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제 목 : Surface reaction mechanism on metal/oxide interfaces of model catalysts uncovered with operando surface techniques
연 사 : 박정영 교수(KAIST)
일 시 : 2021년 5월 6일(목) 오후 4시 30분
* 실시간 온라인(Webex)으로 진행되는 세미나입니다.
<Webex참여>방번호: 170 974 2739링크: https://skku-ict.webex.com/meet/chem
Surface reaction mechanism on metal/oxide interfaces of model
catalysts uncovered with operando surface techniques
Jeong Young Park
Center for Nanomaterials and Chemical Reactions, Institute for Basic Science (IBS), Daejeon
305-701, South Korea
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST),
Daejeon 305-701, South Korea
The origin of the synergistic catalytic effect between metal catalysts and reducible
oxide has been debated for decades. Clarification of this effect, namely the strong metal–
support interaction (SMSI), requires an understanding of the geometric and electronic
structures of metal–metal oxide interfaces under operando conditions. A bimetallic Pt alloy
catalyst is an excellent platform to uncover the contentious role of the metal–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. In addition, mixed
catalysts that is composed of Pt nanoparticles supported on metal oxide supports have been
mainly utilized as the model catalysts for elucidation of SMSI effect.
In this talk, I present in-situ observation results of structural modulation on Pt-based
bimetal catalysts and mixed catalysts. We utilized PtNi, and PtCo that includes both of single
crystal and nanoparticle surfaces as model catalysts. Ambient-pressure scanning tunneling
microscopy and X-ray photoelectron spectroscopy measurements under CO oxidation
conditions show that the coexistence of Pt and metal oxide leads to the enhancement of catalytic
activity, indicating these metal-oxide interfaces provide more efficient reaction path for CO
oxidation. As a mixed catalysts, we prepared the model catalysts composed of Pt nanoparticles
and the mesoporous cobalt oxide that shows the enhancement of catalytic activity. Combining
other in-situ techniques including environmental transmission electron microscopy, hot
electron measurement, and in-situ diffuse reflectance FT-IR spectroscopy, we conclude that
the interface between Pt nanoparticles and oxide is the key factor that gives rise to SMSI effect.
Our results show that the presence of metal-oxide interfaces and the charge transfer through
the interface have significant implications in the surface reaction of heterogeneous catalysis.