【学术报告】Dr. Ye Yifa（Lawrence Berkeley National Laboratory）

学 术 报 告

Revealing Carbon Dioxide Adsorption and Activation on Metal Catalysts by Ambient Pressure X-ray Photoelectron Spectroscopy

Dr. Ye Yifan

Lawrence Berkeley National Laboratory

    时间：2019年12月02日（一），09:30-12:00

地点：催化基础国家重点实验室三楼大会议室

报告摘要：

Converting carbon dioxide (CO₂) into liquid fuels and synthesis gas is a national priority. But there is no experimental information on the initial atomic level events for CO₂ reduction on the metal catalysts to provide the basis for developing improved catalysts. In order to provide this experimental information, we used ambient pressure X-ray photoelectron spectroscopy (APXPS) to examine the processes as metal catalyst surfaces exposed to CO₂ both alone and in the presence of H₂O at 298K, the results of which we correlated with quantum mechanics density to provide definitive interpretations.

We first investigated the interaction between CO₂ (+H₂O) with the Ag surface. On Ag we found very different gas adsorption and activation process compared to that on Cu. We found that physisorbed(l-) and chemisorbed (b-) CO₂ are not stable on pure Ag surface, but rather gaseous CO₂ reacts with absorbed O on Ag surface to form a chemisorbed surface species (O=CO₂^δ−). Adding H₂O and CO₂ then leads to up to four water attaching on (O=CO₂^δ−) and two water attaching onto b-CO₂ on the surface. We then also monitored the interaction between CO₂ (+H₂O) with the bimetallic AgCu surface and found a totally different adsorption and activation process compared to those on both Ag and Cu. We discovered how the chemistry and population of adsorbed species depends on the thermodynamics and surface kinetics of AgCu surface alloy. In particular, we find that adsorption of CO₂ and surface O induce subsurface Cu to migrate to the surface, modifying the stability and activation of CO₂ related chemisorbed species. Each metal surface modifies both the chemical speciation and the respective adsorption energies, thus providing a new basis for tuning CO₂ adsorption behavior to facilitate selective product formations.

报告人简介：

Yifan Ye got his bachelor degree of physical chemistry from University of Science and Technology of China at 2011. Then he got his PhD degree of Nuclear technology and science from University of Science and Technology of China at 2016 under the supervision of Prof. Junfa Zhu. During pursing for PhD degree, he visited Advanced Light Source, Lawrence Berkeley National Lab as a visit student from 2013 to 2016. After graduating, he continued his researches at Lawrence Berkeley National Lab as a joint postdoc in Advanced Light Source and Joint Center for Artificial Photosynthesis. 

He has a particular interest in studying the solid/gas, solid/liquid, and solid/solid interfaces of energy storage and conversion materials such as fuel cells, electrolyzers, catalysts, and batteries using in-situ soft and hard X-ray absorption/emission spectroscopy, and soft and tender Ambient Pressure X-ray Photoelectron Spectroscopy. Now, he has published more than 40 papers on peer-review journals, including Science, Nature Communication, JACS, etc.

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