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The lacking of laboratory black carbon (BC) samples have long challenged the corresponding toxicological research; furthermore, the toxicity tests of engineered carbon nanoparticles were unable to reflect atmospheric BC. As a simplified approach, we have synthesized artificial BC (aBC) for the purpose of representing atmospheric BC. Surface chemical properties of aBC were controlled by thermal treatment, without transforming its physical characteristics; thus, we were able to examine the toxicological effects on A549 human lung cells arising from aBC with varying oxidation surface properties. X-ray photoelectron spectroscopy, as well as Raman and Fourier transform infrared spectroscopy, verified the presence of increased amounts of oxygenated functional groups on the surface of thermally-treated aBC, indicating aBC oxidization at elevated temperatures; aBC with increased oxygen functional group content displayed increased toxicity to A549 cells, specifically by decreasing cell viability to 45% and elevating reactive oxygen species levels up to 294% for samples treated at 800 °C.
Yen Le; Jong-Sang Youn; Hi-Gyu Moon; Xin-Yu Chen; Dong-Im Kim; Hyun-Wook Cho; Kyu-Hong Lee; Ki-Joon Jeon. Relationship between Cytotoxicity and Surface Oxidation of Artificial Black Carbon. Nanomaterials 2021, 11, 1455 .
AMA StyleYen Le, Jong-Sang Youn, Hi-Gyu Moon, Xin-Yu Chen, Dong-Im Kim, Hyun-Wook Cho, Kyu-Hong Lee, Ki-Joon Jeon. Relationship between Cytotoxicity and Surface Oxidation of Artificial Black Carbon. Nanomaterials. 2021; 11 (6):1455.
Chicago/Turabian StyleYen Le; Jong-Sang Youn; Hi-Gyu Moon; Xin-Yu Chen; Dong-Im Kim; Hyun-Wook Cho; Kyu-Hong Lee; Ki-Joon Jeon. 2021. "Relationship between Cytotoxicity and Surface Oxidation of Artificial Black Carbon." Nanomaterials 11, no. 6: 1455.
A simple, inexpensive, and scalable method for transforming phosphorous pentoxide (P2O5) into black phosphorus (BP)-based composites was developed. The BP-based composites of [email protected], [email protected]2O3, and [email protected]2 synthesized by a one-pot mechanochemical reduction of P2O5 using Mg, Al, or Ti were composed of nanocrystalline BP within the metal oxide matrices of MgO, Al2O3, or TiO2, respectively. Subsequently, the potential of these composites as anode materials in rechargeable Li-ion batteries (LIBs) was investigated. [email protected]2 showed the highest electrochemical performance among the BP-based composites. Specifically, the [email protected]2 exhibited a high reversible capacity over 510 mAh g−1 after 300 cycles and a fast rate capability of ~ 400 mAh g−1 at the 3C rate. The superior electrochemical performance of [email protected]2 was attributed to the well-dispersed nanocrystalline BP and the Li-reactive TiO2 matrix. Additionally, the formation of LixTiO2 in the Li-reactive TiO2 matrix during Li cycling increased the electrochemical Li-ion conductivity and diffusivity, contributing to the enhanced electrochemical performance. Therefore, the [email protected]2 synthesized by the one-pot mechanochemical reduction has high potential as a superior LIB anode.
Tae-Hyun Kim; Ki-Joon Jeon; Cheol-Min Park. Black [email protected] (M = Mg, Al, or Ti) composites as superior Li-ion battery anodes. Chemical Engineering Journal 2021, 424, 130366 .
AMA StyleTae-Hyun Kim, Ki-Joon Jeon, Cheol-Min Park. Black [email protected] (M = Mg, Al, or Ti) composites as superior Li-ion battery anodes. Chemical Engineering Journal. 2021; 424 ():130366.
Chicago/Turabian StyleTae-Hyun Kim; Ki-Joon Jeon; Cheol-Min Park. 2021. "Black [email protected] (M = Mg, Al, or Ti) composites as superior Li-ion battery anodes." Chemical Engineering Journal 424, no. : 130366.
