By means of chemical analysis, powder X-ray diffraction, infrared spectroscopy, low temperature nitrogen adsorption-desorption technique, solid state diffuse reflectance absorption spectroscopy and luminescence, the prepared materials were characterized. The chemical analysis shows that the guest is successfully trapped in the molecular sieves. The powder X-ray diffraction suggests that the frameworks of the molecular sieves in the prepared host-guest composite materials are retained during the preparative process. They are intact and the degrees of crystallinity are still very high. The infrared spectra show that the frameworks of the prepared host-guest materials keep intact. The low temperature nitrogen adsorption-desorption studies indicate that the pore volumes, the pore sizes and the surface areas of the prepared composite materials decrease relative to those of the MCM-41 molecular sieve hosts. This shows that the guests are successfully encapsulated in the channels of the molecular sieves. The solid state diffuse reflectance absorption spectra of the prepared host-guest composites show some blue-shifts relative to that of bulk cadmium sulfide, indicating that the guests are trapped in the channels of the molecular sieves. This shows the obvious stereoscopic confinement effect of the molecular sieve host on the nanometer cadmium sulfide guest. The (nanometer MCM-41)-CdS and (micrometer MCM-41)-CdS samples show obvious luminescence.     

Spectroscopic analysis of roman wall paintings from Casa del Mitreo in Emerita Augusta, Mérida, Spain

The use of visible spectroscopy, applied to chromatic characterization of Roman wall paintings, allows an easy and trustworthy grouping of the samples studied. The use of other spectroscopic techniques such as Fourier transform infrared spectroscopy (FTIR) and energy-dispersive X-ray spectroscopy (EDS) in conjunction with X-ray diffraction (XRD) allows a good identification of the substances present in the pictorial layers that define and differentiate each chromatic group. In this paper, a study of 40 Roman wall painting samples, from Pinturas Báquicas of Casa del Mitreo in Emerita Augusta (Mérida, Spain), is described. In these samples, some pigments of high quality and cost, as well as some unusual mixtures, not described in the bibliography, have been found.     

不同结构形态的纳米氢氧化钕的Nd3+增强电子拉曼光谱的研究

利用X射线粉末衍射、透射电子显微术、电子衍射和场发射电子扫描显微术，对不同方法制备的形态、颗粒大小不同的纳米Nd（OH）3进行钕离子的增强电子拉曼光谱研究，发现晶体结构、形态不同的纳米Nd（OH）3由于配位环境变化，导致钕离子的电子拉曼光谱在2600-1600cm^-1附近拉曼谱带的峰形、峰位和峰的数目产生显著变化。     

Structural characteristics of soluble fullerene films

Films of two fullerenes, functionalized with different solubilizing moieties, in the pure form and blended with poly(3-hexylthiophene), have been investigated by cyclic voltammetry, X-ray diffraction and UV-Vis spectroscopy techniques. The conclusion drawn from this characterization is that the supramolecular order of the films affects the physicochemical characteristics of these materials, and depends on the nature of the solubilizing substituents linked to the fullerene moiety. Implications for the use of such films in fullerene-based solar cells are also presented and discussed.     

金属-有机框架作为异相催化剂的表征方法概述

作为一类具有大的比表面积、高孔隙率、合成方便、骨架规模可变、化学可修饰以及结构组成多样等优点的新型多孔材料,金属-有机框架（MOFs）在光电材料、药物传输、气体吸附分离及催化等领域有着广阔的应用前景,成为近年来研究的热点。异相催化是MOFs最具发展潜力的应用领域之一,各种表征方法和研究手段是开展MOFs异相催化研究的工作基础。本文主要围绕表征MOFs作为异相催化剂的常用技术手段进行介绍,包括X-射线单晶衍射、X-射线粉末衍射、热重分析、红外光谱/拉曼光谱分析、透射/扫描电镜等,旨在为开展相关MOFs催化研究提供一定参考。     

Mg3(VO4)2的环己烷氧化脱氢性能与X射线光电子能谱分析

采用X射线光电子能谱对柠檬酸法制备的Mg3( VO4)2催化剂表面物种进行了研究,并结合X射线衍射(XRD)、扫描电镜(SEM)、傅立叶红外光谱(FT-IR)和氢气程序升温还原(H2 - TPR)对催化剂的表征结果及其在环己烷氧化脱氢反应中的催化性能,进一步探讨了Mg3( VO4)2催化剂表面物种与其催化性能之间的关系...     

