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  1. Article ; Online: Enhanced Stability and Amplified Signal Output of Single-Wall Carbon Nanotube-Based NH 3 -Sensitive Electrode after Dual Plasma Treatment

    Joon Hyub Kim / Joon-Hyung Jin / Nam Ki Min

    Nanomaterials, Vol 10, Iss 1026, p

    2020  Volume 1026

    Abstract: Pristine nanomaterials are normally prepared using finely controlled fabrication processes. Because no imperfect nanostructure remains, they cannot be used directly as electrode substrates of functional devices. This is because perfectly organized ... ...

    Abstract Pristine nanomaterials are normally prepared using finely controlled fabrication processes. Because no imperfect nanostructure remains, they cannot be used directly as electrode substrates of functional devices. This is because perfectly organized nanostructures or nanomaterials commonly require posttreatment to generate intentionally, the kinds of desirable defects inside or on their surfaces that enable effective functionalization. Plasma treatment is an easier, simpler and more widely used way (relative to other methods) to modify a variety of nanomaterials, although plasma-functionalized nano surfaces commonly have a short lifetime. We present herein a dual plasma treatment (DPT) that significantly enhances the degree and lifetime of plasma-induced surface functional groups on single-walled carbon nanotubes (SWCNTs). The DPT process consists of two individually optimized oxygen–plasma treatments. The DPT-modified SWCNT functioned as a sensing material for ammonia gas for more than a month. It also provided more than three times the degree of functionality for amplified signal output than with a single-plasma-treated SWCNT electrode.
    Keywords dual plasma treatment ; oxygen plasma ; self-healing ; single-walled carbon nanotube ; surface functionalization ; Chemistry ; QD1-999
    Language English
    Publishing date 2020-05-01T00:00:00Z
    Publisher MDPI AG
    Document type Article ; Online
    Database BASE - Bielefeld Academic Search Engine (life sciences selection)

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  2. Article: Redox-Transition from Irreversible to Reversible Vitamin C by Pore Confinement in Microporous Carbon Network

    Choi, Sarah / Park, Anseong / Seo, Dongho / Lee, Won Bo / Nam, Ki Min / Kim, YongJoo / Chang, Jinho

    ACS applied materials & interfaces. 2022 Aug. 02, v. 14, no. 32

    2022  

    Abstract: Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical ... ...

    Abstract Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical reason for their exclusion as redox electrolytes in energy storage systems. In this article, we fully demonstrated that ascorbic acid (ASC), which is an abundant but redox-irreversible molecule, can become redox-reversible when it is confined in microporous carbon regimes. From a theoretical perspective, redox-reversibility in an electrochemical reaction coupled with an irreversible chemical process can be greatly enhanced due to kinetic acceleration toward the inverse direction of the chemical reaction by accumulation of products in the nanoconfined regime. However, the kinetic acceleration in a nanoconfined domain shows limitations for enhancing the redox-reversibility, which indicates that stabilization of the species undergoing an irreversible chemical process is another important factor for redox-reversibility enhancement. The origin of nanoporous confinement of ASC and its enhanced redox-reversibility was rationalized by molecular dynamics simulations. We found that ASC-clusters of a fully protonated ASC and its conjugated base formed inside carbon pores, which would be a main driving force for its confinement in microporous carbon networks. Lastly, we demonstrated a prototype energy storage device using redox-reversible ASC in microporous carbon as the half electrode, which shows the feasibility of ASC as a possible redox electrolyte in an aqueous energy storage system.
    Keywords ascorbic acid ; carbon ; chemical reactions ; electrochemistry ; electrodes ; electrolytes ; energy ; molecular dynamics ; nanopores ; porous media ; prototypes
    Language English
    Dates of publication 2022-0802
    Size p. 36557-36569.
    Publishing place American Chemical Society
    Document type Article
    ISSN 1944-8252
    DOI 10.1021/acsami.2c07719
    Database NAL-Catalogue (AGRICOLA)

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  3. Article ; Online: Unlocking the Potential of Bi

    Ma, Ahyeon / Lee, Yongsoon / Seo, Dongho / Kim, Jiyoon / Park, Soohyeok / Son, Jihoon / Kwon, Woosuck / Nam, Dae-Hyun / Lee, Hyosung / Kim, Yong-Il / Um, Han-Don / Shin, Hyeyoung / Nam, Ki Min

    Advanced science (Weinheim, Baden-Wurttemberg, Germany)

    2024  , Page(s) e2400874

    Abstract: Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical ... ...

