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- 2023 (6) (entfernen)
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- Corrosion (2)
- C-F bond activation (1)
- Catalysis (1)
- Compositional complex alloys (1)
- Degradation mechanisms (1)
- Depth resolved XANES (1)
- Dispersive XAS (1)
- Energy storage (1)
- Environmental impacts (1)
- Extended X-ray absorption fine structure (1)
Organisationseinheit der BAM
- 6 Materialchemie (5)
- 6.3 Strukturanalytik (5)
- 3 Gefahrgutumschließungen; Energiespeicher (1)
- 3.6 Elektrochemische Energiematerialien (1)
- 6.1 Oberflächen- und Dünnschichtanalyse (1)
- 6.5 Synthese und Streuverfahren nanostrukturierter Materialien (1)
- 8 Zerstörungsfreie Prüfung (1)
- 8.5 Röntgenbildgebung (1)
- 9 Komponentensicherheit (1)
- 9.2 Versuchsanlagen und Prüftechnik (1)
Paper des Monats
- ja (1)
In this study, we propose the use of nondestructive, depth-resolved, element-specific characterization using grazing exit X-ray absorption near-edge structure spectroscopy (GE-XANES) to investigate the corrosion process in compositionally complex alloys (CCAs). By combining grazing exit X-ray fluorescence spectroscopy (GE-XRF) geometry and a pnCCD detector, we provide a scanning-free, nondestructive, depth-resolved analysis in a sub-micrometer depth range, which is especially relevant for layered materials, such as corroded CCAs. Our setup allows for spatial and energy-resolved measurements and directly extracts the desired fluorescence line, free from scattering events and other overlapping lines. We demonstrate the potential of our approach on a compositionally complex CrCoNi alloy and a layered reference sample with known composition and specific layer thickness. Our findings indicate that this new GE-XANES approach has exciting opportunities for studying surface catalysis and corrosion processes in real-world materials.
With increasing demand and environmental concerns, researchers are exploring new materials that can perform as well or better than traditional materials while reducing environmental impact. The BAMline, a real-life sample materials research beamline, provides unique insights into materials’ electronic and chemical structure at different time and length scales. The beamline specializes in x-ray absorption spectroscopy, x-ray fluorescence spectroscopy, and tomography experiments. This enables real-time optimization of material properties and performance for various applications, such as energy transfer, energy storage, catalysis, and corrosion resistance. This paper gives an overview of the analytical methods and sample environments of the BAMline, which cover non-destructive testing experiments in materials science, chemistry, biology, medicine, and cultural heritage. We also present our own synthesis methods, processes, and equipment developed specifically for the BAMline, and we give examples of synthesized materials and their potential applications. Finally, this article discusses the future perspectives of the BAMline and its potential for further advances in sustainable materials research.
We present how mesoporosity can be engineered in transition metal phosphate (TMPs) materials in a template-free manner. The method involves a transformation of a precursor metal phosphate phase, called M-struvite (NH4MPO4·6H2O, M = Mg2+, Ni2+, Co2+, NixCo1-x2+). It relies on the thermal decomposition of crystalline M-struvite precursors to an amorphous and simultaneously mesoporous phase, which forms while degassing of NH3 and H2O. The temporal evolution of mesoporous frameworks and the response of the metal coordination environment were followed with in-situ and ex-situ scattering and diffraction, as well as X -ray spectroscopy. Despite sharing the same precursor struvite structure, different amorphous and mesoporous structures were obtained depending on the involved transition metal. We highlight the systematic differences in absolute surface area, pore shape, pore size, and phase transitions depending on a metal cation present in the analogous M-struvites. The amorphous structures of thermally decomposed Mg-, Ni- and NixCo1-x-struvites exhibit high surface areas and pore volumes (240 m²g-1 and 0.32 cm-3 g-1 for Mg and 90 m²g-1 and 0.13 cm-3 g-1 for Ni). We propose that the low-cost, environmentally friendly M-struvites could be obtained as recycling products from industrial and agricultural wastewaters. These waste products could be then upcycled into mesoporous TMPs through a simple thermal treatment for further applications, for instance, in (electro)catalysis.
Atomically dispersed metal-nitrogen doped carbons (M-N-C) are
promising catalysts for the activation of small molecules such as O2
and CO2. These single atom catalysts (SAC) operate at the interface
between homogenous and heterogenous catalysts. Currently, many
examples of M-N-C are known with good oxygen reduction reaction
activity but lacking a controlled synthesis of the specific active sites of
the precatalyst. Recently, our group facilitated the synthesis of pure
pyrrolic M-N4 sites using Zn ions as imprinters.[1] These amorphous
materials obtained by active site imprinting method are characterized
at the BAMline (Bessy II) by X-ray absorption spectroscopy (XAS).
In-situ/operando measurements will be crucial in future work for a
better understanding of the dynamic changes of the active site.
An amorphous Lewis-acidic zirconium chlorofluoride as HF shuttle: C–F bond activation and formation
(2023)
An exceptional HF transfer reaction by C–F bond activation of fluoropentane and a subsequent hydrofluorination of alkynes at room temperature is reported. An amorphous Lewis-acidic Zr chlorofluoride serves as heterogeneous catalyst, which is characterised by an eightfold coordination environment at Zr including chlorine atoms. The studies are seminal in establishing sustainable fluorine chemistry.