Suchergebnisse

Die neuere Entwicklung der Medien ist gekennzeichnet durch Autonomiezuwachs, Ökonomisierung und Internationalisierung. Während auf diesen Ebenen die klassischen Regelungsmechanismen versagen müssen, lassen sie sich auf der Ebene der verbreiteten Inhalte einklagen. Aus einer funktional-strukturellen Perspektive wird die Idee der Selbstregulierung und legitimation des Systems Journalismus analysiert. Der Forschungsstand zum selbstreferentiellen Medienjournalismus wird wiedergegeben. Im Mittelpunkt steht eine empirische Untersuchung zur Einschätzung der Medienberichterstattung durch das Publikum. Darin wurden 113 Studierende der Publizistik- und Kommunikationswissenschaft der Universität Bochum 1997 und 1998 befragt. Insgesamt wird deutlich, dass reflexive Medienberichterstattung der starken Fremdregulierung den zunehmenden Glaubwürdigkeitsverlusten der Medien und des Journalismus entgegenwirken könnte. Diese Chance wird aber nicht genutzt. (BB)

Discerning the influence of electrochemical reactions on the electrode microenvironment is an unavoidable topic for electrochemical reactions that involve the production of OH- and the consumption of water.That is particularly true for the carbondioxide reduction reaction (CO2RR), which together with the competing hydrogen evolution reaction (HER) exert changes in the local OH- and H2O activity that in turn can possibly affect activity, stability, and selectivity of the CO2RR. We determine the local OH- and H2O activity in close proximity to a CO2-converting Ag-based gas diffusion electrode (GDE) with product analysis using gas chromatography. A Pt nanosensor is positioned in the vicinity of the working GDE using shear-force-based scanning electrochemical microscopy (SECM) approach curves, which allows monitoring changes invoked by reactions proceeding within an otherwise inaccessible porous GDE by potentiodynamic measurements at the Pt-tip nanosensor. We show that high turnover HER/CO2RR at a GDE lead to modulations of the alkalinity of the local electrolyte, that resemble a 16M KOH solution, variations that are in turn linked to the reaction selectivity. ; The authors are grateful to the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the framework of the Forschungsgruppe (FOR 2397-2) [276655287] and under Germany's Excellence Strategy—EXC 2033–390677874— RESOLV. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat[833408]). S.D. gratefully acknowledges financial sup- port by the International Max-Planck Research School on Reactive Structure Analysis for Chemical Reactions (IMPRS-RE- CHARGE). The authors declare no conflict of interest. Open access funding enabled and organized by Projekt DEAL

Co3O4 nanocubes are evaluated concerning their intrinsic electrocatalytic activity towards the oxygen evolution reaction (OER) by means of single-entity electrochemistry. Scanning electrochemical cell microscopy (SECCM) provides data on the electrocatalytic OER activity from several individual measurement areas covering one Co3O4 nanocube of a comparatively high number of individual particles with sufficient statistical reproducibility. Single-particle-on-nano-electrode measurements of Co3O4 nanocubes provide an accelerated stress test at highly alkaline conditions with current densities of up to 5.5 Acm-2, and allows to derive TOF values of up to 2.8 X104 s-1 at 1.92 V vs. RHE for surface Co atoms of a single cubic nanoparticle. Obtaining such high current densities combined with identical-location transmission electron microscopy allows monitoring the formation of an oxy(hydroxide) surface layer during electrocatalysis. Combining two independent single-entity electrochemistry techniques provides the basis for elucidating structure–activity relations of single electrocatalyst nanoparticles with well-defined surface structure. ; This research obtained funding from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the collaborative research centre/transregio 247 "Heterogeneous Oxidation Catalysis in the Liquid Phase" TRR 247 [388390466] (projects A2 and C3) as well as under Germany's Excellence Strategy-EXC 2033-390677874-RESOLV. This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]). The mechanical workshop team at the faculty of chemistry and biochemistry, Ruhr University Bochum, is acknowledged for the contribution in designing and building the nanoelectrode TEM holder. We acknowledge Prof. Patrick Unwin from the University of Warwick for providing the initial control software (WEC-SPM) for our SECCM experiments. Open Access funding enabled and organized by ...

