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35 results on '"Chung, Min Wook"'

8. Identification of Single-Atom Ni Site Active toward Electrochemical CO2 Conversion to CO

Author

Kim, Haesol, primary, Shin, Dongyup, additional, Yang, Woojin, additional, Won, Da Hye, additional, Oh, Hyung-Suk, additional, Chung, Min Wook, additional, Jeong, Donghyuk, additional, Kim, Sun Hee, additional, Chae, Keun Hwa, additional, Ryu, Ji Yeon, additional, Lee, Junseong, additional, Cho, Sung June, additional, Seo, Jiwon, additional, Kim, Hyungjun, additional, and Choi, Chang Hyuck, additional

Published
2021
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16. Carbon Monoxide as a Promoter of Atomically Dispersed Platinum Catalyst in Electrochemical Hydrogen Evolution Reaction

Author

Kwon, Han Chang, primary, Kim, Minho, additional, Grote, Jan-Philipp, additional, Cho, Sung June, additional, Chung, Min Wook, additional, Kim, Haesol, additional, Won, Da Hye, additional, Zeradjanin, Aleksandar R., additional, Mayrhofer, Karl J. J., additional, Choi, Minkee, additional, Kim, Hyungjun, additional, and Choi, Chang Hyuck, additional

Published
2018
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17. Achilles' heel of Iron-Based Catalysts During Oxygen Reduction in Acidic Medium

Author

Choi, Chang Hyuck, primary, Lim, Hyung-Kyu, additional, Chon, Gajeon, additional, Chung, Min Wook, additional, Altin, Abdulrahman, additional, Sahraie, Nastaran Ranjbar, additional, Sougrati, Moulay-Tahar, additional, Stievano, Lorenzo, additional, Oh, Hyun Seok, additional, Park, Eun Soo, additional, Luo, Fang, additional, Strasser, Peter, additional, Drazic, Goran, additional, J. J. Mayrhofer, Karl, additional, Kim, Hyungjun, additional, and Jaouen, Frederic, additional

Published
2018
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19. The Achilles' heel of iron-based catalysts during oxygen reduction in an acidic medium

Author

Choi, Chang Hyuck, primary, Lim, Hyung-Kyu, additional, Chung, Min Wook, additional, Chon, Gajeon, additional, Ranjbar Sahraie, Nastaran, additional, Altin, Abdulrahman, additional, Sougrati, Moulay-Tahar, additional, Stievano, Lorenzo, additional, Oh, Hyun Seok, additional, Park, Eun Soo, additional, Luo, Fang, additional, Strasser, Peter, additional, Dražić, Goran, additional, Mayrhofer, Karl J. J., additional, Kim, Hyungjun, additional, and Jaouen, Frédéric, additional

Published
2018
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22. Electrochemical Evidence for Two Sub‐families of FeNxCy Moieties with Concentration‐Dependent Cyanide Poisoning.

Author

Chung, Min Wook, Chon, Gajeon, Kim, Hyungjun, Jaouen, Frédéric, and Choi, Chang Hyuck

Subjects
ELECTROCHEMISTRY, CYANIDE poisoning, FUEL cells, PLATINUM, NITROGEN, PHTHALOCYANINES
Abstract

Abstract: Iron‐nitrogen‐carbon (Fe−N−C) catalysts are one of the most promising family of materials for the successful replacement of noble Pt in low‐temperature fuel cells. Despite recent advances in the synthesis, activity, and site‐structure of Fe−N−C catalysts, further improved understanding of the nature of the Fe‐based active sites is still needed. In the present study, the existence of two sub‐families of FeNxCy moieties is revealed by the concentration dependence of cyanide poisoning on a Fe−N−C catalyst only comprising of atomically dispersed iron. The analysis of the activity decrease upon contact with various cyanide concentrations and activity recovery following rinsing with water reveals the presence of two sub‐groups of ORR‐active FeNxCy species. They are discriminated by the reversibility or irreversibility of the cyanide poisoning. From a Mössbauer spectroscopy study and poisoning test on a model compound, Fe(II) phthalocyanine (FePc), we hypothesize that the reversibility/irreversibility of cyanide poisoning is governed by the competitive adsorption of oxygen molecule and cyanide anion. It is proposed that FeNxCy moieties with Fe in low spin state reversibly adsorb cyanide, whereas those with a medium spin state irreversibly adsorb cyanide. [ABSTRACT FROM AUTHOR]

Published
2018
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29. Rational Design of a Hierarchical Tin Dendrite Electrode for Efficient Electrochemical Reduction of CO2.

