July/August

Picture of the Month - July/August 2021

Ruthenium-Iridium Mixed Oxides as Promising Catalyst Materials

The Pechini sol-gel method allows ruthenium dioxide and iridium dioxide to be mixed at the atomic scale to form promising materials for heterogeneously catalyzed oxidation reactions such as the total oxidation of CO and methane. X-ray diffraction reveals the successful intermixture of ruthenium and iridium at atomic level and X-ray photoelectron spectroscopy experiments allow for examining of the catalytic active surface area. The product yield (space time yield) is normalized to the number of active noble metal sites for proper comparison of the intrinsic activities. The mixed oxides Ru_xIr_1-xO₂ show improved catalytic performance for both the prototypic CO oxidation (Ru_0.875Ir_0.125O₂) and the more complex methane combustion (Ru_0.25Ir_0.75O₂), thus revealing a synergistic effect of ruthenium and iridium. For the methane combustion iridium oxide is able to activate the C-H bond at low temperatures, while ruthenium dioxide is a superior oxidation catalyst for the further oxidation of methane fragments.

Publications:

• O. Khalid, T. Weber, G. Drazic, I. Djerdj, and H. Over, Journal of Physical Chemistry C, 2020, 124, 18670-18683, DOI: 10.1021/acs.jpcc.0c06392.
• O. Khalid, A. Spriewald Luciano, G. Drazic, and H. Over, 2021, submitted to ChemCatChem, 2020.

This picture was submitted by Prof. Dr. Herbert Over.

Further insights into the research activities of the ZfM groups can be found in the Gallery.