In this study, we examined tire and road wear microparticles (TRWMPs) in road dust along the Seoul metropolitan area, from industrial and residential areas. The road dust samples were collected via vacuum sweep methods and then filtered to obtain particles with diameters less than 75 μm. To quantify the TRWMPs in road dust, we used the raw materials of tire components, natural rubber (NR), and styrene–butadiene rubber (SBR), as standard materials. We evaluated the usability of the pyrolyzer-gas chromatography/mass spectrometry py-GC/MS method introduced in ISO/TS 20593 by confirming the decomposition temperatures of the NR and SBR by thermogravimetric (TG) and evolved gas analysis (EGA)-MS. The average of TRWMPs in industrial and residential area road dust were 22,581 and 9818 μg/g, respectively, indicating that the industrial area has 2.5 times higher TRWMPs concentration. Further, the NR, the main component of truck bus radial, to SBR, the main component of passenger car radial, ratio was slightly higher in the industrial area than in the residential area. This presumably means that the high traffic volume, including heavy duty vehicles in industrial areas, affected the higher concentration of TRWMPs. This study reveals the growing evidence of the importance of TRWMPs in road dust and how TRWMPs quantity can impact the air quality of the Seoul metropolitan area.
Jong-Sang Youn; Young-Min Kim; Muhammad Zain Siddiqui; Atsushi Watanabe; Sehyun Han; Sangmin Jeong; Yong-Won Jung; Ki-Joon Jeon. Quantification of tire wear particles in road dust from industrial and residential areas in Seoul, Korea. Science of The Total Environment 2021, 784, 147177 .
AMA StyleJong-Sang Youn, Young-Min Kim, Muhammad Zain Siddiqui, Atsushi Watanabe, Sehyun Han, Sangmin Jeong, Yong-Won Jung, Ki-Joon Jeon. Quantification of tire wear particles in road dust from industrial and residential areas in Seoul, Korea. Science of The Total Environment. 2021; 784 ():147177.
Chicago/Turabian StyleJong-Sang Youn; Young-Min Kim; Muhammad Zain Siddiqui; Atsushi Watanabe; Sehyun Han; Sangmin Jeong; Yong-Won Jung; Ki-Joon Jeon. 2021. "Quantification of tire wear particles in road dust from industrial and residential areas in Seoul, Korea." Science of The Total Environment 784, no. : 147177.
This study examines environmental impact assessment considering filterable particulate matter (FPM) and condensable particulate matter (CPM) to improve the accuracy of the air quality model. Air pollutants and meteorological data were acquired from Korea’s national monitoring station near a residential development area in the target district and background site. Seasonal emissions of PM2.5, including CPM, were estimated using the California puff (CALPUFF) model, based on Korea’s national emissions inventory. These results were compared with the traditional environmental impact assessment results. For the residential development area, the seasonal PM2.5 concentration was predicted by considering FPM and CPM emissions in the target area as well as the surrounding areas. In winter and spring, air quality standards were not breached because only FPM was considered. However, when CPM was included in the analysis, the results exceeded the air quality standards. Furthermore, it was predicted that air quality standards would not be breached in summer and autumn, even when CPM is included. In other words, conducting an environmental impact assessment on air pollution including CPM affects the final environmental decision. Therefore, it is concluded that PM2.5 should include CPM for greater accuracy of the CALPUFF model for environmental impact assessment.
Doo Choi; Jong-Sang Youn; Im Lee; Byung Choi; Ki-Joon Jeon. Considering Condensable Particulate Matter Emissions Improves the Accuracy of Air Quality Modeling for Environmental Impact Assessment. Sustainability 2021, 13, 4470 .
AMA StyleDoo Choi, Jong-Sang Youn, Im Lee, Byung Choi, Ki-Joon Jeon. Considering Condensable Particulate Matter Emissions Improves the Accuracy of Air Quality Modeling for Environmental Impact Assessment. Sustainability. 2021; 13 (8):4470.
Chicago/Turabian StyleDoo Choi; Jong-Sang Youn; Im Lee; Byung Choi; Ki-Joon Jeon. 2021. "Considering Condensable Particulate Matter Emissions Improves the Accuracy of Air Quality Modeling for Environmental Impact Assessment." Sustainability 13, no. 8: 4470.
