Studies of protection of iron corrosion by rosin imidazoline self‐assembled monolayers

A type of rosin imidazoline (IM) has been synthesized using rosin acid and diethylenetriamine (DETA) as raw materials. The monolayers of IM were assembled on the surface of iron. The monolayers of the IM inhibitor were characterized by electrochemical impedance spectroscopy (EIS), electrochemical polarization curves and double‐layer capacitance. Surface analysis was carried out to establish the mechanism of corrosion inhibition of iron by X‐ray photoelectron spectroscopy (XPS) and scanning electron microscopy. The IM inhibitor showed good inhibition efficiency for iron in 0.1 M H₂SO₄. The inhibition mechanism of IM inhibitor was interpreted using molecular simulation. Copyright © 2006 John Wiley & Sons, Ltd.     

Nanoscale Chemical Imaging of the Reduction Behavior of a Single Catalyst Particle

A closer look : Investigation of the reduction properties of a single Fischer–Tropsch catalyst particle, using in situ scanning transmission X‐ray microscopy with spatial resolution of 35 nm, reveals a heterogeneous distribution of Fe⁰, Fe²⁺, and Fe³⁺ species. Regions of different reduction properties are defined and explained on the basis of local chemical interactions and catalyst morphology.

     

Uranium Oxide Nanocrystals by Microwave‐Assisted Thermal Decomposition: Electronic and Structural Properties

Uranium oxides have attracted much attention not only in the context of nuclear energy generation but also for their application as pristine catalysts or as supports for other (transition metal) oxides and (precious) metals. Their propensity to adopt high coordination numbers and manifest multiple oxidation states (from +II to +VI) makes them attractive candidates for catalyzed transformation reactions. Herein, we report a new synthesis route to phase‐pure, crystalline UO₂ nanoparticles via microwave‐assisted decomposition of a molecular uranium(IV) precursor. The electronic structure and optical absorption properties of these nanocrystals were investigated using spectroscopic methods to evaluate their suitability for photo(electro)catalytic applications.     

Polyaniline Nanofibrils Array Synthesized within the Anodic Aluminum Oxide Template

Introduction Many methods for the fabrication of nanoparticles have been developed ranging from lithographic techniques to chemical methods. The method termed template synthesis for preparation of a variety of micro- and nano-materials has been explored1-3. The template membranes employed contain cylindrical pores with mono-disperse diameters, that extend through the entire thickness of the membrane. The diameter of this nanocylinder is determined by the diameter of the pores of the template m…     

Interlaboratory study comparing analyses of simulated angle‐resolved X‐ray photoelectron spectroscopy data

An interlaboratory study has been conducted to determine the following: (i) the similarities and differences of film thicknesses and composition profiles obtained from analyses of simulated angle‐resolved X‐ray photoelectron spectroscopy (ARXPS) data by different analysts using different algorithms for data analysis, and (ii) the effects of two assumptions commonly made in data‐analysis algorithms for ARXPS on derived film thicknesses and composition profiles. The analyzed data were generated by the National Institute of Standards and Technology Database for the Simulation of Electron Spectra for Surface Analysis, (SESSA) which provides a simple way to study the influence of the aforementioned effects on compositional depth profile reconstruction. Sets of simulated ARXPS data were produced for thin films of SiO₂, SiON, HfO₂, and HfON of varying thicknesses on a Si substrate. For some HfON films, the N concentration varied with depth. Eleven groups participated in the round robin study. The majority (eight) employed a commercial ARXPS instrument in which the angular distribution is measured for a fixed sample geometry, in contrast to conventional ARXPS in which the sample is tilted for angular variation. The average deviations between the reported average depth, film thickness, and amount of material typically varied between 20% and 30% but were considerably larger, between 30% and 80%, for some cases. The average errors were generally larger for simulations that included elastic scattering and the finite analyzer‐acceptance angle (realistic conditions) than those for simulations that neglected elastic scattering and the finite analyzer‐acceptance angle (simplified conditions). The retrieved N depth profiles were quantitatively different from the true depth profiles and showed substantial variability among the group of members who used the same instrument and analysis software. Copyright © 2014 John Wiley & Sons, Ltd.     