    Abstract Various electrocatalysts are extensively examined for their ability to selectively produce desired products by electrochemical CO
    Language English
    Publishing date 2024-05-17
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2808093-2
    ISSN 2198-3844 ; 2198-3844
    ISSN (online) 2198-3844
    ISSN 2198-3844
    DOI 10.1002/advs.202400874
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Heterointerface Effect on Two-Step Nucleation Mechanism of Bi Particles.

    Kim, Hyung Joong / Kim, Jong Hoon / Jeong, Jong Seok / Moon, Chang Youn / Nahm, Sahn / Nam, Ki Min / Park, Jucheol / Kim, Young Heon

    Nano letters

    2022  Volume 22, Issue 8, Page(s) 3252–3259

    Abstract: The nucleation and crystallization of Bi particles on two matrices, crystalline bismuth sulfide ( ...

    Abstract The nucleation and crystallization of Bi particles on two matrices, crystalline bismuth sulfide (
    Language English
    Publishing date 2022-04-18
    Publishing country United States
    Document type Journal Article
    ISSN 1530-6992
    ISSN (online) 1530-6992
    DOI 10.1021/acs.nanolett.1c04966
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Redox-Transition from Irreversible to Reversible Vitamin C by Pore Confinement in Microporous Carbon Network.

    Choi, Sarah / Park, Anseong / Seo, Dongho / Lee, Won Bo / Nam, Ki Min / Kim, YongJoo / Chang, Jinho

    ACS applied materials & interfaces

    2022  Volume 14, Issue 32, Page(s) 36557–36569

    Abstract: Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical ... ...

    Abstract Enhancement of redox-reversibility in electroactive species has been studied because of fundamental interest and their importance for energy storage systems. Various electroactive molecules suffer from redox-irreversible behavior, and this is a critical reason for their exclusion as redox electrolytes in energy storage systems. In this article, we fully demonstrated that ascorbic acid (ASC), which is an abundant but redox-irreversible molecule, can become redox-reversible when it is confined in microporous carbon regimes. From a theoretical perspective, redox-reversibility in an electrochemical reaction coupled with an irreversible chemical process can be greatly enhanced due to kinetic acceleration toward the inverse direction of the chemical reaction by accumulation of products in the nanoconfined regime. However, the kinetic acceleration in a nanoconfined domain shows limitations for enhancing the redox-reversibility, which indicates that stabilization of the species undergoing an irreversible chemical process is another important factor for redox-reversibility enhancement. The origin of nanoporous confinement of ASC and its enhanced redox-reversibility was rationalized by molecular dynamics simulations. We found that ASC-clusters of a fully protonated ASC and its conjugated base formed inside carbon pores, which would be a main driving force for its confinement in microporous carbon networks. Lastly, we demonstrated a prototype energy storage device using redox-reversible ASC in microporous carbon as the half electrode, which shows the feasibility of ASC as a possible redox electrolyte in an aqueous energy storage system.
    Language English
    Publishing date 2022-08-02
    Publishing country United States
    Document type Journal Article
    ISSN 1944-8252
    ISSN (online) 1944-8252
    DOI 10.1021/acsami.2c07719
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: Unraveling the Simultaneous Enhancement of Selectivity and Durability on Single-Crystalline Gold Particles for Electrochemical CO

    Lim, Yun Ji / Seo, Dongho / Abbas, Syed Asad / Jung, Haeun / Ma, Ahyeon / Lee, Kug-Seung / Lee, Gaehang / Lee, Hosik / Nam, Ki Min

    Advanced science (Weinheim, Baden-Wurttemberg, Germany)

    2022  Volume 9, Issue 20, Page(s) e2201491

    Abstract: Electrochemical carbon dioxide reduction is a mild and eco-friendly approach for ... ...

