@misc{StaedterMuellerRachowetal., author = {St{\"a}dter, Matthias and M{\"u}ller, Klaus and Rachow, Fabian and Richter, Matthias and Schmeißer, Dieter}, title = {Ambient pressure thermal desorption spectroscopy (AP-TDS) of NiO/SiO2 catalysts}, series = {Environmental Earth Sciences}, volume = {70}, journal = {Environmental Earth Sciences}, number = {8}, issn = {1866-6280}, doi = {10.1007/s12665-013-2835-8}, pages = {3779 -- 3784}, abstract = {The Sabatier reaction is a key process in the "power-to-gas" application which is considered to con-tribute to future chemical energy storage systems. In this contribution we focus on the catalytic active sites of a NiO catalyst supported on SiO2(NiO/SiO2) which is commonly used in the Sabatier reaction. A novel technique for the characterization of the active sites is presented and dis-cussed using thermal desorption spectroscopy at ambient pressure. This analytical tool is operated under reaction conditions and allows element specific measurements during the catalytic process of CO2 reforming towards methane. Beside the desorption experiments, XPS and XAS measurements of pristine and catalytically used samples are performed to determine the influence of the Sabatier reaction conditions on the surface structure of the catalyst.}, language = {en} } @misc{MuellerRichterFriedrichetal., author = {M{\"u}ller, Klaus and Richter, Matthias and Friedrich, Daniel and Paloumpa, Ioanna and Kramm, Ulrike Ingrid and Schmeißer, Dieter}, title = {Spectroscopic characterization of Cobalt-Phthalocyanine electrocatalysts for fuel cell applications}, series = {Solid State Ionics}, journal = {Solid State Ionics}, number = {216}, issn = {1872-7689}, doi = {10.1016/j.ssi.2011.12.013}, pages = {78 -- 82}, abstract = {For polymer-electrolyte-membrane fuel cells (PEM-FC), platinumcatalysts on carbon based substrates are state of the art, due to high electrochemical activity and chemical stability in acid electrolytes. High costs of platinum force investigations of alternative catalysts. With respect to the oxygen reduction reaction, possible candidates are transition metal (TM) complexes like TM-porphyrines or TM-phthalocyanines. Pyrolysis on carbon based substrates improves the catalytic activity. Highest activities were found for Fe or Co as transition metal centers. We present results of the pyrolysis of Co-phthalocyanine (CoPc) on carbon black. Besides an investigation of morphology by scanning electron microscopy (SEM) and chemical composition by energy dispersive X-ray spectroscopy (EDX) and X-ray photoelectron spectroscopy (XPS) during pyrolysis, we present a near edge X-ray absorption fine structure (NEXAFS) study of the chemical composition for the related annealing steps. This investigation is accompanied by an electrochemical characterization of the catalytic activity and selectivity. The XPS and NEXAFS data indicate a decomposition of the CoN4(chelate-) complex during pyrolysis. The N1s data for 800 °C show graphite-like, formally pyrrolic and pyridinic like features, without any significant contri-bution of Co. The Co2p data for both, XPS and NEXAFS are dominated by CoO/Co2O3. It can be concluded that during the pyrolysis cobalt particles are formed by the disintegration of CoN4-centers, after pyrolysis these par-ticles become oxidized upon contact with air.}, language = {en} } @inproceedings{SchmeisserRichterTallarida, author = {Schmeißer, Dieter and Richter, Matthias and Tallarida, Massimo}, title = {Intrinsic defects in TiO2 to explain resistive switching devices}, series = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, booktitle = {Frontiers in Electronic Materials: A Collection of Extended Abstracts of the Nature Conference Frontiers in Electronic Materials, June 17 to 20 2012, Aachen, Germany}, editor = {Heber, J{\"o}rg and Schlom, Darrell and Tokura, Yoshinori and Waser, Rainer and Wuttig, Matthias}, publisher = {Wiley-VCH}, address = {Weinheim}, isbn = {978-3-527-41191-7}, doi = {10.1002/9783527667703.ch45}, pages = {255 -- 256}, language = {en} }