TY - JOUR A1 - Ortel, Erik A1 - Bernicke, M. A1 - Eckhardt, B. A1 - Bernsmeier, D. A1 - Schmack, R. A1 - Kraehnert, R. A1 - Lippitz, Andreas T1 - Synthesis and OER activity of NiO coatings with N2 - Catalysts based on nickel oxide are some of the most active catalysts for the oxygen evolution reaction (OER) in alkaline media. However, preparing catalytic coatings with high surface area and good accessibility of the active sites remains challenging. We present a new approach for the synthesis of homogeneous and binder-free nickel oxide coatings comprising a highly accessible ordered mesopore structure. The synthesis is achieved via evaporation induced self assembly utilizing PEOPB-PEO triblock copolymers as pore template and a chemical complex of Ni2+ and citric acid as precursor. Excessive crystallization behaviour of NiO is avoided by thermal conversion of the precursor into an amorphous Ni carbonate intermediate, followed by transition of the carbonate into the metal oxide. We present a comprehensive analysis of the obtained materials in terms of morphology, crystallinity, surface area, composition, and OER activity of differently calcined catalysts. Retaining a low crystallinity and high surface area during the Synthesis proofs to be the most important factor in obtaining a highly active OER catalyst. KW - XPS KW - nanoparticle KW - catalysis PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/slct.201600110/abstract DO - https://doi.org/10.1002/slct.201600110 VL - 2016 IS - 3/2016 SP - 482 EP - 489 PB - Wiley Online Library CY - Weinheim AN - OPUS4-35725 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Dietrich, Paul A1 - Glamsch, Stephan A1 - Ehlert, Christopher A1 - Lippitz, Andreas A1 - Kulak, N. A1 - Unger, Wolfgang T1 - Synchrotron-radiation XPS analysis of ultra-thin silane films: Specifying the organic silicon N2 - The analysis of chemical and elemental in-depth variations in ultra-thin organic layers with thicknesses below 5 nm is very challenging. Energy- and angle-resolved XPS (ER/AR-XPS) opens up the possibility for non-destructive chemical ultra-shallow depth profiling of the outermost surface layer of ultra-thin organic films due to its exceptional surface sensitivity. For common organic materials a reliable chemical in-depth analysis with a lower limit of the XPS information depth z95 of about 1 nm can be performed. As a proof-of-principle example with relevance for industrial applications the ER/AR-XPS analysis of different organic monolayers made of amino- or benzamidosilane molecules on silicon oxide surfaces is presented. It is demonstrated how to use the Si 2p core-level region to non-destructively depth-profile the organic (silane monolayer) – inorganic (SiO2/Si) interface and how to quantify Si species, ranging from elemental silicon over native silicon oxide to the silane itself. The main advantage of the applied ER/AR-XPS method is the improved specification of organic from inorganic silicon components in Si 2p core-level spectra with exceptional low uncertainties compared to conventional laboratory XPS. KW - Synchrotron radiation XPS KW - Depth profiling KW - Silanes KW - Monolayer KW - Amines KW - Amides PY - 2016 DO - https://doi.org/10.1016/j.apsusc.2015.12.052 SN - 0169-4332 SN - 1873-5584 VL - 363 SP - 406 EP - 411 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-35262 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Schwarz, F. A1 - Heinrich, Thomas A1 - Kaufmann, J. O. A1 - Lippitz, Andreas A1 - Puttreddy, R. A1 - Rissanen, K. A1 - Schalley, C. A. T1 - Photocontrolled on-surface pseudorotaxane formation with well-ordered macrocycle multilayers N2 - The photoinduced pseudorotaxane formation between a photoresponsive axle and a tetralactam macrocycle was investigated in solution and on glass surfaces with immobilized multilayers of macrocycles. In the course of this reaction, a novel photoswitchable binding station with azobenzene as the photoswitchable unit and diketopiperazine as the binding station was synthesized and studied by NMR and UV/Vis spectroscopy. Glass surfaces have been functionalized with pyridine-terminated SAMs and subsequently withmultilayers of macrocycles through layer-by-layer self assembly. A preferred orientation of the macrocycles could be confirmed by NEXAFS spectroscopy. The photocontrolled