Two-dimensional quantum dots (2D QDs) comprising PtS2 with low Pt loading (0.002 wt.%) distributed on a distinctive CVD-grown titanium carbide substrate (PtS2/TiC) was successfully synthesized and employed for a hydrogen evolution reaction (HER). Notably, despite the low loading of the former component, PtS2/TiC showed excellent HER activity with a superior overpotential (55 mV at 10 mA/cm−2) to that of commercial Pt/C (50 mV at 10 mA/cm−2). The Faraday efficiency of PtS2/TiC was found to be 92.5 %, revealing the superior properties of hydrogen production. The In-situ Raman spectra reveal the important role of S atoms in PtS2 as the active sites for HER, as evidenced by SH bonding formation at 2532 cm-1 during the HER process. This study provides a fundamental understanding essential for the design of more efficient catalysts in the field of electrochemical applications.
Sangmin Jeong; Hien Duy Mai; Tri Khoa Nguyen; Jong-Sang Youn; Ki-Hun Nam; Cheol-Min Park; Ki-Joon Jeon. Atomic interactions of two-dimensional PtS2 quantum dots/TiC heterostructures for hydrogen evolution reaction. Applied Catalysis B: Environmental 2021, 293, 120227 .
AMA StyleSangmin Jeong, Hien Duy Mai, Tri Khoa Nguyen, Jong-Sang Youn, Ki-Hun Nam, Cheol-Min Park, Ki-Joon Jeon. Atomic interactions of two-dimensional PtS2 quantum dots/TiC heterostructures for hydrogen evolution reaction. Applied Catalysis B: Environmental. 2021; 293 ():120227.
Chicago/Turabian StyleSangmin Jeong; Hien Duy Mai; Tri Khoa Nguyen; Jong-Sang Youn; Ki-Hun Nam; Cheol-Min Park; Ki-Joon Jeon. 2021. "Atomic interactions of two-dimensional PtS2 quantum dots/TiC heterostructures for hydrogen evolution reaction." Applied Catalysis B: Environmental 293, no. : 120227.
Carbon black (CB) is an inexpensive and widely used carbonaceous material. However, the reversibility between CB and Li or Na is very poor, and the initial coulombic efficiency (ICE) is so low that it cannot be used as an electrode material for rechargeable batteries. In this study, we successfully designed superior CB as a high-performance conducting additive for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) using a simple two-step strategy: amorphization and pre-lithiation/sodiation. The Li- and Na-reversible capacities of amorphized CB increased significantly from 213 to 564 mAh g−1 for LIB and from 92 to 209 mAh g−1 for NIB; however, the corresponding ICEs of 61.5% for LIB and 33.5% for NIB are poor. The poor ICEs are supplemented via pre-lithiation/sodiation in the amorphized CB, which show over 100% ICEs with high Li- and Na-reversible capacities. Specifically, the modified CB has highly reversible capacities (>500 mAh g−1 for LIB, >300 mAh g−1 for NIB) with exceptionally high ICEs (133% ICE for LIB, 160% ICE for NIB), stable reversible capacities for over 100 cycles (470 mAh g−1 for LIB, 278 mAh g−1 for NIB), fast rate capabilities with highly reversible capacities at a 3C rate (~330 mAh g−1 for LIB, ~190 mAh g−1 for NIB), and excellent cycling behavior for over 300 cycles at a 1C rate. When used as a conducting additive, this CB contributes to high electrical conductivity and increase of ICE and the reversible capacity for LIB and NIB anode materials. These results are expected to have a significant impact on LIBs and NIBs.
Ki-Hun Nam; Keun Hwa Chae; Jeong-Hee Choi; Ki-Joon Jeon; Cheol-Min Park. Superior carbon black: High-performance anode and conducting additive for rechargeable Li- and Na-ion batteries. Chemical Engineering Journal 2021, 417, 129242 .
AMA StyleKi-Hun Nam, Keun Hwa Chae, Jeong-Hee Choi, Ki-Joon Jeon, Cheol-Min Park. Superior carbon black: High-performance anode and conducting additive for rechargeable Li- and Na-ion batteries. Chemical Engineering Journal. 2021; 417 ():129242.