Eine SEM‐gesteuerte Mikromanipulatortechnik wird vorgeschlagen, um einzelne Co3O4‐Nanopartikel aufzunehmen und auf der modifizierten Oberfläche einer Kohlenstoff‐Nanoelektrode zu platzieren. Damit kann die intrinsische Sauerstoffentwicklungsaktivität des Nanopartikels bei industriell relevanter Stromdichte ohne Film‐ und Ensemble‐Effekte bestimmt werden. Post‐elektrochemische TEM‐Analysen geben Einblick in die Strukturtransformationen während der Elektrokatalyse. ; Die Arbeiten wurden von der DFG im Rahmen des SFB/Transregio 247 "Heterogene Oxidationskatalyse in der Flüssigphase" TRR 247 [388390466] sowie im Rahmen der Deutschen Exzellenzstrategie – EXC 2033‐390677874 – RESOLV gefördert. Weiterhin wurden die Arbeiten vom ERC im Rahmen des European Union's Horizon 2020 Forschungs‐ und Innovationsprograms (CasCat [833408]) unterstützt. H.B.A. bedankt sich bei der Alexander von Humboldt‐Stiftung für ein Postdoc‐Stipendium. P.W. bedankt sich beim Fonds der chemischen Industrie e.V. (VCI) für die Unterstützung durch ein Doktorandenstiopendium. Open Access Veröffentlichung ermöglicht und organisiert durch Projekt DEAL.

Nano‐electrochemical tools to assess individual catalyst entities are critical to comprehend single‐entity measurements. The intrinsic electrocatalytic activity of an individual well‐defined Co3O4 nanoparticle supported on a carbon‐based nanoelectrode is determined by employing an efficient SEM‐controlled robotic technique for picking and placing a single catalyst particle onto a modified carbon nanoelectrode surface. The stable nanoassembly is microscopically investigated and subsequently electrochemically characterized. The hexagonal‐shaped Co3O4 nanoparticles demonstrate size‐dependent electrochemical activity and exhibit very high catalytic activity with a current density of up to 11.5 A cm−2 at 1.92 V (vs. RHE), and a turnover frequency of 532±100 s−1 at 1.92 V (vs. RHE) towards catalyzing the oxygen evolution reaction. ; This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the collaborative research centre/transregio 247 "Heterogeneous Oxidation Catalysis in the Liquid Phase" TRR 247 [388390466] as well as under Germany's Excellence Strategy—EXC 2033‐390677874—RESOLV. The project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement CasCat [833408]). H.B.A. acknowledges the Alexander von Humboldt foundation for a Postdoc fellowship. P.W. is grateful to the Association of the Chemical Industry e.V. (VCI) for funding of the PhD fellowship. Open access funding enabled and organized by Projekt DEAL.

Large scale CO2 electrolysis can be achieved using gas diffusion electrodes (GDEs), and is an essential step towards broader implementation of carbon capture and utilization strategies. Different variables are known to affect the performance of GDEs. Especially regarding the catalyst loading, there are diverging trends reported in terms of activity and selectivity, e.g. for CO2 reduction to CO. We have used shear–force based Au nanoelectrode positioning and scanning electrochemical microscopy (SECM) in the surface- generation tip collection mode to evaluate the activity of Au GDEs for CO2 reduction as a function of catalyst loading and CO2 back pressure. Using a Au nanoelectrode, we have locally measured the amount of CO produced along a catalyst loading gradient under operando conditions. We observed that an optimum local loading of catalyst is necessary to achieve high activities. However, this optimum is directly dependent on the CO2 back pressure. Our work does not only present a tool to evaluate the activity of GDEs locally, it also allows drawing a more precise picture regarding the effect of catalyst loading and CO2 back pressure on their performance. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]) as well as from the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) in the framework of the research unit FOR 2397e2 (276655237). M. C. O. M. and M. T. M. K. acknowledge the support of the European Commission under contract 722614 (Innovative Training Network Elcorel).

