The imaging of active nanoparticles represents a milestone in decoding heterogeneous catalysts’ dynamics. We report the facet-resolved, surface strain state of a single PtRh alloy nanoparticle on SrTiO3 determined by coherent x-ray diffraction imaging under catalytic reaction conditions. Density functional theory calculations allow us to correlate the facet surface strain state to its reaction environment–dependent chemical composition. We find that the initially Pt-terminated nanoparticle surface gets Rh-enriched under CO oxidation reaction conditions. The local composition is facet orientation dependent, and the Rh enrichment is nonreversible under subsequent CO reduction. Tracking facet-resolved strain and composition under operando conditions is crucial for a rational design of more efficient heterogeneous catalysts with tailored activity, selectivity, and lifetime.
Bibliographical noteFunding Information:
Funding from the European Union H2020 project “Nanoscience Foundries and Fine Analysis” (NFFA), grant no. 654360, from BMBF grant 5K13WC3 (PT-DESY), and from DFG SFB 1441 prefunding is acknowledged. This work was supported by the Helmholtz Association Initiative and Networking Fund (grant no. HRSF-0002), the Russian Science Foundation (grant no. 18-41-06001), and the state of Baden-Württemberg through bwHPC (bwUniCluster and JUSTUS, RV bw17D011).
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