Chicago/Turabian StyleKi-Hun Nam; Keun Hwa Chae; Jeong-Hee Choi; Ki-Joon Jeon; Cheol-Min Park. 2021. "Superior carbon black: High-performance anode and conducting additive for rechargeable Li- and Na-ion batteries." Chemical Engineering Journal 417, no. : 129242.
Air pollution caused by particulate matter (PM) has become a serious issue, and significant research has focused on managing large stationary emission sources, i.e., the primary sources of PM. Currently, the U.S. Environmental Protection Agency (EPA) Method 201A and ISO 23210 are predominantly employed to measure the PM emissions at large stationary sources. Method 201A is designated as a standard test method in Korea, but it is difficult to measure PM10 and PM2.5 simultaneously owing to the size of the full-set cyclone. In large stationary emission sources, the use of a serial connection of PM10 and PM2.5 cyclones is unsuitable for measurements at conventional sampling ports featuring diameters of approximately 100 mm. Therefore, in this study, PM10 and PM2.5 cyclones were developed to replace the cyclones currently used in Method 201A. The developed cyclones featured a cutoff diameter, which was confirmed by numerical and experimental analyses that were close to Method 201A. Moreover, there was an increase in the stiffness of collection efficiency. The hook adaptor, which is a key accessory used in Method 201A, was found to be applicable to the newly developed cyclones. This alternative method will help reduce the measurement time by simultaneously measuring TSP, PM10, and PM2.5 and eliminates the costs of installing or refurbishing additional sampling ports at existing large stationary sources.
Jong-Sang Youn; Sehyun Han; Jae-Seong Yi; Dae-Il Kang; Kee-Won Jang; Yong-Won Jung; Young-Kwon Park; Ki-Joon Jeon. Development of PM10 and PM2.5 cyclones for small sampling ports at stationary sources: Numerical and experimental study. Environmental Research 2020, 193, 110507 .
AMA StyleJong-Sang Youn, Sehyun Han, Jae-Seong Yi, Dae-Il Kang, Kee-Won Jang, Yong-Won Jung, Young-Kwon Park, Ki-Joon Jeon. Development of PM10 and PM2.5 cyclones for small sampling ports at stationary sources: Numerical and experimental study. Environmental Research. 2020; 193 ():110507.
Chicago/Turabian StyleJong-Sang Youn; Sehyun Han; Jae-Seong Yi; Dae-Il Kang; Kee-Won Jang; Yong-Won Jung; Young-Kwon Park; Ki-Joon Jeon. 2020. "Development of PM10 and PM2.5 cyclones for small sampling ports at stationary sources: Numerical and experimental study." Environmental Research 193, no. : 110507.
Water splitting is one of the efficient ways to produce hydrogen with zero carbon dioxide emission. Thus far, Pt has been regarded as a highly reactive catalyst for the hydrogen evolution reaction (HER); however, the high cost and rarity of Pt significantly hinder its commercial use. Herein, we successfully developed an HER catalyst composed of NiSx (x = 1 or 2) on stainless steel (NiSx/SUS) using electrodeposition and sulfurization techniques. Notably, the electrochemical active surface area(ECSA) of NiSx/SUS was improved more than two orders of magnitude, resulting in a considerable improvement in the electrochemical charge transfer and HER activity in comparison with stainless steel (SUS). The long-term HER examination by linear scan voltammetry (LSV) confirmed that NiSx/SUS was stable up to 2000 cycles.
Jong-Sang Youn; Sangmin Jeong; Inhwan Oh; Sunyoung Park; Hien Mai; Ki-Joon Jeon. Enhanced Electrocatalytic Activity of Stainless Steel Substrate by Nickel Sulfides for Efficient Hydrogen Evolution. Catalysts 2020, 10, 1274 .
AMA StyleJong-Sang Youn, Sangmin Jeong, Inhwan Oh, Sunyoung Park, Hien Mai, Ki-Joon Jeon. Enhanced Electrocatalytic Activity of Stainless Steel Substrate by Nickel Sulfides for Efficient Hydrogen Evolution. Catalysts. 2020; 10 (11):1274.
