|“Atomic scale tackling of greenhouse gas” highlighted by KAIST Compass
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|SCALE lab’s CO2 work has been highlighted by KAIST Compass
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Atomic scale tackling of greenhouse gas - KAIST Compass
SCALE lab’s CO2 work has been highlighted by KAIST Compass
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Atomic scale tackling of greenhouse gas
Sharply rising level of CO₂, a major greenhouse gas, have escalated a climate crisis that affects the living conditions of humankind, leading to the most uncertain natural environment on our planet since the agricultural revolution. A fundamental understanding of chemical processes of CO₂ on catalytic surfaces is of great importance for facile utilization and storage of CO₂. The research team led by Prof. Park observed the CO₂ dissociation process at the atomic level by using ambient pressure scanning tunneling microscopy. Furthermore, the selectivity of generation of CO₂ during the catalytic reaction was controlled by engineering metal-oxide interfaces and hot electron flux.
Utilization of carbon dioxide (CO₂) molecules has led to increased interest in the sustainable synthesis of methane or methanol. The representative reaction intermediate consisting of a carbonyl or formate group determines yields of the fuel source during catalytic reactions. However, the selective initial surface reaction processes have been assumed without a fundamental understanding at the molecular level. In collaboration with Professor Hyun You Kim from the Department of Materials Science and Engineering, Chungnam National University, and Prof. Bongjin Simon Mun at the Department of Physics, GIST, the research team at KAIST carried out in situ observations of spontaneous CO₂ dissociation over the model rhodium (Rh) catalyst at 0.1 mbar CO₂. The linear geometry of CO₂ gas molecules turns into a chemically active bent structure at the interface, which allows non-uniform charge transfer between chemisorbed CO₂ and surface Rh atoms. By combining scanning tunneling microscopy, X-ray photoelectron spectroscopy at near-ambient pressure, and computational calculations, the team revealed strong evidence for chemical bond cleavage of O‒CO* with ordered intermediate structure formation of (2 × 2)-CO on an atomically flat Rh(111) surface at room temperature  (Figure 1). These combined investigations provide fundamental insights for determining the selectivity of energy source production at the molecular level and therein contribute to the rational design of catalytic factors for improving CO₂ utilization. This study was published in Nature Communications in November 2020.
Another important way to control catalysts is via engineering metal-oxide interfaces, which are associated with energy dissipation and conversion processes during surface reactions, on a catalytic nanodiode. The architecture of these devices allows for quick extraction of hot electrons across metal–semiconductor interfaces before thermalization, thereby supplying key evidence of non-adiabatic charge transfer during surface reactions.
In collaboration with Professor Yousung Jung from the Department of Chemical and Biomolecular Engineering, and Prof. Yeon Sik Jung from the Department of Materials Science and Engineering, the research team at KAIST demonstrated a novel strategy to control the catalytic selectivity using hot electron flux on catalytic nanodiodes. The team showed that the selectivity toward the generation of CO₂ can be reduced during methanol oxidation by engineering metal-oxide interfaces. They observed the reaction-induced electronic excitation at the nanoscale metal-oxide interface, which was made possible by the real-time detection of hot electrons excited by the catalytic reaction in the newly designed Pt nanowires/TiO2 system (Figure 2). This technique for using the catalytic nanodiodes provides a powerful and highly sensitive tool for studying the processes of charge transfer at metal-oxide interfaces excited by surface chemical reactions. This study was published in Nature Communications in January 2021.
1. Jeongjin Kim, Hyunwoo Ha, Won Hui Doh, Kohei Ueda, Kazuhiko Mase, Hiroshi Kondoh, Bongjin Simon Mun*, Hyun You Kim* and Jeong Young Park*
How Rh surface breaks CO₂ molecules under ambient pressure
Nat. Comm 11, 5649 (2020) [https://www.nature.com/articles/s41467-020-19398-1]
2. Si Woo Lee, Jong Min Kim, Woonghyeon Park, Hyosun Lee, Gyu Rac Lee, Yousung Jung*, Yeon Sik Jung*, and Jeong Young Park*
Controlling hot electron flux and catalytic selectivity with nanoscale metal-oxide interfaces
Nat. Comm. 12, 40 (2021) [https://www.nature.com/articles/s41467-020-20293-y]
: Nature Communications