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Your search keyword '"Nam, Jong Seok"' showing total 15 results
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15 results on '"Nam, Jong Seok"'

1. Advancing Breathability of Respiratory Nanofilter by Optimizing Pore Structure and Alignment in Nanofiber Networks

Author

Bae, Jaehyeong, primary, Lee, Jiyoung, additional, Hwang, Won-Tae, additional, Youn, Doo-Young, additional, Song, Hyunsub, additional, Ahn, Jaewan, additional, Nam, Jong-Seok, additional, Jang, Ji-Soo, additional, Kim, Doo-won, additional, Jo, Woosung, additional, Kim, Taek-Soo, additional, Suk, Hyeon-Jeong, additional, Bae, Pan-Kee, additional, and Kim, Il-Doo, additional

Published
2023
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14. Cobalt-Doped Ceria Sensitizer Effects on Metal Oxide Nanofibers: Heightened Surface Reactivity for High-Performing Chemiresistive Sensors

Author

Baek, Jong Won, Han, Seunghee, Lee, Sang Eun, Ahn, Jaewan, Park, Chungseong, Nam, Jong Seok, Kim, Yoon Hwa, Shin, Euichul, Kim, Minhyun, Jang, Ji-Soo, Kim, Jihan, Park, Hee Jung, and Kim, Il-Doo

Abstract

Chemiresistive gas sensors based on semiconducting metal oxides typically rely on noble metal catalysts to enhance their sensitivity and selectivity. However, noble metal catalysts have several drawbacks for practical utilization, including their high cost, their propensity for spontaneous agglomeration, and poisoning effects with certain types of gases. As such, in the interest of commercializing the chemiresistive gas sensor technology, we propose an alternative design for a noble-metal-free sensing material through the case study of Co-doped ceria (Co–CeO2) catalysts embedded in a SnO2matrix. In this investigation, we utilized electrospinning and subsequent calcination to prepare Co–CeO2catalyst nanoparticles integrated with SnO2nanofibers (NFs) with uniform particle distribution and particle size regulation down to the sub-2 nm regime. The resulting Co–CeO2@SnO2NFs exhibited superior gas sensing characteristics toward isoprene (C5H8) gas, a significant biomarker for monitoring the onset of various diseases through breath diagnostics. In particular, we identified that the Co–CeO2catalysts, owing to the transition metal doping, facilitated the spillover of chemisorbed oxygen species to the SnO2sensing body. This resulting in the sensor having a 27.4-fold higher response toward 5 ppm of C5H8(compared to pristine SnO2), exceptionally high selectivity, and a low detection limit of 100 ppb. The sensor also exhibited high stability for prolonged response–recovery cycles, attesting to the strong anchoring of Co–CeO2catalysts in the SnO2matrix. Based on our findings, the transition metal-doped metal oxide catalysts, such as Co–CeO2, demonstrate strong potential to completely replace noble metal catalysts, thereby advancing the development of the commercially viable chemiresistive gas sensors free from noble metals, capable of detecting target gases at sub-ppm levels.

Published
2024
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15. Rapid Joule Heating Synthesis of Oxide-Socketed High-Entropy Alloy Nanoparticles as CO 2 Conversion Catalysts.

Author

Ahn J, Park S, Oh D, Lim Y, Nam JS, Kim J, Jung W, and Kim ID

Abstract

The unorthodox surface chemistry of high-entropy alloy nanoparticles (HEA-NPs), with numerous interelemental synergies, helps catalyze a variety of essential chemical processes, such as the conversion of CO 2 to CO, as a sustainable path to environmental remediation. However, the risk of agglomeration and phase separation in HEA-NPs during high-temperature operations are lasting issues that impede their practical viability. Herein, we present HEA-NP catalysts that are tightly sunk in an oxide overlayer for promoting the catalytic conversion of CO 2 with exceptional stability and performance. We demonstrated the controlled formation of conformal oxide overlayers on carbon nanofiber surfaces via a simple sol-gel method, which facilitated a large uptake of metal precursor ions and helped to decrease the reaction temperature required for nanoparticle formation. During the rapid thermal shock synthesis process, the oxide overlayer would also impede nanoparticle growth, resulting in uniformly distributed small HEA-NPs (2.37 ± 0.78 nm). Moreover, these HEA-NPs were firmly socketed in the reducible oxide overlayer, enabling an ultrastable catalytic performance involving >50% CO 2 conversion with >97% selectivity to CO for >300 h without extensive agglomeration. Altogether, we establish the rational design principles for the thermal shock synthesis of high-entropy alloy nanoparticles and offer a helpful mechanistic perspective on how the oxide overlayer impacts the nanoparticle synthesis behavior, providing a general platform for the designed synthesis of ultrastable and high-performance catalysts that could be utilized for various industrially and environmentally relevant chemical processes.

Published
2023
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