Cover Picture: Nanoscale Chemical Imaging of the Reduction Behavior of a Single Catalyst Particle (Angew. Chem. Int. Ed. 20/2009)

Iron‐based catalysts for the Fischer–Tropsch synthesis bring about the conversion of synthesis gas (CO/H₂) derived from coal or biomass into liquid transportation fuels. In their Communication on page 3632 ff., B. M. Weckhuysen, F. M. F. de Groot, and co‐workers provide insights into the difference in behavior of the catalyst precursors during pretreatment in H₂ on both the nanoscopic and the bulk scale. These findings enable further understanding of how the activated catalyst works.

     

Formation of clay intercalates with organic bilayers in hydrocarbon polymers

The formation of clay intercalates with three different kinds of organic ammonium salts, when mixed in the presence of synthetic or natural polyisoprene rubber, has been investigated. X‐ray diffraction and transmission electron microscopy (TEM) experiments have shown that intercalates with organic bilayers, rather than with interdigitated organic monolayers, are obtained only for the ammonium salts presenting two long alkyl chains and only in the presence of the natural rubber (NR). These results have been qualitatively rationalized on the basis of suitable interlayer densities. Both monolayer and bilayer clay intercalates remain stable for short‐term heating procedures at temperatures lower than 250°C. For treatments at higher temperatures, where the decomposition of the organic ammonium salt occurs, both kinds of clay intercalates maintain intralayer crystalline order. However, the decomposition of the organic modifier leads to the formation of pristine and exfoliated clay for the intercalates with organic monolayers and bilayers, respectively. Copyright © 2008 John Wiley & Sons, Ltd.     

Energy band alignment of SnO2/SrTiO3 epitaxial heterojunction studied by X‐ray photoelectron spectroscopy

(200) SnO₂//(111) SrTiO₃ (STO) epitaxial heterojunctions were fabricated using the laser molecular epitaxy technique. Sharp junction interface was confirmed by the high‐resolution transmission electron microscopy. The valence band offset and conduction band offset of the SnO₂/STO heterojunction were determined to be 0.85 ± 0.20 and 0.45 ± 0.20 eV using XPS, respectively. It is found that a type‐II band alignment forms at the SnO₂/STO interface. Copyright © 2015 John Wiley & Sons, Ltd.     

The origin of the formation of cavities in galvanized coatings

The role of water‐soluble corrosion products on galvanized wires was examined. The samples used were industrial hot‐dip galvanized wires, which were exposed to the open air under all weather conditions for a relatively short time (6 and 12 months), in an urban environment close to the sea. The samples were studied by different methods, i.e. scanning electron microscopy (SEM), transmission electron microscopy (TEM), X‐ray diffraction (XRD) and optical microscopy (OM). Several phases were detected because of the galvanization procedure and the steel substrate. Furthermore, phases which were formed as a result of the reaction of zinc with the atmosphere were also detected. These were oxides like ZnO, carbonates like ZnCO₃ and hydrated Zn and Fe sulfates. Their presence influences the corrosion resistance of the wires, which finally, strongly depends on the solubility of the wires in water. The SO₄^2? compounds especially are very soluble and consequently are easily removed from the coating surface, leading to its degradation by the formation of cavities. In any case, their presence, even after a short period of exposure, implies that the coating is highly affected by the atmosphere of the modern city. Copyright © 2006 John Wiley & Sons, Ltd.     

