Ga-Pt liquid metal catalysts have emerged as promising catalysts, offering improved catalytic performance compared to pure platinum for reactions such as propane dehydrogenation. Previous studies suggest that the active species formed in Ga-Pt catalysts differ from traditional metallic Pt. In this study, we explore multiple potential active Pt species by focusing on the surface-derived electronic and chemical structures assessed via X-ray photoelectron spectroscopy (XPS) and the correlating structural composition analyzed by scanning transmission electron microscopy (STEM). While XPS indicates that Pt is present in different chemical environments, STEM reveals different topographic structures varying from Pt single atom to Pt agglomerates and Ga-Pt intermetallic compounds (IMCs). The variation in the chemical, electronic, and topographic structure of Pt depends on its amount, as well as on the surrounding environment (e.g., gallium-oxide shell versus liquid Ga matrix). Further, XPS and STEM in situ investigations at elevated temperature (T) shed light on the high dynamic surfaces, demonstrating the dissolution of Ga-Pt IMCs due to the enhanced solubility of Pt in Ga with increasing T. The chemical and electronic structure of the Pt species is discussed in conjunction with density-functional theory and molecular dynamics simulations, providing an unprecedented conceptual understanding of Ga-Pt catalysts.

This document is the unedited not peer-reviewed Author’s version of a Submitted Work to Chemistry of Materials. The controlled assembly of supraparticles using spray-drying enables the synthesis of nanoporous materials. Changing the size of the constituent nanoparticles or their agglomeration states provides access to a diverse range of pore frameworks. This turns supraparticles into ideal scaffolds in heterogeneous catalysis. The combination of supraparticles with atomic layer deposition (ALD) as a surface functionalization technique offers excellent control over the deposition of a functional material and its distribution over the scaffold on the nanoscale. This work reports the combination of SiO2 supraparticles as tunable scaffolds and their loading with a platinum-based ALD catalyst. The deliberate adjustment of the scaffold pore framework via spray-drying and its effects on the catalyst deposition are highlighted. Furthermore, varying numbers of Pt ALD cycles are applied to explore the capability of the combinational approach with respect to catalyst loading and Pt efficiency. High-resolution electron microscopy reveals ultra-small Pt clusters deposited on the supraparticles after the very first ALD cycle. Using the hydrogenation of 4-nitrophenol as a demonstration, the impact of the pore framework and the Pt deposition variation in ALD on the catalytic functionality is investigated.

Interest in organic solar cells (OSCs) is constantly rising in the field of photovoltaic devices. The device performance relies on the bulk heterojunction (BHJ) nanomorphology, which develops during the drying process and additional post-treatment. This work investigates the effect of thermal annealing (TA) on the all-small molecule DRCN5T:PC71BM blend with phase field simulations. The objective is to determine the physical phenomena driving the evolution of the BHJ morphology for a better understanding of the post-treatment/morphology relationship. Phase-field simulation results are used to investigate the impact on the final BHJ morphology of the DRCN5T crystallization-related mechanisms, including nucleation, growth, crystal stability, impingement, grain coarsening, and Ostwald ripening, of the amorphous-amorphous phase separation (AAPS), and of diffusion limitations. The comparison of simulation results with experimental data shows that the morphological evolution of the BHJ under TA is dominated by dissolution of the smallest, unstable DRCN5T crystals and anisotropic growth of the largest crystals.

Stainless steel is a possible candidate for replacing titanium-based bipolar plates to reduce the cost of proton exchange membrane water electrolyzers. However, stainless steel is suspected to dissolve which could harm the system. Herein, we investigate the influence of applied potentials and temperatures on the dissolution stability of stainless steel (316L) in deionized (DI) water (pH approximate to 7) and highly diluted H2SO4 (pH approximate to 3) utilizing a scanning flow cell coupled on-line to an inductively coupled plasma mass spectrometer (SFC-ICP-MS). In H2SO4, the applied potentials critically influence the dissolution rates of 316L. Detrimental dissolution is observed at the open circuit potential, whereas dissolution is minimal in a potential window between 0.76 and 0.96 V. Temperature enhances the dissolution of 316L, especially due to a reduced stability of Cr. In DI water, the stability of 316L remains widely independent of potential and temperature, with dissolution rates remaining at an overall low level. Complementary scanning- and transmission electron microscopy reveal corrosion phenomena after electrochemical measurements in pH 3. Our results provide insights into factors influencing the stability of 316L and emphasize the importance of testing conditions that accurately mimic real-operations.

The widespread application of green hydrogen production technologies requires cost reduction of crucial elements. To achieve this, a viable pathway to reduce the iridium loading in proton exchange membrane water electrolysis (PEMWE) is explored. Herein, a scalable synthesis method based on a photodeposition process for a TiO2@IrOx core-shell catalyst with a reduced iridium content as low as 40 wt.% is presented. Using this synthesis method, titania support particles homogeneously coated with a thin iridium oxide shell of only 2.1 +/- 0.4 nm are obtained. The catalyst exhibits not only high ex situ activity, but also decent stability compared to commercially available catalysts. Furthermore, the unique core-shell structure provides a threefold increased electrical powder conductivity compared to structures without the shell. In addition, the low iridium content facilitates the fabrication of sufficiently thick catalyst layers at decreased iridium loadings mitigating the impact of crack formation in the catalyst layer during PEMWE operation. It is demonstrated that the novel TiO2@IrOx core-shell catalyst clearly outperforms the commercial reference in single-cell tests with an iridium loading below 0.3 mg(Ir) cm(-2) exhibiting a superior iridium-specific power density of 17.9 kW g(Ir)(-1) compared to 10.4 kW g(Ir)(-1) for the commercial reference.

