Suchergebnisse

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.

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.