New Insights into Sulfur Deposition on Gold Using Dithiobisphthalimide as a New Precursor

Dithiobisphthalimide is used as a new precursor for the spontaneous deposition of sulfur on gold surfaces in acetonitrile. Characterization of the modified surfaces is achieved using X‐ray photoelectron spectroscopy (XPS), electrochemistry and scanning tunneling microscopy (STM). The reported results indicate that the sulfur deposition is an efficient and fast process and that high coverages can be reached very quickly. Sequential high‐resolution STM in air allows the direct observation, for the first time, of the mobility of the usually observed rectangular structures as individual units. It also shows the reversible association/dissociation of these rectangles. The nature of these structures is highly debated in the literature and the present work provides new insights into their nature through the use of a new sulfur precursor under non‐traditional conditions. To explain our results we consider these structures as simple sulfur adlayers on the gold surface.     

Synthesis of scroll-type composite microtubes of Mo2C/MoCO by controlled pyrolysis of Mo(CO)6

Composite microtubes of Mo(2)C/MoCO have been synthesized for the first time under well-controlled conditions by thermal decomposition of Mo(CO)(6) at about 600 degrees C. Here, thermal stability and phase transition of the products, as well as the influence of reaction temperature and argon flow rate, have been carefully investigated. All samples were characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The reaction model and rolling mechanism were proposed on the basis of the experimental facts.     

Development of In Situ Electrochemical Scanning Electron Microscopy with Ionic Liquids as Electrolytes

We report that ionic liquids (ILs) can be observed by electron microscopy without any charging of the liquid. Based on this, we present an in situ electrochemical scanning electron microscopy (in situ ECSEM) system. The key technology that enables in situ ECSEM is that charges can be removed from an IL by grounding it with a Pt wire, even if the IL is in an insulating glass cell. As a first demonstration, we describe the redox reaction of a polypyrrole (PPy) film accompanied by changes in its thickness when it is polarized by the film‐deposited Pt electrode in the IL. Furthermore, energy‐dispersive X‐ray fluorescence (EDX) analysis can be employed for the electrode polarized in the IL. The component analysis by EDX of PPy in an IL containing K⁺ as a marker, reveals doping of electrolyte cations into the PPy film upon the latter′s reduction and dedoping of cations from the film upon oxidation.     

XPS与UPS测量几种材料功函数的比较

为比较X射线光电子能谱(XPS)与紫外光电子能谱(UPS)测量材料功函数结果间的差异,依次对经氩离子清洁表面吸附层的Au、Ag薄膜样品和单晶硅片,以及未进行表面清洁的Au、Ag、MoO_3薄膜样品,单晶硅片及ITO导电玻璃的功函数进行测量。给出了XPS和UPS测量功函数的计算方法,并探讨了影响材料功函数测量结果不确定性的因素。研究发现XPS及UPS在测量表面清洁的金属样品时,测量结果基本一致,具有较高的准确度,表面清洁的Au、Ag样品一经暴露空气后其表面覆盖一层吸附层,功函数很快发生变化。利用UPS或XPS测量金属和半导体的功函数时应避免暴露空气,若金属样品在空气中暴露时建议使用氩离子清洁表面。研究结果对科研人员按实际测试需求合理选择测量方法具有一定的指导意义。     

Asbestos mineral analysis by UV Raman and energy-dispersive X-ray spectroscopy.

The applicability of a UV micro-Raman setup was assessed for the rapid identification of fibrous asbestos minerals using 257 and 244 nm laser light for excitation. Raman spectra were obtained from six asbestos reference standards belonging to two basic structural groups: the serpentines (chrysotile) and the amphiboles (crocidolite, tremolite, amosite, anthophyllite, and actinolite). The UV Raman spectra reported here for the first time are free from fluorescence, which is especially helpful in assessing the hydroxyl-stretching vibrations. The spectra exhibit sharp bands characteristic of each asbestos species, which can be used for the unambiguous identification of known and unknown asbestos fibres. Evident changes of the relative band intensities sensitively reflect the chemical substitutions that typically occur in asbestos minerals. The elemental composition of the asbestos reference samples was analysed by using a scanning electron microscope equipped with an energy-dispersive X-ray (EDX) spectrometer. The discussion of the experimental results in terms of EDX analysis sheds new light on the structural and vibrational consequences of cation distribution in asbestos minerals.