Exploring catalytic reactions from the ensemble average to the single particle limit using X-rays and scanning probe microscopy

Zoom webinar

Andreas Stierle,
Deutsches Elektronen Synchrotron DESY and Universität Hamburg

Oxide supported metal nanoparticles play a crucial role as heterogeneous catalysts for many reactions. In conventional x-ray diffraction (XRD) experiments on powder samples the structural analysis is hampered by a random nanoparticle orientation and often by background scattering from the supporting material. We have therefore investigated epitaxial metal nanoparticles on single crystal oxide supports, which are stable under ambient pressure catalytic reaction conditions. The surface sensitive x-ray diffraction experiments deliver quantitative information on the nanoparticle size, shape and facet surface structures under near ambient pressure operando CO oxidation conditions [1,2]. We have identified active phases for CO oxidation at PtRh nanoparticle surface facets and reaction induced nanoparticle shape transformations. To bridge the gap to powder catalyst material, we have performed operando single nanoparticle diffraction imaging experiments allow the surface composition determination under reaction conditions [3].

[1] U. Hejral, P. Müller, O. Balmes, D. Pontoni, A. Stierle, (2016): Tracking the shape-dependent sintering of platinum-rhodium model catalysts under operando conditions. Nat. Comm. 7, p. 10964. DOI: 10.1038/ncomms10964.
[2] U. Hejral, D. Franz, S. Volkov, S. Francoual, J. Strempfer, A. Stierle, (2018): Identification of a Catalytically Highly Active Surface Phase for CO Oxidation over PtRh Nanoparticles under Operando Reaction Conditions. In Phys. Rev. Lett. 120 (12), p. 126101. DOI: 10.1103/PhysRevLett.120.126101.
[3] Y. Y. Kim, T. F. Keller, T. J. Goncalves, M. Abuin, H. Runge, L. Gelisio J. Carnis, V. Vonk, P. N. Plessow, I. A. Vartaniants, A. Stierle (2021): Single alloy nanoparticle x-ray imaging during a catalytic reaction. In Science Advances 7. DOI: 10.18419/OPUS-6697.