Publications by authors named "Yong-Gun Shul"

16 Publications

  • Page 1 of 1

Transparent Bendable Secondary Zinc-Air Batteries by Controlled Void Ionic Separators.

Sci Rep 2019 Feb 28;9(1):3175. Epub 2019 Feb 28.

Department of Chemical and Biomolecular Engineering, Yonsei University, 262 Seongsanno, Seodaemun-gu, Seoul, 120-749, South Korea.

First ever transparent bendable secondary zinc-air batteries were fabricated. Transparent stainless-steel mesh was utilized as the current collector for the electrodes due to its reliable mechanical stability and electrical conductivity. After which separate methods were used to apply the active redox species. For the preparation of the anode, zinc was loaded by an electroplating process to the mesh. For the cathode, catalyst ink solution was spray coated with an airbrush for desired dimensions. An alkaline gel electrolyte layer was used for the electrolyte. Microscale domain control of the materials becomes a crucial factor for fabricating transparent batteries. As for the presented cell, anionic exchange polymer layer has been uniquely incorporated on to the cathode mesh as the separator which becomes a key procedure in the fabrication process for obtaining the desired optical properties of the battery. The ionic resin is applied in a fashion where controlled voids exist between the openings of the grid which facilitates light passage while guaranteeing electrical insulation between the electrodes. Further analysis correlates the electrode dimensions to the transparency of the system. Recorded average light transmittance is 48.8% in the visible light region and exhibited a maximum power density of 9.77 mW/cm. The produced battery shows both transparent and flexible properties while maintaining a stable discharge/charge operation.
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http://dx.doi.org/10.1038/s41598-019-38552-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6395654PMC
February 2019

Oxide-Carbon Nanofibrous Composite Support for a Highly Active and Stable Polymer Electrolyte Membrane Fuel-Cell Catalyst.

ACS Nano 2018 Jul 5;12(7):6819-6829. Epub 2018 Jul 5.

Department of Chemical and Biomolecular Engineering , Yonsei University , Yonsei-ro 50 , Seodaemun-gu, Seoul 03722 , Republic of Korea.

Well-designed electronic configurations and structural properties of electrocatalyst alter the activity, stability, and mass transport for enhanced catalytic reactions. We introduce a nanofibrous oxide-carbon composite by an in situ method of carbon nanofiber (CNF) growth by highly dispersed Ni nanoparticles that are exsoluted from a NiTiO surface. The nanofibrous feature has a 3D web structure with improved mass-transfer properties at the electrode. In addition, the design of the CNF/TiO support allows for complex properties for excellent stability and activity from the TiO oxide support and high electric conductivity through the connected CNF, respectively. Developed CNF/TiO-Pt nanofibrous catalyst displays exemplary oxygen-reduction reaction (ORR) activity with significant improvement of the electrochemical surface area. Moreover, exceptional resistance to carbon corrosion and Pt dissolution is proven by durability-test protocols based on the Department of Energy. These results are well-reflected to the single-cell tests with even-better performance at the kinetic zone compared to the commercial Pt/C under different operation conditions. CNF/TiO-Pt displays an enhanced active state due to the strong synergetic interactions, which decrease the Pt d-band vacancy by electron transfer from the oxide-carbon support. A distinct reaction mechanism is also proposed and eventually demonstrates a promising example of an ORR electrocatalyst design.
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http://dx.doi.org/10.1021/acsnano.8b02040DOI Listing
July 2018

Selective Ion Transporting Polymerized Ionic Liquid Membrane Separator for Enhancing Cycle Stability and Durability in Secondary Zinc-Air Battery Systems.

ACS Appl Mater Interfaces 2016 Oct 23;8(39):26298-26308. Epub 2016 Sep 23.

New Energy and Battery Engineering, Yonsei University , 134 Shinchon-dong, Seodaemoon-ku, Seoul 120-749, Republic of Korea.

