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Nina S. Genz, Antti-Jussi Kallio, et al., Operando Laboratory-based Multi-edge X-ray Absorption Near-Edge Spectroscopy of Solid Catalysts, Angew. Chem. Int. ed. pre-release ahead of print.
In this article, we report the application of multiple x-ray absorption edge (Ni, Cu, and Fe K-edges) study of mono-, bi-, and trmetallic solid-state catalysts using laboratory-scale instrumentation (the HelXAS instrument).
Figure 1. Photograph (a) and scheme (b) of the main components of the new operando laboratory-based XANES setup, including the self-designed motorized crystal exchanger (c), the ex situ sample wheel located in front of the X-ray source (d), and the self-designed motorized sample cell stage (e) for mounting the capillary cell in front of the slit upstream from the detector.
The laboratory-based setup for performing operando, quasi-simultaneous XANES analysis at multiple K edges, which is described in your article, will certainly be of benefit to a large community. Moreover, we have noticed your group’s enthusiasm for collaboration, and engagement with important societal and scientific issues of our times.
— The Editors of Angew. Chem. Int. Ed.
José Moya-Cancino et al., in two consecutive journal articles in ChemCatChem (DOI: 10.1002/cctc.201801822 and DOI: 10.1002/cctc.201900434) show beautifully that operando experiments in catalytic reactor can be performed and new information on Co/TiO2 based Fisher-Tropsch catalysis can be obtained. The aim of the study is to elucidate the catalyst deactivation mechanisms, in particular the role of the formation of cobalt carbides species in the reactor in the deactivation.
This way, our facility was the first to show that operando catalysis experiments are feasible using home-laboratory XAS. The proof-of-concept was congratulated in a recent review by Zimmermann et al. in "Modern X-ray spectroscopy: XAS and XES in the laboratory", published in Coordination Chemistry Reviews 423 (2020), 213466, who write: “Moya-Cancino et al. reported in January 2019 the ﬁrst laboratory-based in situ XANES of a solid Fischer–Tropsch synthesis catalyst (Co/TiO2). This very exciting experiment is using the setup described above by Honkanen et al.” And: “This is an important step forward towards lab-based in situ and operando studies, which is not only relevant for chemistry, but many applications in research often require studies under in situ or operando conditions to understand the dynamics of the process.”
Very nice work! in-situ catalyst cells in our lab XAFS systems is a key goal for 2019. This team did a great job. https://t.co/uA9olzSWiH
— easyXAFS (@easyXAFS) January 12, 2019
In-situ X-ray absorption near edge structure spectroscopy of a solid catalyst using a laboratory-based set-up from @UniUtrecht @helsinkiuni @esrfsynchrotron @IsmnCnr https://t.co/27P2x1LWEm pic.twitter.com/5Hkd651mlq
— ChemCatChem (@ChemCatChem) January 12, 2019
Katja Lahtinen et al., in their publication in Materials Today Energy, entitled "Long term cycling behavior of Mg-doped LiCoO2 materials investigated with the help of laboratory scale X-ray absorption near-edge spectroscopy", show how our infrastructure is able to provide long-term experimental time for XANES in studies of Li-ion battery materials ageing. LiCoO2-based materials with different doping were investigate in a series of experiments that took more than a year to conduct. This would have not been feasible using synchrotron light sources for a regular user.
In the article, Lahtinen et al. show how Mg-doping and overlithiation affect the ageing of the battery cathode material. The maximum reachable Co valence state is found to decrease upon aging, a small decrease indicating a good cycle-life, and this is attributed to the enhanced stacking order, better Mg distribution in the lattice, and fine primary particle size in the material. In the synthesis conditions used in this study, Mg doping during the lithiation step is shown to perform better compared to the precursor doping. Overlithiation is shown to reduce the electrochemical performance of nondoped and precursor-doped LiCoO2 materials but not to affect the cyclability of lithiation-doped LiCoO2.
René Bes et al., in the article in Journal of Nuclear Materials 507 (2018) 50-53 show that actinide research using laboratory-scale XAS (in this case on U L3 edge) is possible. This helps to many challenges related to e.g., transport of radioactive materials to synchrotrons which has been up to now a major bottleneck in actinide research.