    Abstract Electrochemical carbon dioxide reduction is a mild and eco-friendly approach for CO
    Language English
    Publishing date 2022-05-02
    Publishing country Germany
    Document type Journal Article
    ZDB-ID 2808093-2
    ISSN 2198-3844 ; 2198-3844
    ISSN (online) 2198-3844
    ISSN 2198-3844
    DOI 10.1002/advs.202201491
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  7. Article: Heteroatom-doped nanomaterials/core–shell nanostructure based electrocatalysts for the oxygen reduction reaction

    Nagappan, Saravanan / Duraivel, Malarkodi / Hira, Shamim Ahmed / Prabakar, Kandasamy / Ha, Chang-Sik / Joo, Sang Hoon / Nam, Ki Min / Park, Kang Hyun

    Journal of materials chemistry A. 2022 Jan. 18, v. 10, no. 3

    2022  

    Abstract: Recently, heteroatom doped core–shell nanostructures (HCSNs) have been widely used as superior electrocatalysts for the oxygen reduction reaction (ORR) owing to their enhanced ORR performance and stability under harsh environmental conditions. In this ... ...

    Abstract Recently, heteroatom doped core–shell nanostructures (HCSNs) have been widely used as superior electrocatalysts for the oxygen reduction reaction (ORR) owing to their enhanced ORR performance and stability under harsh environmental conditions. In this review, we provide the importance of HCSNs and explain how the ORR performance can be enhanced by various heteroatom dopants, such as nitrogen, sulfur, phosphorous, boron, and combinations of two or more heteroatoms. Various types of nitrogen doping were performed with different forms of nitrogen-containing organic compounds in CSNs, such as metal–organic frameworks, zeolitic imidazolate frameworks, and transition metals containing nitrogen sources, which have been used widely for the ORR because they form a high surface area, a facet surface structure, and reactive active sites in the presence of elements that are useful for the ORR catalytic activity. Furthermore, we briefly discuss the synthesis and fabrication of highly efficient ORR electrodes using a combination of di-, tri-, or multi-heteroatom-doped CSNs. Finally, we discuss the superior ORR activities of the HCSNs reported in recent literature and compare the activity with various reactive descriptors and the broad scope of these HCSNs for practical applications, along with their drawbacks and future demands.
    Keywords boron ; catalytic activity ; electrochemistry ; nitrogen ; phosphorus ; sulfur ; surface area
    Language English
    Dates of publication 2022-0118
    Size p. 987-1021.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 2702232-8
    ISSN 2050-7496 ; 2050-7488
    ISSN (online) 2050-7496
    ISSN 2050-7488
    DOI 10.1039/d1ta09861f
    Database NAL-Catalogue (AGRICOLA)

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  8. Article: Chemical and electrochemical synthesis of cobalt hydroxides: selective phase transformation and application to distinct electrocatalytic reactions [Erratum: June 2022, v.10(26); p.12748]

    Park, Joon Yong / Kim, Ha Young / Kim, Yong-Il / Jo, So Yeong / Abbas, Syed Asad / Seo, Dongho / Ma, Ahyeon / Nam, Ki Min

    Journal of materials chemistry A. 2022 June 7, v. 10, no. 22

    2022  

    Abstract: Individual cobalt hydroxides with clearly identified crystal structures can aid in discerning the relationship between the crystal structure and catalytic activity. Herein, the crystal structure of α-Co(OH)₂ and its transformations to other cobalt ... ...

    Abstract Individual cobalt hydroxides with clearly identified crystal structures can aid in discerning the relationship between the crystal structure and catalytic activity. Herein, the crystal structure of α-Co(OH)₂ and its transformations to other cobalt hydroxides are fully investigated. The α-Co(OH)₂ structure comprised a layered structure with anion intercalation, [Coᴼʰ₀.₇₇Coᵀᵈ₀.₂₃(OH)₁.₇₇]⁰.²³⁺[Cl₀.₂₃·0.64H₂O], which was identified by Rietveld refinement analysis using X-ray diffraction. Phase transformations of metastable α-Co(OH)₂ into various other cobalt hydroxides, such as β-Co(OH)₂, γ-CoOOH, and β-CoOOH, were selectively performed through a variation in the chemical environment, and their structures were fully characterized. In addition, electrochemical oxidative transformations of α-Co(OH)₂ and β-Co(OH)₂ into γ-CoOOH and β-CoOOH, respectively, were successfully accomplished. The prepared cobalt hydroxides were applied to the oxygen evolution reaction (OER) and chloride oxidation reaction (COR) to investigate the correlation between the crystal structure and activity. The γ-CoOOH showed better OER catalytic activity than β-CoOOH. In contrast, β-CoOOH showed higher COR selectivity than γ-CoOOH. Interestingly, the faradaic efficiency of the COR was over 97% on β-CoOOH at a concentration of 0.1 M NaCl, and this value is the highest COR faradaic efficiency compared to all other electrodes. The importance of the crystal structure for each electrocatalytic reaction is elucidated.
    Keywords X-ray diffraction ; catalytic activity ; cobalt ; crystal structure ; electrochemistry ; electrosynthesis ; oxidation ; oxygen production ; phase transition
    Language English
    Dates of publication 2022-0607
    Size p. 12047-12054.
    Publishing place The Royal Society of Chemistry
    Document type Article
    ZDB-ID 2702232-8
    ISSN 2050-7496 ; 2050-7488
    ISSN (online) 2050-7496
    ISSN 2050-7488
    DOI 10.1039/d2ta02166h
    Database NAL-Catalogue (AGRICOLA)

