@article{64182, abstract = {{Overcoming the slow kinetics of the oxygen evolution reaction at the anode is a key challenge for the production of hydrogen via electrolysis. This reaction operates at very positive potentials, where the electrocatalyst is exposed to highly oxidative conditions and prone to potential-dependent transformation of the near-surface region. While substantial evidence for such surface restructuring exists, its extent and relevance for the catalyst’s activity are unclear. We address this topic for the case of Co3O4, one of the best-known electrocatalysts exhibiting surface restructuring, by studies of epitaxial (111)-ordered electrodeposited films with combined operando X-ray surface diffraction and absorption spectroscopy, electrochemical impedance spectroscopy, and electrochemical measurements on rotating disk electrodes. Comparison of the as-prepared and annealed state of the same samples, which both are stable even under long-term oxygen evolution conditions, provides clear insight into the role of surface defects. Our results show that defect-free annealed Co3O4(111) surfaces are structurally stable over a wide potential range and hydroxylate via adsorption at surface oxygen and Co sites. Potential-induced surface restructuring of the Co3O4 lattice occurs only in the presence of surface defects, leading to the formation of the well-known nanometer-thick oxyhydroxide skin layer. The presence of this skin layer promotes oxygen evolution at low overpotentials but results in higher Tafel slopes. As a result, highly ordered Co3O4(111) surfaces are more active at high current densities than defective Co3O4 surfaces that undergo surface restructuring. These results highlight that strategies for catalyst surface defect engineering need to be application-oriented.}}, author = {{Scharf, Carl Hendric and Chandraraj, Alex and Dyk, Konrad and Stebner, Felix and Lepin, Sören and Tian, Jing and El Bergmi Byaz, Laila and Stettner, Jochim and Leppin, Christian and Kotova, Anastasiia and Reinke, Sebastian and Linnemann, Julia and Maroun, Fouad and Magnussen, Olaf M.}}, issn = {{2155-5435}}, journal = {{ACS Catalysis}}, keywords = {{electrocatalysis, oxygen evolution reaction, cobalt spinel, operando characterization}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Role of Defects in Reversible Surface Restructuring and Activity of Co3O4 Oxygen Evolution Electrocatalysts}}}, doi = {{10.1021/acscatal.5c08785}}, year = {{2026}}, } @article{62798, abstract = {{We investigated electrodeposited nanoparticulate nickel selenide (pre)catalysts that transform into nickel oxides/oxyhydroxides under oxygen evolution reaction conditions in alkaline solutions. Previous studies of this transformation were conducted at lower current densities than those of industrial relevance (≥1 A cm–2). We used ultramicroelectrodes (UMEs) to achieve such current densities, benefiting from their small size, ensuring low absolute currents and low ohmic drop but high current densities. Morphological degradation of the catalyst material was only observed at current densities exceeding 1 A cm–2 but not for smaller ones. Using X-ray absorption, X-ray photoemission spectroscopy, and X-ray diffraction, we confirmed that the degradation was accompanied by the literature-known transformation of nanoparticulate Ni3Se2 (bulk)/NiSe (surface) into nickel oxyhydroxide. The transformation of the precatalyst goes along with a significant improvement in the charge transfer kinetics observed by decreasing Tafel slopes with ongoing experimental time extracted from cyclic voltammetry (CV) experiments and electrochemical impedance spectroscopy (EIS) in the high-frequency range. However, these kinetic improvements are accompanied by limitations in mass transport concluded from decreasing current responses at high overpotentials in CVs and increasing impedance in the low-frequency range of the EIS spectra after extended CV cycling. These mass transport limitations originated from morphological degradations at the UME exceeding 1 A cm–2 which we proved by applying identical location scanning electron microscopy. This has not been reported in studies that have been limited to lower current densities before. Our findings showcase how UMEs can be used to study (pre)catalysts (herein nickel selenides) under current densities of industrial relevance in the absence of ohmic drop-related ambiguities, combined with in-depth materials characterization studies, e.g., identical location microscopy and advanced spectroscopic methods. This approach enables direct evaluation and comparison of catalyst materials and thus demonstrates how to overcome long-standing limitations of electrocatalyst design and testing.