arXiv subjects

Maximilian Jaugstetter

Publications and source records attributed to Maximilian Jaugstetter.

4 recordsLinked to original sources

arXiv2025

Investigating the Degradation of LATP Solid Electrolyte in High Alkaline Li-$O_2$ Batteries

In this study, we address the challenge of electrolyte degradation in all-solid-state humidified Li-$O_2$ batteries, which offer high theoretical energy density and potential cost advantages over conventional lithium-ion batteries. Combining STEM-EELS, and XPS characterizations with DFT calculations, we reveal the leaching of $(PO_4)^{3+}$ and $Al^{3+}$ ions from the $Li_{1.3}Al_{0.3}Ti_{1.7}(PO_4)_3$ (LATP) solid electrolyte upon battery discharge, caused by the highly alkaline environment. Upon charging, the leached ions precipitate as $Li_3PO_4$ and $AlPO_4$, which accumulate on the LATP surface and contribute to battery degradation. A Ti-rich layer is observed at the surface after a few cycles due to depletion of other cations. Our findings suggest that the degradation products are formed through repeated dissolution and precipitation in the discharge-charge cycles. Furthermore, our results indicate that the Ti-rich layer on the LATP surface can potentially reduce parasitic reactions. Our study provides mechanistic understanding of LATP solid electrolyte degradation in humidified Li-$O_2$ cell, paving the way for designing more durable and efficient Li-$O_2$ batteries.

cond-mat.mtrl-sci↗

arXiv2025

Chemical and Morphological Transformations of a Ag-Cu Nanocatalyst During CO2 Reduction Reaction

The conversion of CO2 into high-value chemicals through a photoreduction reaction in water is a promising route to reduce the dependence on fossil fuels. Ag nanoparticles can drive this reaction via localized surface plasmon resonance, but their low selectivity limits usage in industry. Enhancing selectivity toward hydrocarbons or alcohols requires addition of a co-catalyst such as Cu. However, the stabilized surface state created by Ag-Cu interactions is still poorly understood. In this work, soft x-ray Ambient-Pressure X-ray Photoelectron Spectroscopy (AP-XPS) and Grazing-Incidence X-ray Scattering (AP-GIXS) were used to investigate the evolution of Ag-Cu nanoparticles under CO2RR-like conditions. AP-XPS revealed Ag and Cu surface and sub-surface diffusion, while AP-GIXS tracked change of shape and size of nanoparticles induced by diffusion mechanics. Under 532 nm laser irradiation, further oxidation of Cu and Ag sub-surface diffusion were observed, providing invaluable insights into the dynamic restructuring of the catalyst under reaction conditions.

cond-mat.mtrl-sci↗

arXiv2025

Direct observation of phase change accommodating hydrogen uptake in bimetallic nanoparticles

Hydrogen holds great promise as a cleaner alternative to fossil fuels, but its efficient and affordable storage remains a significant challenge. Bimetallic systems, such as Pd-Ni, present a promising option for storing hydrogen. In this study, using the combination of different cuttingedge X-ray and electron techniques, we observed the transformations of Pd-Ni nanoparticles, which initially consist of a NiO-rich shell surrounding a Pd-rich core but undergo a major transformation when interacting with hydrogen. During the hydrogen exposure, the Pd core breaks into smaller pockets, dramatically increasing its surface area and enhancing the hydrogen storage capacity, especially in nanoparticles with lower Pd content. The findings provide deep understanding of the morphological changes at the atomic level during hydrogen storage and contribute for designing cost-effective hydrogen storage using multi-metallic systems.

cond-mat.mtrl-sci↗

arXiv2024

Direct Observation of Morphological and Chemical Changes During the Oxidation of Model Inorganic Ligand-Capped Particles

Functionalization and volatilization are competing reactions during the oxidation of carbonaceous materials and are important processes in many different areas of science and technology. Here we present a combined ambient pressure X-ray photoelectron spectroscopy (APXPS) and grazing incidence X-ray scattering (GIXS) investigation of the oxidation of oleic acid ligands surrounding NaYF4 nanoparticles (NPs) deposited onto SiOx/Si substrates. While APXPS monitors the evolution of the oxidation products, GIXS provides insight into the morphology of the ligands and particles before and after the oxidation. Our investigation shows that the oxidation of the oleic acid ligands proceeds at O2 partial pressures of below 1 mbar in the presence of X-rays, with the oxidation eventually reaching a steady state in which mainly CHx and -COOH functional groups are observed. The scattering data reveal that the oxidation and volatilization reaction proceeds preferentially on the side of the particle facing the gas phase, leading to the formation of a chemically and morphologically asymmetric ligand layer. This comprehensive picture of the oxidation process could only be obtained by combining the X-ray scattering and APXPS data. The investigation presented here lays the foundation for further studies of the stability of NP layers in the presence of reactive trace gasses and ionizing radiation, and for other nanoscale systems where chemical and morphological changes happen simultaneously and cannot be understood in isolation.

physics.chem-ph↗