Date/Time: 04-24-2019 - Wednesday - 05:00 PM - 07:00 PM
Joshua Vincent1 Peter Crozier1

1, Arizona State University, Tempe, Arizona, United States

In heterogeneous catalysis, metal-support interactions can lead to enhanced catalytic performance. Cu and Pt nanoparticles supported on CeO2, for example, are more active for CO oxidation than those supported on non-reducible metal oxides (such as SiO2 [1]). The enhancement arises from CeO2’s ability to locally donate oxygen at the metal-support interface, through a Mars van Krevelen-like mechanism. The ease with which oxygen may be removed from the CeO2 lattice has been shown theoretically to depend on the atomic structure of the metal-support interface [2]. At present, though, there is little experimental data on the atomic structures that comprise the metal-support interface during catalysis. Correspondingly, many important questions remain as to what interfacial or proximal surface structures participate in or enhance interfacial oxygen transfer.

In the present study, we seek to elucidate the cooperative atomic-scale dynamics that occur at the metal-support interface during catalysis. The CO oxidation reaction (CO + ½ O2 -> CO2) will be employed as a probe for catalytic activity, due to its chemical simplicity and relevance to clean energy conversion. Nanostructured CeO2 will be used as a model support, and Pt nanoparticles will be loaded onto them through conventional impregnation methods. A quartz tube reactor coupled to a gas chromatograph will be used to determine turn-over frequencies and activation energies for the catalyst, informing the reaction space to be explored during environmental transmission electron microscopy (ETEM) experiments. Aberration-corrected ETEM (AC-ETEM) will be used to visualize the atomic structures that form in reaction conditions. Operando electron energy-loss spectroscopy will be implemented to track the gas composition during catalysis, allowing catalytic activity to be correlated directly with the observed surface and interfacial structures.

The results of these experiments will provide operando information on the interfacial and surface structures that correlate with activity for an important clean energy conversion reaction. These relationships are of fundamental interest to the heterogeneous catalysis community, and they may facilitate the engineering of highly active Pt/CeO2 catalysts for the energy and environmental remediation applications where they are indispensably used [3].

[1] Jia, A.-P., et al; Journal of Physical Chemistry C 114, 21605-10 (2010).
[2] Vayssilov et al; Nature Materials 10, 310–315 (2011).
[3] We gratefully acknowledge support of NSF grant CBET-1604971 and use of facilities at Arizona State University’s John M. Cowley Center for High Resolution Electron Microscopy.

Meeting Program

Symposium Sessions

5:00 PM–7:00 PM Apr 24, 2019 (US - Arizona)

PCC North, 300 Level, Exhibit Hall C-E