}}, author = {{Hiege, Felix and Chang, Chun-Wai and Trost, Oliver and van Halteren, Charlotte E. R. and Hosseini, Pouya and Bendt, Georg and Schulz, Stephan and Feng, Zhenxing and Linnemann, Julia and Tschulik, Kristina}}, issn = {{1944-8244}}, journal = {{ACS Applied Materials & Interfaces}}, keywords = {{Electrocatalysis, oxygen evolution reaction, nickel selenide, microelectrode}}, number = {{29}}, pages = {{41893--41903}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Morphological Degradation of Oxygen Evolution Reaction-Electrocatalyzing Nickel Selenides at Industrially Relevant Current Densities}}}, doi = {{10.1021/acsami.5c05381}}, volume = {{17}}, year = {{2025}}, } @article{61982, abstract = {{Doped Co3O4 nanoparticles are investigated via spectro-electrochemistry in the (pre-) oxygen evolution reaction (OER) regime by tracing the absorption signal of the Co3+ d–d transition under applied bias for getting insight into the catalysts activation and the formation of catalytically active phases. In the low potential regime up to 1.37 VRHE, a rise in the optical absorption signal of the [Co3+]oct d–d transition is observed and attributed to a structural change from [Co2+]tet to [Co3+]oct due to an electrochemically induced surface restructuring with water. For applied potentials higher than 1.37 VRHE an overall offset of the absorption spectra in the UV–vis range, equivalent to a darkening of the materials is detected. This is attributed to the formation of a CoOx(OH)y skin layer as supported by high-energy X-ray diffraction (HE-XRD) measurements. We found that the kinetics of the Co3+ states are heavily influenced by the type of dopant with V-doped Co3O4 exhibiting stable Co3+ states (>20 min) while the Mn-doped Co3O4 Co3+ states reduce within 36 s under reductive bias. We conclude that doping Co3O4 with transition metals affects the formation and potential-dependent thickness of the CoOx(OH)y skin layer as the catalytically active phase and the formation of long-time stable surface Co3+ states after activation in the first OER cycle.}}, author = {{Kampermann, L. and Klein, J. and Wagner, T. and Kotova, A. and Placke-Yan, C. and Yasar, A. and Jacobse, L. and Lasagna, S. and Leppin, Christian and Schulz, S. and Linnemann, Julia and Bergmann, A. and Roldan Cuenya, B. and Bacher, G.}}, issn = {{2155-5435}}, journal = {{ACS Catalysis}}, keywords = {{electrocatalysis, oxygen evolution reaction, cobalt spinel, operando characterization, spectroelectrochemistry}}, number = {{21}}, pages = {{18391--18403}}, publisher = {{American Chemical Society (ACS)}}, title = {{{Operando Analysis of the Pre-OER Activation of Metal-Doped Co3O4 Nanoparticle Catalysts}}}, doi = {{10.1021/acscatal.5c03900}}, volume = {{15}}, year = {{2025}}, } @article{45857, abstract = {{The aim of the present study is to prove the construct validity of the German versions of the Feeling Scale (FS) and the Felt Arousal Scale (FAS) for a progressive muscle relaxation (PMR) exercise. A total of 228 sport science students conducted the PMR exercise for 45 min and completed the FS, the FAS, and the Self-Assessment Manikin (SAM) in a pre-test–post-test design. A significant decrease in arousal (t(227) = 8.296, p < 0.001) and a significant increase in pleasure (t(227) = 4.748, p < 0.001) were observed. For convergent validity, the correlations between the FS and the subscale SAM-P for the valence dimension (r = 0.67, p < 0.001) and between the FAS and the subscale SAM-A for the arousal dimension (r = 0.31, p < 0.001) were significant. For discriminant validity, the correlations between different constructs (FS and SAM-A, FAS and SAM-P) were not significant, whereas the discriminant analysis between the FS and the FAS revealed a negative significant correlation (r = −0.15, p < 0.001). Together, the pattern of results confirms the use of the German versions of the FS and the FAS to measure the affective response for a PMR exercise.