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Materials Frontier No.189

Title: Maging of Atomic Interplays at the Interfaces in Catalysts
Speaker: Wenpei Gao Dr, University of California-Irvine
Date/Time: 2017-6-9, 10:00am
Venue: 308, XU Zuyao Building
Inviter:Prof.WU Jianbo
Dr. Wenpei Gao is currently a postdoctoral research fellow in Prof. Xiaoqing Pan’s group at the University of California, Irvine. His current focus is on the study on catalyst dynamics using advanced electron microscopy techniques. He graduated from Peking University in 2010 with bachelor degree in physics. From 2010 to 2015, he took his Ph.D study in Prof. Jian-Min Zuo’s group at the University of Illinois at Urbana-Champaign, with a focus on developing ex situ and in situ electron microscopy instruments and technologies. He visited Oak Ridge National Laboratory from 2015 to 2016 to work with Dr. Miaofang Chi on the in situ study of nanoparticle kinetics using liquid/gas cells. He has been awarded multiple awards including Racheff-Intel Award for his excellence in graduate study(2015), and Eric Samuel Award from the Microscopy Society of America (2012).
Developing novel catalysts with high efficiency and selectivity is critical for enabling future clean energy conversion technologies. In catalysts, the interfaces have long been considered the most critical factor in controlling the reaction mechanisms. These interfaces include the gas-solid, liquid-solid interfaces on catalyst surface, and the interfaces within the heterogeneous catalyst. Tuning interfaces in catalyst systems is an important strategy in the design of novel catalysts.  However, the governing principle of how interfaces contribute to catalyst behavior, especially in terms of interactions with intermediates and their stability during electrochemical operation, are largely unknown. This is mainly due to the evolving nature of such interfaces. These interfacial arrangements evolve continuously during synthesis, processing, use, and even during static operation. Small changes in the structural and chemical configuration of these interfaces may result in altering the catalytic performance.
Now advanced scanning/transmission electron microscopy (S/TEM) can be used as an efficient probe to tackle the local atomic and electronic structures at the interfaces with high precision while in situ monitoring the dynamic behavior. The information such as the lattice strain and surface elemental distribution, the 3D atomic structure and catalyst dynamics can greatly benefit catalytic research. In this talk, we will discuss on the new findings on interface structures of supported Au nanoparticles, on the dynamics of shaped Pt nanoparticles in different environments, and on the new possibilities provided by advanced electron microscopy in the study on extended catalyst interfacial structures, including those interfaces between particle and support, between core and shell, between separate phases and twinned grains, and between the catalyst surface and gas/liquid. When combined with theoretical modelling, the insights are key to understand the activity, selectivity, stability and overall performance of precious metal-based heterogeneous catalysts.

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