Journal article

Publication year: 2024

Pages: 6246-6256

Journal: Chemistry of Materials

Volume number: 36

Issue number: 12

ISSN: 0897-4756

eISSN: 1520-5002

DOI Link: https://doi.org/10.1021/acs.chemmater.4c01084

Publisher: American Chemical Society

Abstract: 
Metal exsolution is a smart strategy that allows modification and enrichment of a material's surface with highly active catalytic phases, thus offering the possibility to fine-tune the surface chemical composition. We study the exsolution of Ru from a perovskite solid solution LaFe0.9Ru0.1O3 (LFRO) to form Ru nanoparticles and their passivation by a conforming LaOx layer by applying a variety of in situ techniques, including TEM and XPS, in combination with ex situ infrared and Raman spectroscopy, but most notably by utilizing the catalytic propane combustion to probe the formation of the passivating LaOx layer. During the Ru exsolution process, Ru3+ in LFRO is reduced first to the Ru-beta species and subsequently into a Ru-0 species, evidencing the exsolution of Ru particle. The transformation of Ru3+ -> Ru-beta proceeds already below 300 degrees C and is correlated with the formation of oxygen vacancies under a reductive atmosphere. The subsequent transformation of Ru-beta toward Ru-0 needs at least a reduction temperature of 400 degrees C that is likely to be determined by the diffusion of Ru3+ from the near-surface region of LFRO toward the surface. Only above 600 degrees C ruthenium cations from the bulk of LFRO are exsolved, leading to the further growth of Ru particles. Around 600 degrees C, the exsolution of Ru particles is accompanied by the formation of a covering LaOx layer. We propose that La segregation and precipitation as surface LaOx are driven by the overstoichiometry of La in LFRO after Ru exsolution.

Harvard Citation style: Wang, Y., Paciok, P., Pielsticker, L., Wang, W., Spriewald Luciano, A., Ding, M., et al. (2024) Microscopic Insight into Ruthenium Exsolution from LaFe0.9Ru0.1O3 Perovskite, Chemistry of Materials, 36(12), pp. 6246-6256. https://doi.org/10.1021/acs.chemmater.4c01084

APA Citation style: Wang, Y., Paciok, P., Pielsticker, L., Wang, W., Spriewald Luciano, A., Ding, M., Glatthaar, L., Hetaba, W., Guo, Y., Gallego, J., Smarsly, B., & Over, H. (2024). Microscopic Insight into Ruthenium Exsolution from LaFe0.9Ru0.1O3 Perovskite. Chemistry of Materials. 36(12), 6246-6256. https://doi.org/10.1021/acs.chemmater.4c01084