Das Förderprogramm zur Förderung von Umwelt- und Naturschutzprojekten, die von Vereinen und Verbänden durchgeführt werden (kurz "Verbändeförderung"), hat die "Stärkung des öffentlichen Bewusstseins und des Engagements für Umweltschutz und Naturschutz" zum Ziel. Durchgeführt wird das Programm gemeinsam durch das Umweltbundesamt (UBA), das Bundesamt für Naturschutz (BfN) und das Bundesumweltministerium (BMUV). Die vorliegende Evaluation untersucht die Verbändeförderung im Zeitraum 2008 bis 2019 und fokussiert auf folgende Evaluationsaspekte: Passfähigkeit des Programms, Zielerreichung (Output), Wirkungen auf die Programmbeteiligten (Outcomes) sowie Verstetigung und Breitenwirkung (Impacts). Die Evaluation basiert auf einem Methodenmix bestehend aus quantitativen und qualitativen Vorgehensweisen sowie reaktiven und non-reaktiven Verfahren. Die Evaluationsergebnisse zeigen, dass das Programm der Verbändeförderung auch heute noch relevant ist und aktuelle Bedürfnisse bedient. Das Design des Programms, insbesondere die monetäre Ausgestaltung und Laufzeit sowie die Zusammensetzung der geförderten Projekte, sind in ihrer grundsätzlichen Ausgestaltung zum Großteil passend, um die Ziele des Programms zu realisieren. Auch die Nutzung von Multiplikatoren in den Projekten ist gut gelungen und trägt zur Zielerreichung bei. Insbesondere Effekte auf Einstellungs- und Verhaltensänderung hinsichtlich Umwelt- und Naturschutzbelangen konnte die Evaluation nur qualitativ begutachten. Allerdings fehlt dem Programm bislang ein Programmmonitoring auf Basis dessen die Effekte des Programms abgebildet werden können. Zudem sehen die Evaluator:innen Verbesserungsbedarf bei der Außendarstellung der Verbändeförderung und einzelner Projekte. Zusammenfassend lässt sich festhalten, dass die Stärken des Förderansatzes überwiegen und die Aussicht besteht, mit einigen weiteren Anpassungen die Wirksamkeit der Förderung in Zukunft noch weiter zu erhöhen.

The number of active sites and their intrinsic activity are key factors in designing high-performance catalysts for the oxygen evolution reaction (OER). The synthesis, properties, and in-depth characterization of a homogeneous CoNiFeCu catalyst are reported, demonstrating that multimetal synergistic effects improve the OER kinetics and the intrinsic activity. In situ carbon corrosion and Cu leaching during the OER lead to an enhanced electrochemically active surface area, providing favorable conditions for improved electronic interaction between the constituent metals. After activation, the catalyst exhibits excellent activity with a low overpotential of 291.5 ± 0.5 mV at 10 mA cm−2 and a Tafel slope of 43.9 mV dec−1. It shows superior stability compared to RuO2 in 1 m KOH, which is even preserved for 120 h at 500 mA cm−2 in 7 m KOH at 50 °C. Single particles of this CoNiFeCu after their placement on nanoelectrodes combined with identical location transmission electron microscopy before and after applying cyclic voltammetry are investigated. The improved catalytic performance is due to surface carbon corrosion and Cu leaching. The proposed catalyst design strategy combined with the unique single-nanoparticle technique contributes to the development and characterization of high-performance catalysts for electrochemical energy conversion. ; This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the collaborative research center/transregio 247 "Heterogeneous Oxidation Catalysis in the Liquid Phase" TRR 247 [388390466] as well as under Germanys Excellence Strategy—EXC 2033-390677874—RESOLV. The project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (Grant Agreement CasCat [833408]). J.Z. acknowledges the Chinese Scholarship Council for a Ph.D. fellowship. This work was supported by the "Center for Solvation Science ZEMOS" funded by the German Federal Ministry of Education and ...

Rational design of highly active electrocatalysts for the oxygen evolution reaction (OER) is critical to improving overall electrochemical water splitting efficiency. This study suggests hollow CeO2@Co2N nanosheets synthesized using Co-ZIF-L as a precursor, followed by a hydrothermal reaction and a nitridation process as very attractive OER catalysts. The increased activity is supposed to be due to nitridation and strong electronic interaction between CeO2 and Co2N that contribute to the formation of active CoOOH phase. The synthesized CeO2@Co2N exhibits low overpotentials of 219 and 345 mV at OER current densities of 10 and 100 mA cm–2, respectively, as well as a long-term durability of 30 h at a comparatively high current density of 100 mA cm−2. ; This research was funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the collaborative research center/ transregio 247 "Heterogeneous Oxidation Catalysis in the Liquid Phase" TRR 247 (388390466). The project received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement CasCat (833408)). J.Z. acknowledges the Chinese Scholarship Council for a Ph.D. fellowship. Open access funding enabled and organized by Projekt DEAL.