Chicago/Turabian StyleJong-Sang Youn; Sangmin Jeong; Inhwan Oh; Sunyoung Park; Hien Mai; Ki-Joon Jeon. 2020. "Enhanced Electrocatalytic Activity of Stainless Steel Substrate by Nickel Sulfides for Efficient Hydrogen Evolution." Catalysts 10, no. 11: 1274.
Recently, many literatures report on the excellent performance of MoS2-based NO2 sensing, however, lacking the study on its thermal stability. Here, the insight mechanism in NO2 sensor reactivity of monolayer MoS2 at different temperatures from 25 to 200 °C was investigated. The relative effect of the morphological properties of the sensor and gas sensor reactivity at different temperatures was observed using in situ Raman mapping, optical microscope, and scanning electron microscope to demonstrate the mechanism of temperature-dependent limit of NO2 detection in ppb. By increasing the temperature from 25 to 100 °C, the response of the sensor significantly improves (4.8 % vs. 54.4 %) at 200 ppb, and its limit of NO2 detection strongly decreases (48.0 vs. 6.9 ppb). Interestingly, the sensor performance from 100 to 150 °C is likely equivalent to a limit of detection (LoD) that varies from 8.1 to 6.9 ppb, and the LoD slightly increases to 15.0 ppb at 200 °C. The line damages were found in monolayer MoS2 basal plane by heating the sample up to 200 °C, that affect to the recovery of the NO2 sensor. This study reveals an effective approach that may be useful in developing a gas sensor with a high response and limit of NO2 detection in the ppb scale.
Tri Khoa Nguyen; Sangmin Jeong; Jong-Sang Youn; Seungbae Ahn; Ki-Hun Nam; Cheol-Min Park; Ki-Joon Jeon. Insight into mechanism of temperature-dependent limit of NO2 detection using monolayer MoS2. Sensors and Actuators B: Chemical 2020, 329, 129138 .
AMA StyleTri Khoa Nguyen, Sangmin Jeong, Jong-Sang Youn, Seungbae Ahn, Ki-Hun Nam, Cheol-Min Park, Ki-Joon Jeon. Insight into mechanism of temperature-dependent limit of NO2 detection using monolayer MoS2. Sensors and Actuators B: Chemical. 2020; 329 ():129138.
Chicago/Turabian StyleTri Khoa Nguyen; Sangmin Jeong; Jong-Sang Youn; Seungbae Ahn; Ki-Hun Nam; Cheol-Min Park; Ki-Joon Jeon. 2020. "Insight into mechanism of temperature-dependent limit of NO2 detection using monolayer MoS2." Sensors and Actuators B: Chemical 329, no. : 129138.
Here, we develop a dry eye syndrome (DES) incidence rate prediction model using air pollutants (PM10, NO2, SO2, O3, and CO), meteorological factors (temperature, humidity, and wind speed), population rate, and clinical data for South Korea. The prediction model is well fitted to the incidence rate (R2 = 0.9443 and 0.9388, p < 2.2 × 10−16). To analyze regional deviations, we classify outpatient data, air pollutant, and meteorological factors in 16 administrative districts (seven metropolitan areas and nine states). Our results confirm NO2 and relative humidity are the factors impacting regional deviations in the prediction model.
Jong-Sang Youn; Jeong-Won Seo; Wonjun Park; Sejoon Park; Ki-Joon Jeon. Prediction Model for Dry Eye Syndrome Incidence Rate Using Air Pollutants and Meteorological Factors in South Korea: Analysis of Sub-Region Deviations. International Journal of Environmental Research and Public Health 2020, 17, 4969 .
AMA StyleJong-Sang Youn, Jeong-Won Seo, Wonjun Park, Sejoon Park, Ki-Joon Jeon. Prediction Model for Dry Eye Syndrome Incidence Rate Using Air Pollutants and Meteorological Factors in South Korea: Analysis of Sub-Region Deviations. International Journal of Environmental Research and Public Health. 2020; 17 (14):4969.
Chicago/Turabian StyleJong-Sang Youn; Jeong-Won Seo; Wonjun Park; Sejoon Park; Ki-Joon Jeon. 2020. "Prediction Model for Dry Eye Syndrome Incidence Rate Using Air Pollutants and Meteorological Factors in South Korea: Analysis of Sub-Region Deviations." International Journal of Environmental Research and Public Health 17, no. 14: 4969.
