Designing Advanced Nanocatalysts by Looking at Atoms and Molecules on Reactive Surfaces

Clarification of the nature of active sites at both solid-gas and solid-liquid interfaces has been a long-standing question in surface chemistry, holding paramount significance in crafting innovative catalytic materials that demand minimal energy consumption. A bimetallic Pt alloy, or mixed catalyst, is an excellent platform to uncover the contentious role of the metalâ€"metal oxide interface because the alloyed transition metal can coexist with the Pt surface layer in the form of an oxidized species on the bimetal surface during catalytic reactions. The real-time imaging of catalytically reactive atomic sites using operando surface techniques, including ambient pressure scanning tunneling microscopy, can reveal the nature of reactive sites on the catalytic surfaces.

In this talk, I present in-situ observation results of structural modulation on Pt-based bimetal catalysts and mixed catalysts and its impact on the catalytic activity. We utilized PtNi, and PtCo that includes both single crystal and nanoparticle surfaces as model catalysts, and showed the coexistence of Pt and metal oxide leads to the enhancement of catalytic activity, indicating these metal-oxide interfaces provide a more-efficient reaction path for CO oxidation. The mixed catalysts composed of Pt nanoparticles and the mesoporous cobalt oxide exhibit the enhancement of catalytic activity while Pt is encapsulated by the oxide thin layers forming the reactive metal-oxide interfaces. In addition, we address the fundamentals of the electrocatalytic process and on locating the real active sites at the solid-liquid interface by utilizing in-situ electrochemical scanning tunneling microscopy. Overall, the atomic-scale imaging of the reactive surfaces gives rise to the design rule of advanced bimetallic and mixed catalysts.

Speaker: Jeong Young Park, Korea Advanced Institute of Science and Technology

Room 3108