Rechargeable secondary zinc-air batteries with superior cyclic stability were developed using commercial polypropylene (PP) membrane coated with polymerized ionic liquid as separators. The anionic exchange polymer was synthesized copolymerizing 1-[(4-ethenylphenyl)methyl]-3-butylimidazolium hydroxide (EBIH) and butyl methacrylate (BMA) monomers by free radical polymerization for both functionality and structural integrity. The ionic liquid induced copolymer was coated on a commercially available PP membrane (Celguard 5550). The coat allows anionic transfer through the separator and minimizes the migration of zincate ions to the cathode compartment, which reduces electrolyte conductivity and may deteriorate catalytic activity by the formation of zinc oxide on the surface of the catalyst layer. Energy dispersive X-ray spectroscopy (EDS) data revealed the copolymer-coated separator showed less zinc element in the cathode, indicating lower zinc crossover through the membrane. Ion coupled plasma optical emission spectroscopy (ICP-OES) analysis confirmed over 96% of zincate ion crossover was reduced. In our charge/discharge setup, the constructed cell with the ionic liquid induced copolymer casted separator exhibited drastically improved durability as the battery life increased more than 281% compared to the pure commercial PP membrane. Electrochemical impedance spectroscopy (EIS) during the cycle process elucidated the premature failure of cells due to the zinc crossover for the untreated cell and revealed a substantial importance must be placed in zincate control.
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http://dx.doi.org/10.1021/acsami.6b07841DOI Listing
October 2016

Synthesis and application of hexagonal perovskite BaNiO3 with quadrivalent nickel under atmospheric and low-temperature conditions.

Chem Commun (Camb) 2016 Sep 29;52(71):10731-4. Epub 2016 Jul 29.

Department of Chemical and Bio-molecular Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul, 120-749, Republic of Korea.

A hexagonal perovskite BaNiO3 with unusually high-valence nickel(iv) was synthesized under atmospheric and low-temperature conditions by an ethylenediamine-derived wet-chemical route. Secondary phases disappeared with increase in the pH value, and the single-phase BaNiO3 was successfully synthesized at pH 10. The specific surface area was ∼32 m(2) g(-1), which is significantly enhanced compared to the BaNiO3 (0.3 m(2) g(-1)) synthesized by flux-mediated crystal growth. The BaNiO3 was used as an oxygen-evolution reaction (OER) catalyst, and the specific mass activity was ∼5 times higher than that of the BaNiO3 synthesized by flux-mediated crystal growth. As a result, the ethylenediamine-derived sol-gel synthesis could be a simple technique to prepare crystalline compounds such as perovskites and spinels, with unusually high-valence transition metals.
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http://dx.doi.org/10.1039/c6cc05704gDOI Listing
September 2016

A New Family of Perovskite Catalysts for Oxygen-Evolution Reaction in Alkaline Media: BaNiO3 and BaNi(0.83)O(2.5).

J Am Chem Soc 2016 Mar 2;138(10):3541-7. Epub 2016 Mar 2.

Department of Chemical and Bio-molecular Engineering, Yonsei University , 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, Republic of Korea.

Establishment of a sustainable energy society has been strong driving force to develop cost-effective and highly active catalysts for energy conversion and storage devices such as metal-air batteries and electrochemical water splitting systems. This is because the oxygen evolution reaction (OER), a vital reaction for the operation, is substantially sluggish even with precious metals-based catalysts. Here, we show for the first time that a hexagonal perovskite, BaNiO3, can be a highly functional catalyst for OER in alkaline media. We demonstrate that the BaNiO3 performs OER activity at least an order of magnitude higher than an IrO2 catalyst. Using integrated density functional theory calculations and experimental validations, we unveil that the underlying mechanism originates from structural transformation from BaNiO3 to BaNi(0.83)O(2.5) (Ba6Ni5O15) over the OER cycling process.
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http://dx.doi.org/10.1021/jacs.6b00036DOI Listing
March 2016

Interface-designed Membranes with Shape-controlled Patterns for High-performance Polymer Electrolyte Membrane Fuel Cells.

Sci Rep 2015 Nov 10;5:16394. Epub 2015 Nov 10.

Department of Chemical and Biomolecular Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749, Korea.