MoS2 has been widely used as a hydrogen evolution reaction (HER) electrocatalyst because of its unique characteristics, such as a tunable band gap, near-zero Gibbs free energy, and earth abundance. However, its low electrical conductivity and the electrochemically inert basal plane of MoS2 decrease the HER performance. Herein, we used graphene and carbon cloth (CC) to boost the electrocatalytic activity of MoS2. Using nickel electrodeposition and chemical vapor deposition (CVD) at high temperature, graphene was grown on carbon cloth (Gr/CC) and a sea-grape-like morphology was formed simultaneously. Finally, Gr/CC was covered up with MoS2 using two-zone CVD (MoS2/Gr/CC), resulting in a three-dimensional (3D) sea-grape-like heterostructure. The MoS2/Gr/CC exhibits outstanding HER performance, with a suitable onset potential (50 mV), low ŋ10 (91 mV, overpotential at 10 mA cm−2), high electrical double layer capacitance (Cdl; 239 mF cm−2), low Tafel slope value (48 mV dec−1), and high stability in 0.5 M H2SO4 for two days at various overpotentials. The 3D sea-grape-like morphology and the synergistic effect of MoS2 and graphene led to the enhanced electrocatalytic activity of MoS2/Gr/CC, indicating much better HER performance than most electrocatalysts based on graphene and MoS2.
Inhwan Oh; Jong-Sang Youn; Young-Kwon Park; Ki-Joon Jeon. Heterostructure of 3D sea-grape-like MoS2/graphene on carbon cloth for enhanced water splitting. Applied Surface Science 2020, 529, 147089 .
AMA StyleInhwan Oh, Jong-Sang Youn, Young-Kwon Park, Ki-Joon Jeon. Heterostructure of 3D sea-grape-like MoS2/graphene on carbon cloth for enhanced water splitting. Applied Surface Science. 2020; 529 ():147089.
Chicago/Turabian StyleInhwan Oh; Jong-Sang Youn; Young-Kwon Park; Ki-Joon Jeon. 2020. "Heterostructure of 3D sea-grape-like MoS2/graphene on carbon cloth for enhanced water splitting." Applied Surface Science 529, no. : 147089.
Water splitting from wastewater has been in the limelight because it has advantages which are hydrogen production and electrochemical oxidation at the same time. For efficient water splitting even in wastewater condition, water splitting electrodes should have cost-effectiveness and high durability. Here, we fabricated highly stable and electrocatalytic graphene on copper-nickel alloy to electrochemically produce hydrogen from wastewater in presence of carbon layer between nickel and copper. The electrode fabrication was performed by alloying the copper with nickel and growing graphene on the surface at the same time. The copper and nickel contents of electrode surface were kept by carbon layer hindering the metal diffusion at high temperature. Highly electrocatalytic activity (onset potential = 95 and 158 mV, Tafel slope = 58 and 80 mV dec−1), high durability and pH independence of graphene on copper-nickel alloy were confirmed in acidic and alkaline wastewater containing formaldehyde.
Inhwan Oh; Jong-Sang Youn; Hari Kang; Kovendhan Manavalan; Sang-Chul Jung; Young-Kwon Park; Ki-Joon Jeon. Enhanced stability and electrocatalytic activity of graphene on copper-nickel alloys for hydrogen production from wastewater. Carbon 2020, 161, 665 -673.
AMA StyleInhwan Oh, Jong-Sang Youn, Hari Kang, Kovendhan Manavalan, Sang-Chul Jung, Young-Kwon Park, Ki-Joon Jeon. Enhanced stability and electrocatalytic activity of graphene on copper-nickel alloys for hydrogen production from wastewater. Carbon. 2020; 161 ():665-673.
Chicago/Turabian StyleInhwan Oh; Jong-Sang Youn; Hari Kang; Kovendhan Manavalan; Sang-Chul Jung; Young-Kwon Park; Ki-Joon Jeon. 2020. "Enhanced stability and electrocatalytic activity of graphene on copper-nickel alloys for hydrogen production from wastewater." Carbon 161, no. : 665-673.