}}, author = {{Thorenz, Kristin and Berwinkel, Andre and Weigelt, Matthias}}, issn = {{2076-328X}}, journal = {{Behavioral Sciences}}, keywords = {{Behavioral Neuroscience, General Psychology, Genetics, Development, Ecology, Evolution, Behavior and Systematics}}, number = {{7}}, publisher = {{MDPI AG}}, title = {{{A Validation Study for the German Versions of the Feeling Scale and the Felt Arousal Scale for a Progressive Muscle Relaxation Exercise}}}, doi = {{10.3390/bs13070523}}, volume = {{13}}, year = {{2023}}, } @article{62810, abstract = {{Cobalt iron containing layered double hydroxides (LDHs) and spinels are promising catalysts for the electrochemical oxygen evolution reaction (OER). Towards development of better performing catalysts, the precise tuning of mesostructural features such as pore size is desirable, but often hard to achieve. Herein, a computer‐controlled microemulsion‐assisted co‐precipitation (MACP) method at constant pH is established and compared to conventional co‐precipitation. With MACP, the particle growth is limited and through variation of the constant pH during synthesis the pore size of the as‐prepared catalysts is controlled, generating materials for the systematic investigation of confinement effects during OER. At a threshold pore size, overpotential increased significantly. Electrochemical impedance spectroscopy (EIS) indicated a change in OER mechanism, involving the oxygen release step. It is assumed that in smaller pores the critical radius for gas bubble formation is not met and therefore a smaller charge‐transfer resistance is observed for medium frequencies.}}, author = {{Rabe, Anna and Jaugstetter, Maximilian and Hiege, Felix and Cosanne, Nicolas and Ortega, Klaus Friedel and Linnemann, Julia and Tschulik, Kristina and Behrens, Malte}}, issn = {{1864-5631}}, journal = {{ChemSusChem}}, keywords = {{electrocatalysis, oxygen evolution reaction, cobalt spinel, cobalt hydroxide, LDH}}, number = {{10}}, publisher = {{Wiley}}, title = {{{Tailoring Pore Size and Catalytic Activity in Cobalt Iron Layered Double Hydroxides and Spinels by Microemulsion‐Assisted pH‐Controlled Co‐Precipitation}}}, doi = {{10.1002/cssc.202202015}}, volume = {{16}}, year = {{2023}}, } @article{62801, abstract = {{The three-dimensional (3D) distribution of individual atoms on the surface of catalyst nanoparticles plays a vital role in their activity and stability. Optimising the performance of electrocatalysts requires atomic-scale information, but it is difficult to obtain. Here, we use atom probe tomography to elucidate the 3D structure of 10 nm sized Co2FeO4 and CoFe2O4 nanoparticles during oxygen evolution reaction (OER). We reveal nanoscale spinodal decomposition in pristine Co2FeO4. The interfaces of Co-rich and Fe-rich nanodomains of Co2FeO4 become trapping sites for hydroxyl groups, contributing to a higher OER activity compared to that of CoFe2O4. However, the activity of Co2FeO4 drops considerably due to concurrent irreversible transformation towards CoIVO2 and pronounced Fe dissolution. In contrast, there is negligible elemental redistribution for CoFe2O4 after OER, except for surface structural transformation towards (FeIII, CoIII)2O3. Overall, our study provides a unique 3D compositional distribution of mixed Co-Fe spinel oxides, which gives atomic-scale insights into active sites and the deactivation of electrocatalysts during OER.}}, author = {{Xiang, Weikai and Yang, Nating and Li, Xiaopeng and Linnemann, Julia and Hagemann, Ulrich and Ruediger, Olaf and Heidelmann, Markus and Falk, Tobias and Aramini, Matteo and DeBeer, Serena and Muhler, Martin and Tschulik, Kristina and Li, Tong}}, issn = {{2041-1723}}, journal = {{Nature Communications}}, keywords = {{electrocatalysis, oxygen evolution reaction, cobalt spinel, electrochemical impedance spectroscopy}}, number = {{1}}, publisher = {{Springer Science and Business Media LLC}}, title = {{{3D atomic-scale imaging of mixed Co-Fe spinel oxide nanoparticles during oxygen evolution reaction}}}, doi = {{10.1038/s41467-021-27788-2}}, volume = {{13}}, year = {{2022}}, } @article{22220, abstract = {{Abstract Developing resource-abundant and sustainable metal-free bifunctional oxygen electrocatalysts is essential for the practical application of zinc–air batteries (ZABs). 