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  9. Article ; Online: Chemical approach to a new crystal structure: phase control of manganese oxide on a carbon sphere template.

    Nam, Ki Min / Park, Joon T

    Chemistry, an Asian journal

    2014  Volume 9, Issue 12, Page(s) 3525–3532

    Abstract: The stabilization and growth of a non-native structure, hexagonal wurtzite MnO (h-MnO), is explored via kinetic control of manganese precursor on a carbon sphere template. MnO is most stable in the cubic rock-salt structure (c-MnO), and a number of ... ...

    Abstract The stabilization and growth of a non-native structure, hexagonal wurtzite MnO (h-MnO), is explored via kinetic control of manganese precursor on a carbon sphere template. MnO is most stable in the cubic rock-salt structure (c-MnO), and a number of studies have focused on the synthesis and properties of this rock-salt phase. However, h-MnO has not been fully characterized before our work. Prolonged heating at a relatively low temperature yields c-MnO, whereas rapid heating of the reaction mixture at reflux produces h-MnO in the presence of carbon spheres. The effect of benzyl amine concentration on the formation of two different oxidation states (c-MnO and t-Mn3O4) was examined as well. Moreover, the structural stability of the manganese oxides and phase transition of MnO in terms of the wurtzite to rock-salt structural transformation have been investigated.
    Language English
    Publishing date 2014-12
    Publishing country Germany
    Document type Journal Article
    ISSN 1861-471X
    ISSN (online) 1861-471X
    DOI 10.1002/asia.201403021
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  10. Article: Current research on single-entity electrochemistry for soft nanoparticle detection: Introduction to detection methods and applications

    Nguyen, Thu Ha T / Lee, Jungeun / Kim, Hae-Young / Nam, Ki Min / Kim, Byung-Kwon

    Biosensors & bioelectronics. 2020 Mar. 01, v. 151

    2020  

    Abstract: In recent years, rapid progress in the field of single-entity electrochemistry (SEE) has opened a novel exploratory area in the field of analytical and electrochemistry. SEE is a method of studying the behavior of particles at the single particle level, ... ...

    Abstract In recent years, rapid progress in the field of single-entity electrochemistry (SEE) has opened a novel exploratory area in the field of analytical and electrochemistry. SEE is a method of studying the behavior of particles at the single particle level, which yields important information on the diffusion coefficient, individual particle size, size distribution, catalytic activity, collision frequency, and internal substances of the particles. Various types of particles have been studied through SEE. Among them, this review focuses on the results of analyzing soft particles (cells, proteins, viruses, liposomes, enzymes, vesicles, emulsion droplets, micelles, carbonaceous nanomaterials, and others). We introduce the various electrochemical techniques used in SEE and discuss important concepts and equations that must be known to apply SEE. We also introduce the results of recent research on several important soft particles. Finally, the potential applications in areas such as sensors, materials, catalysts, energy, and biomedicine, as well as the trends of related works are described. In the future, research on soft particle analysis using SEE is expected to increase rapidly, and this review is expected to be a valuable reference for researchers in the field.
    Keywords biosensors ; catalysts ; catalytic activity ; diffusivity ; droplets ; electrochemistry ; emulsions ; energy ; enzymes ; equations ; medicine ; micelles ; nanoparticles ; particle size ; proteins ; viruses
    Language English
    Dates of publication 2020-0301
    Publishing place Elsevier B.V.
    Document type Article
    ZDB-ID 1011023-9
    ISSN 1873-4235 ; 0956-5663
    ISSN (online) 1873-4235
    ISSN 0956-5663
    DOI 10.1016/j.bios.2019.111999
    Database NAL-Catalogue (AGRICOLA)

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