Suchergebnisse

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.

We report heating rate measurements in a microfabricated gold-on-sapphire surface electrode ion trap with a trapping height of approximately 240 μm. Using the Doppler recooling method, we characterize the trap heating rates over an extended region of the trap. The noise spectral density of the trap falls in the range of noise spectra reported in ion traps at room temperature. We find that during the first months of operation, the heating rates increase by approximately one order of magnitude. The increase in heating rates is largest in the ion-loading region of the trap, providing a strong hint that surface contamination plays a major role for excessive heating rates. We discuss data found in the literature and the possible relation of anomalous heating to sources of noise and dissipation in other systems, namely impurity atoms adsorbed onto metal surfaces and amorphous dielectrics. ; Austria. Federal Ministry of Science and Research ; Austria. Federal Ministry of Science and Research (START grant) ; European Union (Marie Curie fellowship) ; Lawrence Berkeley National Laboratory (Laboratory Directed Research and Development Program) ; United States. Dept. of Energy (contract no. DE-AC02-05CH11231) ; Alexander von Humboldt-Stiftung (Feodor Lynen fellowship) ; European Commission (AQUTE) ; German-Israeli Foundation for Scientific Research and Development

More than half of the human population currently lives in urban areas and according to the United Nations, cities will be the living space of an additional 2.5 billion people by the year 2050 (UN, 2015b). The proportion and speed of this urban growth increase the pressure on water resources, and this is often seen negatively. However, this challenge can also be a chance to substantially improve the quality of life in urban areas, if we consider how we want to live tomorrow and actively shape our future. As a group of interdisciplinary young scientists authoring the current science policy report, we agreed that we want to live in cities where sustainable, integrated watershed management guarantees public health and environmental safety. This requires sanitation and rainwater management, solutions for dealing with contaminants, such as micropollutants, as well as information flows and public involvement in water management. Integrated watershed management as part of urban planning takes into account interdisciplinary relationships and connects different sectors, for example city administration, health providers and water managers. It also ensures access to sustainable, adaptable, effective and resilient rain and wastewater management, which includes the specific needs of vulnerable groups. Such a rain and wastewater management considers water reuse as a possibility to increase the available water supply. A growing number and increasing concentration of micropollutants in the aquatic environment are a health risk. It is important to understand their fate and effects and to develop appropriate management strategies. In such decision-making processes, all aspects of water management should be included and local stakeholders involved. Moreover, comprehensive and optimized information flows improve the understanding of water-related problems and must be used to help communities to set priorities, take action and assume responsibilities. Education, capacity building and community engagement are particularly important for creating ownership, identification with water resources and environmental consciousness. Further research is needed in these areas to better understand challenges and chances of water management in growing urban areas and to develop scientifically based solutions. This scientific knowledge will build the basis for policy-making and implementation of actions in urban water management. In this way, we believe a better and more desirable urban environment can be achieved for future generations.