2D black phosphorus (BP) with fully exposed atoms and active lone pair electrons can be promising for oxygen electrocatalysts, which, however, suffers from low catalytic activity and poor electrochemical stability. Herein, guided by density functional theory (DFT) calculations, an efficient metal-free electrocatalyst is demonstrated via covalently bonding BP nanosheets with graphitic carbon nitride (denoted BP-CN-c). The polarized PN covalent bonds in BP-CN-c can efficiently regulate the electron transfer from BP to graphitic carbon nitride and significantly promote the OOH* adsorption on phosphorus atoms. Impressively, the oxygen evolution reaction performance of BP-CN-c (overpotential of 350 mV at 10 mA cm−2, 90\% retention after 10 h operation) represents the state-of-the-art among the reported BP-based metal-free catalysts. Additionally, BP-CN-c exhibits a small half-wave overpotential of 390 mV for oxygen reduction reaction, representing the first bifunctional BP-based metal-free oxygen catalyst. Moreover, ZABs are assembled incorporating BP-CN-c cathodes, delivering a substantially higher peak power density (168.3 mW cm−2) than the Pt/C+RuO2-based ZABs (101.3 mW cm−2). The acquired insights into interfacial covalent bonds pave the way for the rational design of new and affordable metal-free catalysts.}}, author = {{Wang, Xia and Kormath Madam Raghupathy, Ramya and Querebillo, Christine Joy and Liao, Zhongquan and Li, Dongqi and Lin, Kui and Hantusch, Martin and Sofer, Zdeněk and Li, Baohua and Zschech, Ehrenfried and Weidinger, Inez M. and Kühne, Thomas and Mirhosseini, Hossein and Yu, Minghao and Feng, Xinliang}}, journal = {{Advanced Materials}}, keywords = {{2D materials, bifunctional oxygen electrocatalysts, black phosphorus, oxygen evolution reaction, zinc–air batteries}}, number = {{20}}, pages = {{2008752}}, title = {{{Interfacial Covalent Bonds Regulated Electron-Deficient 2D Black Phosphorus for Electrocatalytic Oxygen Reactions}}}, doi = {{https://doi.org/10.1002/adma.202008752}}, volume = {{33}}, year = {{2021}}, } @article{62805, abstract = {{Single-entity electrochemistry allows for assessing electrocatalytic activities of individual material entities such as nanoparticles (NPs). Thus, it becomes possible to consider intrinsic electrochemical properties of nanocatalysts when researching how activity relates to physical and structural material properties. Conversely, conventional electrochemical techniques provide a normalized sum current referring to a huge ensemble of NPs constituting, along with additives (e.g., binders), a complete catalyst-coated electrode. Accordingly, recording electrocatalytic responses of single NPs avoids interferences of ensemble effects and reduces the complexity of electrocatalytic processes, thus enabling detailed description and modelling. Herein, we present insights into the oxygen evolution catalysis at individual cubic Co3O4 NPs impacting microelectrodes of different support materials. Simulating diffusion at supported nanocubes, measured step current signals can be analyzed, providing edge lengths, corresponding size distributions, and interference-free turnover frequencies. The provided nano-impact investigation of (electro-)catalyst-support effects contradicts assumptions on a low number of highly active sites.}}, author = {{Liu, Zhibin and Corva, Manuel and Amin, Hatem M. A. and Blanc, Niclas and Linnemann, Julia and Tschulik, Kristina}}, issn = {{1422-0067}}, journal = {{International Journal of Molecular Sciences}}, keywords = {{electrocatalysis, oxygen evolution reaction, cobalt spinel, single-entity electrochemistry}}, number = {{23}}, publisher = {{MDPI AG}}, title = {{{Single Co3O4 Nanocubes Electrocatalyzing the Oxygen Evolution Reaction: Nano-Impact Insights into Intrinsic Activity and Support Effects}}}, doi = {{10.3390/ijms222313137}}, volume = {{22}}, year = {{2021}}, } @article{34829, author = {{Hanusch, Maximilian}}, issn = {{1435-5337}}, journal = {{Forum Mathematicum}}, keywords = {{regularity of Lie groups, differentiability of the evolution map}}, number = {{5}}, pages = {{1139--1177}}, publisher = {{Walter de Gruyter GmbH}}, title = {{{Differentiability of the evolution map and Mackey continuity}}}, doi = {{10.1515/forum-2018-0310}}, volume = {{31}}, year = {{2019}}, } @article{58528, author = {{Jansen, Gunther and Crummenerl, Lena Luise and Gilbert, Felix and Mohr, Timm and Pfefferkorn, Roxana and Thänert, Robert