Experimental Evidence for the Incorporation of Two Metals at Equivalent Lattice Positions in Mixed-Metal Metal–Organic Frameworks

Metal–organic frameworks containing multiple metals distributed over crystallographically equivalent framework positions (mixed-metal MOFs) represent an interesting class of materials, since the close vicinity of isolated metal centers often gives rise to synergistic effects. However, appropriate characterization techniques for detailed investigations of these mixed-metal metal–organic framework materials, particularly addressing the distribution of metals within the lattice, are rarely available. The synthesis of mixed-metal FeCuBTC materials in direct syntheses proved to be difficult and only a thorough characterization using various techniques, like powder X-ray diffraction, X-ray absorption spectroscopy and electron paramagnetic resonance spectroscopy, unambiguously evidenced the formation of a mixed-metal FeCuBTC material with HKUST-1 structure, which contained bimetallic Fe−Cu paddlewheels as well as monometallic Cu−Cu and Fe−Fe units under optimized synthesis conditions. The in-depth characterization showed that other synthetic procedures led to impurities, which contained the majority of the applied iron and were impossible or difficult to identify using solely standard characterization techniques. Therefore, this study shows the necessity to characterize mixed-metal MOFs extensively to unambiguously prove the incorporation of both metals at the desired positions. The controlled positioning of metal centers in mixed-metal metal–organic framework materials and the thorough characterization thereof is particularly important to derive structure–property or structure–activity correlations.     

Studies of carbon monoxide oxidation on carbon-supported platinum-osmium electrocatalysts

The electrocatalytic oxidation of hydrogen in the presence of carbon monoxide was studied on PtOs/C electrocatalysts prepared by the formic acid method and heat-treated under several temperatures and atmospheres. The physical properties of the metallic phase were evaluated by X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, and in situ X-ray absorption spectroscopy (XAS). The electrochemical performance of these materials was evaluated by single-cell polarization measurements, cyclic voltammetry, and linear sweep CO stripping voltammetry. The results have shown an enhancement of the CO oxidation process for the as-prepared PtOs/C and for a material heat-treated in a reducing atmosphere (hydrogen at 500 °C), compared to Pt/C. The electrochemical data also showed that the as-prepared and hydrogen-treated PtOs/C catalysts present CO tolerance higher than Pt/C. This has been associated with the occurrence of a surface reaction of CO adsorbed on Pt and oxygenated Os sites, favored by an intimate physical contact between segregated Os and Pt phases.Dedicated to Prof. Wolf Vielstich on the occasion of his 80th birthday in recognition of his numerous contributions to interfacial electrochemistry     

Ultrafine palladium particles immobilized on polymer microspheres

Ultrafine palladium particles immobilized on submicrometer copolymer microspheres were prepared by reduction of palladium ions in the presence of the copolymer microspheres. Copolymer microspheres with surface carboxylic or cyano functionality were used. Transmission electron microscopy observation and X-ray diffraction analysis indicated that ultrafine palladium particles of nanometer size were formed and were attached on the surface of the copolymer microspheres. The interaction between palladium particles and surface functionality of the copolymer microspheres was studied by IR spectroscopy and X-ray photoelectron spectroscopy. Received: 9 February 2000 Accepted: 17 August 2000     

Platinum alloying effects on the behavior of a metal hydride electrode

This is a study of the alloy structure, cycling life, and reaction kinetics of LaNi_4.7–x Sn_0.3Pt _x (x=0 and 0.1) metal hydride electrodes, using X-ray diffraction, X-ray absorption spectroscopy, electrochemical charge/discharge cycling, and electrochemical impedance spectroscopy. It is seen that the presence of platinum in the alloy causes an increase of the cycle life and a decrease in the hydrogen equilibrium pressure, activation time, charge storage capacity, and the rate of capacity decay during multicycling. XANES results are consistent with a decrease in the Ni oxidation in the Pt-containing alloy after the electrode cycling, indicating a protection introduced by Pt against Ni oxidation. It was also found that the catalytic activity of charge/discharge is improved with Pt alloying, a factor exclusively related to an increase of the active area due to higher alloy pulverization.     