Deposition of the axle into the surface-bound macrocycle-multilayers was monitored by UV/Vis spectroscopy and led to an increase of the molecular order, as indicated by more substantial linear dichroism effects in angle-resolved NEXAFS spectra. KW - Well-ordered macrocycle multilayers KW - XPS KW - NEXAFS PY - 2016 DO - https://doi.org/10.1002/chem.201603156 SN - 0947-6539 SN - 1521-3765 VL - 22 IS - 40 SP - 14383 EP - 14389 PB - Wiley-VCH Verlag GmbH & Co. KGaA CY - Weinheim AN - OPUS4-38270 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Lange, Nele A1 - Dietrich, Paul M. A1 - Lippitz, Andreas A1 - Kulak, N. A1 - Unger, Wolfgang T1 - New azidation methods for the functionalization of silicon nitride and application in copper-catalyzed azide-alkyne cycloaddition (CuAAC) N2 - In this study, a new direct functionalization method of silicon nitride (Si3N4) using azidation and click chemistry is presented. First, amino groups (NHx) were created on a Si3N4 substrate by fluoride etching. These NHx-terminated Si3N4 surfaces were analyzed by chemical derivatization X-ray photoelectron spectroscopy (CD-XPS) with 4-trifluoromethylbenzaldehyde (TFBA) and a derivatization yield of 20% was concluded. In the second step freshly prepared NHx surfaces were transformed into azides which were used immediately in a click reaction with halogenated alkynes. The presented combination of amination, azidation and click reaction is a promising alternative for common silane-based Si3N4 functionalization methods. T2 - 16th European Conference on Applications of Surface and Interface Analysis CY - Granada, Spain DA - 28.09.2015 KW - XPS KW - Azidation KW - Click chemistry KW - Silicon nitride KW - Chemical derivatization PY - 2016 UR - http://onlinelibrary.wiley.com/doi/10.1002/sia.5950/full DO - https://doi.org/10.1002/sia.5950 VL - 48 SP - 621 EP - 625 PB - John Wiley & Sons, Ltd AN - OPUS4-36841 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Saravanan, S. A1 - Balamurugan, M. A1 - Lippitz, Andreas A1 - Fonda, E. A1 - Swaraj, Sufal T1 - XANES studies of titanium dioxide nanoparticles synthesized by using Peltophorum pterocarpum plant extract N2 - The preparation and characterization of a Titanium dioxide (TiO2) by a simple, cost effective, facile and eco-friendly green synthesis method using Peltophorum pterocarpum plant extract is presented. The green synthesized nanoparticles were characterized using X-ray diffraction (XRD), Raman spectroscopy, High-resolution transmission electron microscopy (HR-TEM) and X-ray absorption near edge spectroscopy (XANES). XRD results show that the prepared TiO2 NPs were significantly crystalline with various percentages of anatase and rutile phases. The nanoparticles were found to have different diameters ranging from 20 to 80 nm. No evidence of any intermediate or different TiO2 phases were found in XANES measurements performed at the Ti K- and L-edge. It is shown that the TiO2 NPs with high uniformity, high surface area and minimum aggregation can be prepared with relative ease and the desired anatase: rutile phase ratio can be obtained by controlling the experimental conditions. KW - XANES KW - Raman KW - XRD KW - NEXAFS KW - Titanium dioxide PY - 2016 UR - http://www.sciencedirect.com/science/article/pii/S0921452616304197 DO - https://doi.org/10.1016/j.physb.2016.09.011 SN - 0921-4526 IS - 503 SP - 86 EP - 92 PB - Elsevier B.V. CY - Amsterdam AN - OPUS4-39805 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Nietzold, Carolin A1 - Dietrich, Paul A1 - Lippitz, Andreas A1 - Panne, Ulrich A1 - Unger, Wolfgang T1 - Cyclodextrin – ferrocene host – guest complexes on silicon oxide surfaces N2 - Research on carbohydrate based interactions with proteins, nucleic acids or antibodies has gained increased interest in the last years especially in clinical diagnosis or drug development. The efficiency of diagnostic interfaces depends upon the number of probe molecules, e.g. carbohydrates. The control of surface parameters as density and distribution of immobilized carbohydrates is essential for a reliable interaction with protein analytes. A controlled production of biomolecular interfaces can be reached by a stepwise quality control during buildup of these biointerfaces. Here, ß-amino-cyclodextrin molecules were attached to amine-reactive silicon oxide surfaces