and Rosenstiel, Philip and Schulenburg, Hinrich}}, journal = {{Molecular Biology and Evolution}}, keywords = {{symbiosis, experimental evolution, Pseudomonas, immunocompromised, evolutionary transition, commensalism, global regulator, lasR}}, number = {{11}}, pages = {{2883--2896}}, title = {{{Evolutionary Transition from Pathogenicity to Commensalism: Global Regulator Mutations Mediate Fitness Gains through Virulence Attenuation}}}, doi = {{10.1093/molbev/msv160}}, volume = {{32}}, year = {{2015}}, } @inproceedings{9870, abstract = {{Nowadays wire bonding is a widely-used technology for interconnecting chips in the packaging industry. Thereby, it is known that the bond quality massively depends upon the microstructure prevailing in the bond and consequently the materials used as well as the bonding parameters. However the actually used materials such as aluminum and gold are either characterized by comparibly poor conductivity or high costs, respectively. Due to its outstanding properties copper is a more attractive candidate. Still, a thorough investigation on the interrelationship between the material combinations, the processing parameters and the resulting microstructure for copper and aluminum wire bonding was not carried out yet. Depending on the aforementioned factors the microstructural evolution can be completely different during the bonding process. Therefore, this study focuses on the microstructural evolution of heavy copper and heavy aluminum wires bonded on copper substrates. The evolution of the wire microstructure as well as the wire-substrate-interface was investigated by scanning electron microscope in combination with electron backscatter diffraction and microhardness measurements. Various samples were extracted at different points of the bonding process, namely the as-received condition, after touchdown and after completed bonding. The results of the aluminum and copper wires were compared to each other in both longitudinal and transversal direction. It was found, that the two wire materials were completely different in the as-received condition regarding the grain size, the grain morphology, the texture and the microhardness. After touchdown the microstructure did not show significant changes in both materials, yet a strain-hardening was observed in the copper wire resulting from the touchdown force. When the bonding process was completed a different microstructure could be observed in both the wire as well as the layer for the materials investigated. Furthermore, a destinctive increase in the wire hardness could be found in case of copper, which was not observed for the aluminum wire. The ramifications between the two wire materials presented in this work will be discussed with the objective of optimizing the quality of the bonds.}}, author = {{Eacock , Florian and Schaper, Mirko and Althoff, Simon and Unger, Andreas and Eichwald, Paul and Hengsbach, Florian and Zinn, Carolin and Holzweissig, Martin Joachim and Guth, Karsten}}, booktitle = {{Proceedings of the 47th International Symposium on Microelectronics}}, keywords = {{Bonding, Copper, Microstructure evolution}}, title = {{{Microstructural investigations of aluminum and copper wire bonds}}}, doi = {{10.4071/isom-THP32}}, year = {{2014}}, } @inproceedings{6508, abstract = {{In this paper, we present a framework that supports experimenting with evolutionary hardware design. We describe the framework's modules for composing evolutionary optimizers and for setting up, controlling, and analyzing experiments. Two case studies demonstrate the usefulness of the framework: evolution of hash functions and evolution based on pre-engineered circuits.}}, author = {{Kaufmann, Paul and Platzner, Marco}}, booktitle = {{Second NASA/ESA Conference on Adaptive Hardware and Systems (AHS 2007)}}, isbn = {{076952866X}}, keywords = {{integrated circuit design, hardware evolution, evolutionary hardware design, evolutionary optimizers, hash functions, preengineered circuits, Hardware, Circuits, Design optimization, Visualization, Genetic programming, Genetic mutations, Clustering algorithms, Biological cells, Field programmable gate arrays, Routing}}, location = {{Edinburgh, UK}}, pages = {{447--454}}, publisher = {{IEEE}}, title = {{{MOVES: A Modular Framework for Hardware Evolution}}}, doi = {{10.1109/ahs.2007.73}}, year = {{2007}}, }