Author

Won, Da Hye, Choi, Chang Hyuck, Chung, Jaehoon, Chung, Min Wook, Kim, Eun ‐ Hee, and Woo, Seong Ihl

Subjects
CATALYSIS synthesis, CARBON dioxide, CATALYSTS, ELECTRODES, FORMATES
Abstract

Catalysis is a key technology for the synthesis of renewable fuels through electrochemical reduction of CO2. However, successful CO2 reduction still suffers from the lack of affordable catalyst design and understanding the factors governing catalysis. Herein, we demonstrate that the CO2 conversion selectivity on Sn (or SnO x/Sn) electrodes is correlated to the native oxygen content at the subsurface. Electrochemical analyses show that the reduced Sn electrode with abundant oxygen species effectively stabilizes a CO2.− intermediate rather than the clean Sn surface, and consequently results in enhanced formate production in the CO2 reduction. Based on this design strategy, a hierarchical Sn dendrite electrode with high oxygen content, consisting of a multi-branched conifer-like structure with an enlarged surface area, was synthesized. The electrode exhibits a superior formate production rate (228.6 μmol h−1 cm−2) at −1.36 VRHE without any considerable catalytic degradation over 18 h of operation. [ABSTRACT FROM AUTHOR]

Published
2015
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34. Identification of Single-Atom Ni Site Active toward Electrochemical CO2Conversion to CO

Author

Kim, Haesol, Shin, Dongyup, Yang, Woojin, Won, Da Hye, Oh, Hyung-Suk, Chung, Min Wook, Jeong, Donghyuk, Kim, Sun Hee, Chae, Keun Hwa, Ryu, Ji Yeon, Lee, Junseong, Cho, Sung June, Seo, Jiwon, Kim, Hyungjun, and Choi, Chang Hyuck

Abstract

Electrocatalytic conversion of CO2into value-added products offers a new paradigm for a sustainable carbon economy. For active CO2electrolysis, the single-atom Ni catalyst has been proposed as promising from experiments, but an idealized Ni–N4site shows an unfavorable energetics from theory, leading to many debates on the chemical nature responsible for high activity. To resolve this conundrum, here we investigated CO2electrolysis of Ni sites with well-defined coordination, tetraphenylporphyrin (N4–TPP) and 21-oxatetraphenylporphyrin (N3O–TPP). Advanced spectroscopic and computational studies revealed that the broken ligand-field symmetry is the key for active CO2electrolysis, which subordinates an increase in the Ni redox potential yielding NiI. Along with their importance in activity, ligand-field symmetry and strength are directly related to the stability of the Ni center. This suggests the next quest for an activity–stability map in the domain of ligand-field strength, toward a rational ligand-field engineering of single-atom Ni catalysts for efficient CO2electrolysis.

Published
2021
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35. Identification of Single-Atom Ni Site Active toward Electrochemical CO 2 Conversion to CO.

Author

Kim H, Shin D, Yang W, Won DH, Oh HS, Chung MW, Jeong D, Kim SH, Chae KH, Ryu JY, Lee J, Cho SJ, Seo J, Kim H, and Choi CH

Abstract

Electrocatalytic conversion of CO 2 into value-added products offers a new paradigm for a sustainable carbon economy. For active CO 2 electrolysis, the single-atom Ni catalyst has been proposed as promising from experiments, but an idealized Ni-N 4 site shows an unfavorable energetics from theory, leading to many debates on the chemical nature responsible for high activity. To resolve this conundrum, here we investigated CO 2 electrolysis of Ni sites with well-defined coordination, tetraphenylporphyrin (N 4 -TPP) and 21-oxatetraphenylporphyrin (N 3 O-TPP). Advanced spectroscopic and computational studies revealed that the broken ligand-field symmetry is the key for active CO 2 electrolysis, which subordinates an increase in the Ni redox potential yielding Ni I . Along with their importance in activity, ligand-field symmetry and strength are directly related to the stability of the Ni center. This suggests the next quest for an activity-stability map in the domain of ligand-field strength, toward a rational ligand-field engineering of single-atom Ni catalysts for efficient CO 2 electrolysis.

Published
2021
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