via click chemistry to construct a model biosensor surface. The amount of surface bound carbohydrates was determined indirectly after chemical derivatization with 4-(trifluoromethyl)-benzylamine (TFMBA). Moreover, these surfaces were used to form host-guest complexes of ferrocene (guest) and β-cyclodextrin (host) moieties to mimic the target binding (sensing) of the model biosensor. Surface chemical analysis of all steps during biosensor construction was performed using X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure spectroscopy (NEXAFS). Our approach widens the possibilities to generate switchable surfaces based on ß-Cyclodextrin surfaces for biosensor applications. KW - ß-amino-cyclodextrin KW - Ferrocene KW - Guest complexe KW - XPS KW - NEXAFS PY - 2016 DO - https://doi.org/10.1002/sia.5958 SN - 0142-2421 SN - 1096-9918 VL - 48 IS - 7 SP - 606 EP - 610 PB - Wiley AN - OPUS4-36856 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Schwarz, F. A1 - Heinrich, Thomas A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Schalley, C. T1 - A photoswitchable rotaxane operating in monolayers on solid support N2 - A novel photoswitchable rotaxane was synthesised and its switching behaviour in solution was analysed with NMR and UV-Vis. A monolayer of rotaxanes was deposited on glass surfaces and the on-surface photoswitching was investigated. Angle-resolved NEXAFS spectra revealed a preferential orientation that reversibly changes upon switching. KW - XPS KW - NEXAFS KW - Photoswitchable rotaxane KW - Self assembly PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-386814 DO - https://doi.org/10.1039/c6cc08586e SN - 0022-4936 SN - 1364-548X SN - 0009-241x SN - 1359-7345 VL - 52 IS - 100 SP - 14458 EP - 14461 PB - Royal Society of Chemistry (RSC) AN - OPUS4-38681 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Ehlert, Christopher A1 - Holzweber, Markus A1 - Lippitz, Andreas A1 - Unger, Wolfgang A1 - Saalfrank, Peter T1 - A detailed assignment of NEXAFS resonances of imidazolium based ionic liquids N2 - In Near Edge X-Ray Absorption Fine Structure (NEXAFS) spectroscopy X-Ray photons are used to excite tightly bound core electrons to low-lying unoccupied orbitals of the system. This technique offers insight into the electronic structure of the system as well as useful structural information. In this work, we apply NEXAFS to two kinds of imidazolium based ionic liquids ([CnC₁im]⁺[NTf₂]⁻ and [C₄C₁im]⁺[I]⁻). A combination of measurements and quantum chemical calculations of C K and N K NEXAFS resonances is presented. The simulations, based on the transition potential density functional theory method (TP-DFT), reproduce all characteristic features observed by the experiment. Furthermore, a detailed assignment of resonance features to excitation centers (carbon or nitrogen atoms) leads to a consistent interpretation of the spectra. KW - Ionic liquids KW - NEXAFS KW - DFT spectrum simulations PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-367223 DO - https://doi.org/10.1039/c5cp07434g SN - 1463-9076 SN - 1463-9084 VL - 18 IS - 12 SP - 8654 EP - 8661 PB - Royal Society of Chemistry CY - Cambridge, UK AN - OPUS4-36722 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER - TY - JOUR A1 - Unger, Wolfgang A1 - Beiranvand, Z. A1 - Kakanejadifard, A. A1 - Donskyi, Ievgen A1 - Faghani, A. A1 - Tu, Z. A1 - Lippitz, Andreas A1 - Sasanpour, P. A1 - Maschietto, F. A1 - Paulus, B. A1 - Haag, R. A1 - Adeli, M. T1 - Functionalization of fullerene at room temperature: toward new carbon vectors with improved physicochemical properties N2 - In this work, fullerene has been functionalized with cyanuric Chloride at room temperature by a nitrene mediated [2 + 1] cycloaddition reaction. The adduct after functionalization is inherently in the form of azafulleroid and shows broad UV absorption in the wavelength range of 200–800 nm, as well as photothermal conversion and fluorescence with a high quantum yield. KW - Functionalization of fullerenes KW - XPS KW - NEXAFS PY - 2016 UR - https://nbn-resolving.org/urn:nbn:de:kobv:b43-387076 DO - https://doi.org/10.1039/c6ra23419d SN - 2046-2069 VL - 6 IS - 114 SP - 112771 EP - 112775 PB - Royal Society of Chemistry (RSC) AN - OPUS4-38707 LA - eng AD - Bundesanstalt fuer Materialforschung und -pruefung (BAM), Berlin, Germany ER -