Polymer electrolyte membrane fuel cell is a promising zero-emission power generator for stationary/automotive applications. However, key issues, such as performance and costs, are still remained for an economical commercialization. Here, we fabricated a high-performance membrane electrode assembly (MEA) using an interfacial design based on well-arrayed micro-patterned membranes including circles, squares and hexagons with different sizes, which are produced by a facile elastomeric mold method. The best MEA performance is achieved using patterned Nafion membrane with a circle 2 μm in size, which exhibited a very high power density of 1906 mW/cm(2) at 75 °C and Pt loading of 0.4 mg/cm(2) with 73% improvement compared to the commercial membrane. The improved performance are attributed to the decreased MEA resistances and increased surface area for higher Pt utilization of over 80%. From these enhanced properties, it is possible to operate at lower Pt loading of 0.2 mg/cm(2) with an outstanding performance of 1555 mW/cm(2) and even at air/low humidity operations.
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http://dx.doi.org/10.1038/srep16394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4639844PMC
November 2015

Tailoring gadolinium-doped ceria-based solid oxide fuel cells to achieve 2 W cm(-2) at 550 °C.

Nat Commun 2014 Jun 4;5:4045. Epub 2014 Jun 4.

Department of Chemical and Biomolecular Engineering, Yonsei University, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-749, Republic of Korea.

Low-temperature operation is necessary for next-generation solid oxide fuel cells due to the wide variety of their applications. However, significant increases in the fuel cell losses appear in the low-temperature solid oxide fuel cells, which reduce the cell performance. To overcome this problem, here we report Gd0.1Ce0.9O1.95-based low-temperature solid oxide fuel cells with nanocomposite anode functional layers, thin electrolytes and core/shell fibre-structured Ba0.5Sr0.5Co0.8Fe0.2O3-δ-Gd0.1Ce0.9O1.95 cathodes. In particular, the report describes the use of the advanced electrospinning and Pechini process in the preparation of the core/shell-fibre-structured cathodes. The fuel cells show a very high performance of 2 W cm(-2) at 550 °C in hydrogen, and are stable for 300 h even under the high current density of 1 A cm(-2). Hence, the results suggest that stable and high-performance solid oxide fuel cells at low temperatures can be achieved by modifying the microstructures of solid oxide fuel cell components.
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http://dx.doi.org/10.1038/ncomms5045DOI Listing
June 2014

Avatar DNA nanohybrid system in chip-on-a-phone.

Sci Rep 2014 May 14;4:4879. Epub 2014 May 14.

Center for Intelligent NanoBio Materials (CINBM), Department of Chemistry and Nano Science (Ewha Global Top 5 program-2011) and Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Republic of Korea.

Long admired for informational role and recognition function in multidisciplinary science, DNA nanohybrids have been emerging as ideal materials for molecular nanotechnology and genetic information code. Here, we designed an optical machine-readable DNA icon on microarray, Avatar DNA, for automatic identification and data capture such as Quick Response and ColorZip codes. Avatar icon is made of telepathic DNA-DNA hybrids inscribed on chips, which can be identified by camera of smartphone with application software. Information encoded in base-sequences can be accessed by connecting an off-line icon to an on-line web-server network to provide message, index, or URL from database library. Avatar DNA is then converged with nano-bio-info-cogno science: each building block stands for inorganic nanosheets, nucleotides, digits, and pixels. This convergence could address item-level identification that strengthens supply-chain security for drug counterfeits. It can, therefore, provide molecular-level vision through mobile network to coordinate and integrate data management channels for visual detection and recording.
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http://dx.doi.org/10.1038/srep04879DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4019957PMC
May 2014

Hollow fibers networked with perovskite nanoparticles for H2 production from heavy oil.

Sci Rep 2013 Oct 9;3:2902. Epub 2013 Oct 9.

1] Department of Chemical and Biomolecular Engineering, Yonsei University, Yonsei-ro 50, Seodaemun-gu, Seoul 120-749, Korea [2].