Advanced in situ techniques based on electrons and X-rays are increasingly used to gain insights into fundamental processes in liquids. However, probing liquid samples with ionizing radiation changes the solution chemistry under observation. In this work, we show that a radiation-induced decrease in pH does not necessarily correlate to an increase in acidity of aqueous solutions. Thus, pH does not capture the acidity under irradiation. Using kinetic modeling of radiation chemistry, we introduce alternative measures of acidity (radiolytic acidity π* and radiolytic ion product KW*), that account for radiation-induced alterations of both H+ and OH- concentration. Moreover, we demonstrate that adding pH-neutral solutes such as LiCl, LiBr, or LiNO3 can trigger a significant change in π*. This provides a huge parameter space to tailor the acidity for in situ experiments involving ionizing radiation, as present in synchrotron facilities or during liquid-phase electron microscopy.

The digital transformation and consequent use of new digital technologies not only have a substantial impact on society and companies, but also on science. Analog documentation as we have known it for centuries will eventually be replaced by intelligent and FAIR (Findable, Accessible, Interoperable, and Reusable) systems. In addition to the actual research data and results, metadata now plays an important role not only for individual, independently existing projects, but for future scientific use and interdisciplinary research groups and disciplines as well. The solution presented here, consisting of an electronic laboratory notebook and laboratory information management system (ELN-LIMS) based on the openBIS (open Biology Information System) environment, offers interesting features and advantages, especially for interdisciplinary work. The Collaborative Research Centre (CRC) 1411 ‘Design of Particulate Products’ of the German Research Foundation is characterized by the cooperation of different working groups of synthesis, characterization, and simulation, and therefore serves as a model environment to present the implementation of openBIS. OpenBIS, as an open source ELN-LIMS solution following FAIR principles, provides a common set of general entries with the possibility of sharing and linking (meta-)data to improve the scientific exchange between all users.

Journal Article Crystal Structure and Defect Analysis of Colloidal Supraparticles by Lab-Based X-ray Microscopy Get access Silvan Englisch, Silvan Englisch Institute of Micro- and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM), IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Corresponding authors: silvan.englisch@fau.de, erdmann.spiecker@fau.de Search for other works by this author on: Oxford Academic Google Scholar Junwei Wang, Junwei Wang Institute of Particle Technology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Lukas J Roemling, Lukas J Roemling Institute of Particle Technology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Johannes Voß, Johannes Voß Institute of Micro- and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM), IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Janis Wirth, Janis Wirth Institute of Micro- and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM), IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Chrameh Fru Mbah, Chrameh Fru Mbah Institute for Multiscale Simulation, IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Benjamin Apeleo Zubiri, Benjamin Apeleo Zubiri Institute of Micro- and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM), IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Michael Engel, Michael Engel Institute for Multiscale Simulation, IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Nicolas Vogel, Nicolas Vogel Institute of Particle Technology, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Search for other works by this author on: Oxford Academic Google Scholar Erdmann Spiecker Erdmann Spiecker Institute of Micro- and Nanostructure Research (IMN) and Center for Nanoanalysis and Electron Microscopy (CENEM), IZNF, Friedrich-Alexander Universität Erlangen-Nürnberg, Erlangen, Germany Corresponding authors: silvan.englisch@fau.de, erdmann.spiecker@fau.de Search for other works by this author on: Oxford Academic Google Scholar Microscopy and Microanalysis, Volume 28, Issue S1, 1 August 2022, Pages 306–309, https://doi.org/10.1017/S1431927622002008 Published: 01 August 2022

In situ TEM utilizing windowed gas cells is a promising technique for studying catalytic processes, wherein temperature is one of the most important parameters to be controlled. Current gas cells are only capable of temperature measurement on a global (mm) scale, although the local temperature at the spot of observation (µm to nm scale) may significantly differ. Thus, local temperature fluctuations caused by gas flow and heat dissipation dynamics remain undetected when solely relying on the global device feedback. In this study, we overcome this limitation by measuring the specimen temperature in situ utilizing parallel-beam electron diffraction at gold nanoparticles. By combining this technique with an advanced data processing algorithm, we achieve sub-Kelvin precision in both, vacuum as well as gaseous environments. Mitigating charging effects is furthermore shown to minimize systematic errors. By utilizing this method, we characterize the local thermal stability of a state-of-the-art gas cell equipped with heating capability in vacuum and under various gas-flow conditions. Our findings provide crucial reference for in situ investigations into catalysis.

A significant electron-beam induced heating effect is demonstrated for liquid-phase transmission electron microscopy at low electron flux densities using Au nanoparticles as local nanothermometers. The obtained results are in agreement with theoretical considerations. Furthermore, the impact of beam-induced heating on radiolysis chemistry is estimated and the consequences of the effect are discussed.

Nano-/microplastics (NP) is a human-made emerging contaminant with worldwide occurrence. The small size (below one micrometer), the different chemical nature and the persistence make NP to potential hazards with suspect probability of tissue penetration and inflammation or as accumulator for toxins. A strategy to stop the spill of novel NP is the remediation from waste water or rivers as prominent distributors. We have developed core–shell superparamagnetic iron oxide nanoparticles (SPIONs) that attract NP and glue them to larger agglomerates which then can be removed from water by applying an external magnetic field. The shell molecules provide two interaction motifs towards NP. The tuned surface potential of the functionalized SPIONs attract complementary charged NP efficiently and the n-alkyl chain is dedicated to preferential interaction towards organic NP rather than inorganic particles. Structural analytics and molecular dynamics simulation support the proposed concept. Systematic remediation experiments with different NP (chemical structures, sizes and mixtures), from different waters – including river water – and with different SPION core materials indicate a universal validity of the concept, with best remediation performance for mixed NP. We suggest a method for broadband remediation of various NP with simple materials and processes, which both have the potential to be up-scaled.