Session: General Catalysis:

The active sites for single-atom catalysts (SACs) remain highly debated, and fundamental insights are limited due to experimental challenges. We used CO oxidation over metals like Ni, Pd and Pt supported on ceria as a test case for understanding the role and effectiveness of different metal SACs. DFT calculations in conjugation with experiments examine the variation of catalytic performance across the metals and identify the synergy between individual metal atoms and the support towards CO oxidation. Also, since oxidation reactions consume oxygen, the oxidation state of the metal sites as well as specific metal-support interactions are crucial in understanding and predicting the catalytic performance. Therefore, more broadly than understanding CO oxidation, we evaluate the active site, catalyst oxidation state, and reaction mechanism under working conditions of SACs, by leveraging first-principles calculations and spectroscopic experimental techniques. Further on, we also introduce first-principles microkinetic modeling of CO oxidation over the metal atoms to provide further insights into the dynamic states of single atoms under reaction conditions. This is especially important for single-atom catalysts whose reaction mechanism is less established and different from the one of extended surfaces. Together we gather evidence for correlation between active single atom states and the resulting variation in kinetics across Ni, Pd, Pt single atoms and those previously reported over extended surfaces/nanoclusters.

Michael Janik

Appearances