Design of catalytic materials has been highlighted to build ultraclean use of heavy oil including liquid-to-gas technology to directly convert heavy hydrocarbons into H2-rich gas fuels. If the H2 is produced from such heavy oil through high-active and durable catalysts in reforming process that is being constructed in hydrogen infrastructure, it will be addressed into renewable energy systems. Herein, the three different hollow fiber catalysts networked with perovskite nanoparticles, LaCr(0.8)Ru(0.2)O3, LaCr(0.8)Ru(0.1)Ni(0.1)O3, and LaCr(0.8)Ni(0.2)O3 were prepared by using activated carbon fiber as a sacrificial template for H2 production from heavy gas oil reforming. The most important findings were arrived at: (i) catalysts had hollow fibrous architectures with well-crystallized structures, (ii) hollow fibers had a high specific surface area with a particle size of ≈50 nm, and (iii) the Ru substituted ones showed high efficiency for H2 production with substantial durability under high concentrations of S, N, and aromatic compounds.
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http://dx.doi.org/10.1038/srep02902DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3793222PMC
October 2013

Fabrication of electrospun SiC fibers web/phenol resin composites for the application to high thermal conducting substrate.

J Nanosci Nanotechnol 2013 May;13(5):3307-12

Nano-IT Convergence Center, Korea Institute of Ceramic Engineering and Technology, 233-5 Gasan-dong Geumcheon-gu, 153-801 Seoul, Korea.

Polycabosilane (PCS) could be spun to form fiber web by electrospinning PCS solution in 30% dimethylformide (DMF)/toluene solvent at 25 kV. The electrospun web is stabilized at 200 degrees C for 1 hour to connect fibers by softening PCS webs and pyrolysed to synthesize silicon carbide (SiC) webs at 1800 degrees C. The pyrolysis at 1800 degrees C increased the SiC crystal size to 45 nm from 3 nm at 1300 degrees C. However, the pyrolysis at 1800 degrees C forms pores on the surface of SiC fibers due to oxygen evaporation generated during thermals curing. SiC/phenol composite webs could be fabricated by infiltration of phenol resin and hot pressing. The thermal conductivity measurement indicates that higher SiC fibers filler contents increase the thermal conductivity up to 1.9 W/mK for 40% fraction of filler contents from 0.5 W/mK for 20% fraction of filler.
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http://dx.doi.org/10.1166/jnn.2013.7264DOI Listing
May 2013

Pt nanoparticle-reduced graphene oxide nanohybrid for proton exchange membrane fuel cells.

J Nanosci Nanotechnol 2012 Jul;12(7):5669-72

Department of Chemical and Biomolecular Engineering, Yonsei University, Seoul 120-749, South Korea.

A platinum nanoparticle-reduced graphene oxide (Pt-RGO) nanohybrid for proton exchange membrane fuel cell (PEMFC) application was successfully prepared. The Pt nanoparticles (Pt NPs) were deposited onto chemically converted graphene nanosheets via ethylene glycol (EG) reduction. According to the powder X-ray diffraction (XRD) pattern and transmission electron microscopy (TEM) analysis, the face-centered cubic Pt NPs (3-5 nm in diameter) were homogeneously dispersed on the RGO nanosheets. The electrochemically active surface area and PEMFC power density of the Pt-RGO nanohybrid were determined to be 33.26 m2/g and 480 mW/cm2 (maximum values), respectively, at 75 degrees C and at a relative humidity (RH) of 100% in a single-cell test experiment.
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http://dx.doi.org/10.1166/jnn.2012.6350DOI Listing
July 2012

UV screening of ferulic acid-zinc basic salt nanohybrid with controlled release rate.

J Nanosci Nanotechnol 2011 Jan;11(1):413-6

Center for Intelligent NanoBio Materials (CINBM), Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.

Ferulic acid (FA), an organic UV absorber and free radical scavenger, was intercalated into an inorganic zinc basic salt (ZBS) matrix to prepare a UV screening material. FA molecules were vertically oriented bilayer in the ZBS lattice with an expansion of approximately 22.7 angstroms along the c-axis. The FA-ZBS nanohybrid exhibited a superior UV-A approximately UV-B screening ability and an antioxidant activity that was comparable to that of a pure FA molecule. The in vitro release test showed the biphasic release of the FA molecules from the FA-ZBS nanohybrid that consisted of an initial burst, followed by a slow and sustained release.
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http://dx.doi.org/10.1166/jnn.2011.3274DOI Listing
January 2011

Sepiocite, sepiolite-like nanoclay derived from hydrotalcite-like layered double hydroxide.

