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Your search keyword '"Ryu, Jinseok"' showing total 11 results
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11 results on '"Ryu, Jinseok"'

4. Iridium-Cooperated, Symmetry-Broken Manganese Oxide Nanocatalyst for Water Oxidation

Author

Park, Sunghak, Jang, Taehwan, Choi, Seungwoo, Lee, Yoon Ho, Cho, Kang Hee, Lee, Moo Young, Seo, Hongmin, Lim, Hyung Kyu, Kim, Yujeong, Ryu, Jinseok, Im, Sang Won, Kim, Min Gyu, Park, Ji-Sang, Kim, Miyoung, Jin, Kyoungsuk, Kim, Sun Hee, Park, Gyeong-Su, Kim, Hyungjun, and Nam, Ki Tae

Abstract

The water oxidation reaction, the most important reaction for hydrogen production and other sustainable chemistry, is efficiently catalyzed by the Mn4CaO5cluster in biological photosystem II. However, synthetic Mn-based heterogeneous electrocatalysts exhibit inferior catalytic activity at neutral pH under mild conditions. Symmetry-broken Mn atoms and their cooperative mechanism through efficient oxidative charge accumulation in biological clusters are important lessons but synthesis strategies for heterogeneous electrocatalysts have not been successfully developed. Here, we report a crystallographically distorted Mn-oxide nanocatalyst, in which Ir atoms break the space group symmetry from I41/amdto P1. Tetrahedral Mn(II) in spinel is partially replaced by Ir, surprisingly resulting in an unprecedented crystal structure. We analyzed the distorted crystal structure of manganese oxide using TEM and investigated how the charge accumulation of Mn atoms is facilitated by the presence of a small amount of Ir.

Published
2023
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6. Atomic Reconstruction and Oxygen Evolution Reaction of Mn3O4 Nanoparticles

Author

Yoon, Sangmoon, primary, Seo, Hongmin, additional, Jin, Kyoungsuk, additional, Kim, Hyoung Gyun, additional, Lee, Seung-Yong, additional, Jo, Janghyun, additional, Cho, Kang Hee, additional, Ryu, Jinseok, additional, Yoon, Aram, additional, Kim, Young-Woon, additional, Zuo, Jian-Min, additional, Kwon, Young-Kyun, additional, Nam, Ki Tae, additional, and Kim, Miyoung, additional

Published
2022
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11. Atomic Reconstruction and Oxygen Evolution Reaction of Mn 3 O 4 Nanoparticles.

Author

Yoon S, Seo H, Jin K, Kim HG, Lee SY, Jo J, Cho KH, Ryu J, Yoon A, Kim YW, Zuo JM, Kwon YK, Nam KT, and Kim M

Abstract

Understanding the chemical states of individual surface atoms and their arrangements is essential for addressing several current issues such as catalysis, energy stroage/conversion, and environmental protection. Here, we exploit a profile imaging technique to understand the correlation between surface atomic structures and the oxygen evolution reaction (OER) in Mn 3 O 4 nanoparticles. We image surface structures of Mn 3 O 4 nanoparticles and observe surface reconstructions in the (110) and (101) planes. Mn 3+ ions at the surface, which are commonly considered as the active sites in OER, disappear from the reconstructed planes, whereas Mn 3+ ions are still exposed at the edges of nanoparticles. Our observations suggest that surface reconstructions can deactivate low-index surfaces of Mn oxides in OER. These structural and chemical observations are further validated by density functional theory calculations. This work shows why atomic-scale characterization of surface structures is crucial for a molecular-level understanding of a chemical reaction in oxide nanoparticles.

Published
2022
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