A study of surface oxides on Pt3Ni(111) and Pt3Co(111) using ambient pressure STM and XPS

Speaker

Bongjin Simon Mun

Affiliation

Gwangju Institute of Science and Technology

When
Place

Donostia International Physics Center (Hybrid Seminar)

Host

Ricardo Díez Muiño

Pt-transition metals alloys, e.g. Pt3Ni, Pt3Co, have shown excellent performance of oxygen reduction rate (ORR) in polymer exchange membrane fuel cell (PEMFC). While Pt3Ni alloy shows highest ORR, Pt3Co exhibits higher stability during electrochemical reaction. From early studies, the formation of a pure Pt “skin” layer was found on top surface layer during electrochemical reactions and the altered electronic structures of the Pt-skin layer was understood as the origin of the enhanced ORR at surface. Precise understanding on how the Pt-transition metals alloys behaves in response to the oxygen molecules during ORR is highly valuable information to design/engineer the advanced catalysts for future PEMFC. In this presentation, utilizing advanced in situ operando techniques, ambient pressure XPS and STM, the surface morphologies and chemical properties of Pt3Ni(111) and Pt3Co(111) under elevated oxygen pressure conditions will be discussed. In the case of the Pt3Ni, the subsurface Ni metal atoms segregate to surface under elevated oxygen pressure condition, followed by the formation of NiO(1−x) nano-clusters. On the other hand, under the similar condition, the Pt3Co surface shows the formation of Co oxides nano-island after the surface segregation of Co metal atoms . The formation and its roles of the NiO(1−x) nano-clusters and Co oxides during oxygen pressure will be carefully examined in details.


Zoom: https://dipc-org.zoom.us/j/99656076915
YouTube: https://youtube.com/live/U4rSlluib3w