Scanning electrochemical cell microscopy (SECCM) is increasingly applied to determine the intrinsic catalytic activity of single electrocatalyst particle. This is especially feasible if the catalyst nanoparticles are large enough that they can be found and counted in post-SECCM scanning electron microscopy images. Evidently, this becomes impossible for very small nanoparticles and hence, a catalytic current measured in one landing zone of the SECCM droplet cannot be correlated to the exact number of catalyst particles. We show, that by introducing a ruler method employing a carbon nanoelectrode decorated with a countable number of the same catalyst particles from which the catalytic activity can be determined, the activity determined using SECCM from many spots can be converted in the intrinsic catalytic activity of a certain number of catalyst nanoparticles. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement CasCat [833408]) as well as from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie MSCA-ITN Single-Entity Nanoelectrochemistry, Sentinel [812398]. S. S. and C. A. acknowledge the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) within the project [440951282]. X. X. C. acknowledges financial support from the Liaoning BaiQianWan Talents Program, China (No. 2019B042), and the Excellent Young Scientific and Technological Talents Project of Educational Department of Liaoning Province, China (No. 2020LNQN07). We acknowledge Prof. Patrick Unwin from the University of Warwick for providing the initial control software (WEC-SPM) for our SECCM experiments.

Developing highly efficient and selective electrocatalysts for the CO2 reduction reaction to produce value-added chemicals has been intensively pursued. We report a series of CuxOyCz nanostructured electrocatalysts derived from a Cu-based MOF as porous self-sacrificial template. Blending catalysts with polytetrafluoroethylene (PTFE) on gasdiffusion electrodes (GDEs) suppressed the competitive hydrogen evolution reaction. 25 to 50 wt % teflonized GDEs exhibited a Faradaic efficiency of & 54 % for C2+ products at -80 mAcm-2. The local OH- ions activity of PTFE-modified GDEs was assessed by means of closely positioning a Pt-nanoelectrode. A substantial increase in the OH-/H2O activity ratio due to the locally generated OH@ ions at increasing current densities was determined irrespective of the PTFE amount. ; This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (CasCat [833408]) as well as from the Deutsche Forschungsgemeinschaft (DFG) in the framework of the research unit FOR 2397e2 (276655237) and under GermanyQs Excellence Strategy-EXC 2033-390677874-RESOLV. C.A. acknowledges funding by the BMBF in the framework of the NanomatFutur project "MatGasDif" (03XP0263). N.S. acknowledges the Alexander von Humboldt foundation for a Postdoc fellowship. R. Wanka is acknowledged for contact angle measurements, Dr. Ulrich Hagemann from the Interdisciplinary Center for Analytics on the Nanoscale (ICAN), a core facility funded by the DFG (RI 00313) for a part of the XPS measurements and Dr. S. Cychy for adsorption measurements. Open Access funding enabled and organized by Projekt DEAL.

AbstractGas‐diffusion electrodes have been successfully employed in electrochemical chlorine production, and they also hold great potential in the field of electrochemical CO2 reduction. Herein, we demonstrate how sprayed Ag‐based gas‐diffusion electrodes, which show outstanding performance for the reduction of oxygen, need to be modified to produce CO from CO2. A computer‐controlled automated airbrush‐type spraying setup is used to systematically vary the core fabrication parameters of the process and investigate their effect on the electrochemical performance. Focused ion‐beam milling combined with scanning electron microscopy provides deeper insight into the structure of the electrodes and serves in combination with electrochemical data as the measure for the optimisation. Eventually, electrodes can be produced that suppress the evolution of H2 to the extent that an average Faradaic efficiency of 79% for CO can be maintained for at least 10 h at a current density of −100 mA∙cm−2.