Efficient hydrogen storage with the combination of lightweight Mg/MgH2 and nanostructures

Efficient hydrogen storage plays a key role in realizing the incoming hydrogen economy. However, it still remains a great challenge to develop hydrogen storage media with high capacity, favourable thermodynamics, fast kinetics, controllable reversibility, long cycle life, low cost and high safety. To achieve this goal, the combination of lightweight materials and nanostructures should offer great opportunities. In this article, we review recent advances in the field of chemical hydrogen storage that couples lightweight materials and nanostructures, focusing on Mg/MgH(2)-based systems. Selective theoretical and experimental studies on Mg/MgH(2) nanostructures are overviewed, with the emphasis on illustrating the influences of nanostructures on the hydrogenation/dehydrogenation mechanisms and hydrogen storage properties such as capacity, thermodynamics and kinetics. In particular, theoretical studies have shown that the thermodynamics of Mg/MgH(2) clusters below 2 nm change more prominently as particle size decreases.     

Variable temperature infrared spectroscopy: a convenient tool for studying the thermodynamics of weak solid-gas interactions

This tutorial review describes the use of variable temperature infrared spectroscopy of adsorbed species (VTIR), a recent method for studying the thermodynamics of weak solid-gas interactions. Examples show how a fundamental relationship of thermodynamics (the van't Hoff equation, used long since in several fields of physical chemistry) can describe equilibrium processes at the solid-gas interface. The VTIR method is fully exploited by measuring absorbance of an IR band, temperature and pressure over a wide temperature range: an estimation of the interaction energy is, however, possible even ignoring the equilibrium pressure. Precise thermodynamic characterization of solid-gas interactions is required in several fields: on the applied side, gas sensing, separation and storage, which involve such areas as work-place security, air pollution control and the energy sector; regarding fundamental knowledge, weak solid-gas interactions are relevant to a number of fields, including hydrogen bonding, coordination chemistry and surface phenomena in a broad sense.Infrared (IR) spectroscopy of (gas) molecules adsorbed on a solid is frequently used to characterize both, the adsorbed species and the adsorbing centres at the solid surface. The potential of the technique can be greatly enhanced by obtaining IR spectra over a temperature range, and simultaneously measuring IR absorbance, temperature and equilibrium pressure. When this is done, variable temperature infrared (VTIR) spectroscopy can be used not only for a more detailed surface characterization, but also for precise studies on the thermodynamics of solid-gas interactions. Furthermore, when weak interactions are concerned, the technique shows favourable features compared to adsorption calorimetry, or to other classical methods. The potential of the VTIR method is highlighted by reviewing recently reported studies on dihydrogen, dinitrogen and carbon monoxide adsorption on zeolites. To facilitate understanding, an outline of the basis of the method is also given, together with an appraisal of the critical points involved in its practical use.     

Hard X-ray micro-spectroscopy at Berliner Elektronenspeicherring für Synchrotronstrahlung II

The capabilities of the X-ray beamlines at Berliner Elektronenspeicherring für Synchrotronstrahlung II (BESSY II) for hard X-ray measurements with micro- and nanometer spatial resolution are reviewed. The micro-X-ray fluorescence analysis (micro-XRF), micro-extended X-ray absorption fine structure (micro-EXAFS), micro-X-ray absorption near-edge structure (micro-XANES) as well as X-ray standing wave technique (XSW), X-ray beam induced current (XBIC) in combination with micro-XRF and micro-diffraction as powerful methods for organic and inorganic sample characterization with synchrotron radiation are discussed. Mono and polycapillary optical systems were used for fine X-ray focusing down to 1 µm spot size with monochromatic and white synchrotron radiation. Polycapillary based confocal detection was applied for depth-resolved micro-XRF analysis with a volume resolution down to 3.4 · 10^− 6 mm³. Standing wave excitation in waveguides was also applied to nano-EXAFS measurements with depth resolution on the order of 1 nm. Several examples of the methods and its applications in material research, biological investigations and metal-semiconductor interfaces analysis are given.     

从分子碎片到活性位：分子筛催化材料的原位、共振紫外拉曼光谱研究

在过去的近十年中,各种新型原位表征技术和反应器设计被应用于多相催化过程和催化材料的合成研究中,并获得了许多新认识．特别是最近几年,利用原位、共振拉曼光谱技术对分子筛合成关键物种检测、杂原子分子筛催化活性位的研究取得了一系列进展．这些技术的应用使得从分子水平认识复杂的多孔材料成为可能：从合成初期碎片基元检测、碎片相互连接的关键化学键到预组装类微孔结构;从高度隔离过渡金属中心到配位化学键断裂生成活性中间物种,再到完成催化反应循环．这为设计特定功能和结构的催化材料及高选择性的活性中心奠定了坚实的基础．