J Nanosci Nanotechnol 2011 Jan;11(1):382-5

Center for Intelligent NanoBio Materials (CINBM), Department of Bioinspired Science, Ewha Womans University, Seoul 120-750, Korea.

Sepiocite, a synthetic sepiolite-like nanoclay, was derived from hydrotalcite-like Mg2Al(CO3)0.5-layered double hydroxide (LDH) under phase transformation at 270 +/- 3 degrees C. The crystal structure of sepiocite is conceptually very similar to that of sepiolite derived from montmorillonite clay because sepiocite is formed through the alternation of the blocks and tunnels along the crystallographic c-axis, with a partial dehydroxylation of the octahedral Mg-(OH)-Al configuration into tetrahedral ones. Three important findings regarding sepiocite were arrived at: (i) its high specific surface area of 128.25 m2/g with an average particle size of 200 nm, which is approimately equal to 3.5 times larger than the specific surface area of the pristine LDH (34.21 m2/g); (ii) its non-swelling property; and (iii) its strongly reduced anion-exchange capacity.
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http://dx.doi.org/10.1166/jnn.2011.3239DOI Listing
January 2011

DNA [email protected] Shell.

J Am Chem Soc 2010 Dec 16;132(47):16735-6. Epub 2010 Sep 16.

Center for Intelligent NanoBio Materials (CINBM), Ewha Womans University, Seoul 120-750, Korea.

A chemically well-defined Bio [email protected] Shell nanohybrid, which consists of rationally designed DNA molecule core with a size of ∼100 nm and spherical inorganic nanoshell with an overall thickness of ∼10 nm reassembled with exfoliated layered metal hydroxide (MH nanosheets), is prepared. The DNA encapsulation and its release, due to the pH-dependent solubility of the MH nanoshell, plays a crucial role in maximizing the stability of base sequence-manipulated and probe-functionalized DNA molecules with designed information. The present DNA [email protected] Shell nanohybrid can provide wide bioinspired applications converged with nanotechnology, such as an advanced gene delivery system and a biomedical diagnostics, tracing/collection/sensing system for DNA-based information.
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http://dx.doi.org/10.1021/ja105809eDOI Listing
December 2010

[email protected] core-shell nanohybrid for efficient DNA retrieval.

J Nanosci Nanotechnol 2008 Oct;8(10):5014-7

Center for Intelligent Nano-Bio Materials (CINMB), Division of Nano Sciences BK21, Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.

Core-shell nanohybrid, [email protected], which consists of superparamagnetic Fe3O4 core and DNA attractive polypyrrole, was successfully synthesized through the free radical polymerization. The DNA retrieval efficacy of the nanohybrid was found to be very high in DNA solution with low concentration (approximately 33% uptake in 100 microM).
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http://dx.doi.org/10.1166/jnn.2008.1368DOI Listing
October 2008

Effect of metal and glycol on mechanochemical dechlorination of polychlorinated biphenyls (PCBs).

Chemosphere 2008 Aug 20;73(1):138-41. Epub 2008 Jun 20.

Center for Environment Technology Research, Korea Institute of Science and Technology, PO Box 131, Cheongryang, Seoul, Republic of Korea.

This paper assesses the potential of mechanochemical method with fine metal powder, glycol and alkali for polychlorinated biphenyls (PCBs) removal from waste insulating oil. The effects of relevant parameters, such as kinds of chemicals, rate and time of milling were examined. After each run, the total PCBs content in waste insulating oil was measured. Polyethylene glycol 200, long chain-glycol was more effective than triethylene glycol and ethylene glycol, short chain-glycol as hydrogen donor in mechanochemical dechlorination of PCBs. A maximum of 99.9% PCBs removal (below 2 ppm) and 94% total chlorine removal were achieved with the mechanochemical process for 2 h.
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http://dx.doi.org/10.1016/j.chemosphere.2008.04.051DOI Listing
August 2008
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