As bisphenol A has been found to cause hormonal disturbances, the natural biomaterial isosorbide is emerging as a substitute. In this study, a method for isosorbide synthesis from sorbitol was proposed by dehydration under high temperature and high pressure reaction. Microporous zeolites and Amberlyst 35 solid acids with various acid strengths and pore characteristics were applied as catalysts. In the synthesis of isosorbide from sorbitol, the acidity of the catalyst was the main factor. MOR and MFI zeolite catalysts with high acid strength and small pore size showed low conversion of sorbitol and low yield of isosorbide. On the other hand, the conversion of sorbitol was high in BEA zeolite with moderate acid strength. Amberlyst 35 solid acid catalysts showed a relatively high conversion of sorbitol, but low yield of isosorbide. The Amberlyst 35 solid acid catalyst without micropores did not show any inhibitory effects on the production of by-products. However, in the BEA zeolite catalyst, which has a relatively large pore structure compared with the MOR and MFI zeolites, the formation of by-products was suppressed in the pores, thereby improving the yield of isosorbide.
Sangmin Jeong; Ki-Joon Jeon; Young-Kwon Park; Byung-Joo Kim; Kyong-Hwan Chung; Sang-Chul Jung. Catalytic Properties of Microporous Zeolite Catalysts in Synthesis of Isosorbide from Sorbitol by Dehydration. Catalysts 2020, 10, 148 .
AMA StyleSangmin Jeong, Ki-Joon Jeon, Young-Kwon Park, Byung-Joo Kim, Kyong-Hwan Chung, Sang-Chul Jung. Catalytic Properties of Microporous Zeolite Catalysts in Synthesis of Isosorbide from Sorbitol by Dehydration. Catalysts. 2020; 10 (2):148.
Chicago/Turabian StyleSangmin Jeong; Ki-Joon Jeon; Young-Kwon Park; Byung-Joo Kim; Kyong-Hwan Chung; Sang-Chul Jung. 2020. "Catalytic Properties of Microporous Zeolite Catalysts in Synthesis of Isosorbide from Sorbitol by Dehydration." Catalysts 10, no. 2: 148.
The sulfur vacancy (Sv) generation in the MoS2 basal plane is an efficient strategy for improving the hydrogen evolution reaction (HER). By using cationic current treatment, the Sv density can be controlled by modifying the setting voltage ranges and treatment time. The Sv generation mechanism was clearly defined using Raman mapping. From the Raman mapping characterizations, for the first time, we experimentally found that Sv tends to be generated next to existing Sv by appearing around cracked/damaged areas or group formations. The S: Mo atomic ratio reduced from 2.02:1 to 1.86:1 after treatment. As a result, the current density at −0.3 V vs RHE sharply increases up to 27-fold in comparison to that with untreated MoS2, and the overpotential of treated MoS2 reaches 222 mV at 10 mA/cm2 with a Tafel slope of 96 mV/decade. Hence, the controllable Sv generation in monolayer MoS2 using a cationic current method can be considered as a fast, simple, and effective process to improve HER performance in large-scale production.
Tri Khoa Nguyen; Sangmin Jeong; Kovendhan Manavalan; Jong-Sang Youn; Cheol-Min Park; Ki-Joon Jeon. Controllable desulfurization in single layer MoS2 by cationic current treatment in hydrogen evolution reaction. Applied Surface Science 2019, 507, 145181 .
AMA StyleTri Khoa Nguyen, Sangmin Jeong, Kovendhan Manavalan, Jong-Sang Youn, Cheol-Min Park, Ki-Joon Jeon. Controllable desulfurization in single layer MoS2 by cationic current treatment in hydrogen evolution reaction. Applied Surface Science. 2019; 507 ():145181.
Chicago/Turabian StyleTri Khoa Nguyen; Sangmin Jeong; Kovendhan Manavalan; Jong-Sang Youn; Cheol-Min Park; Ki-Joon Jeon. 2019. "Controllable desulfurization in single layer MoS2 by cationic current treatment in hydrogen evolution reaction." Applied Surface Science 507, no. : 145181.
MoS2 has been widely researched as a good catalyst for the hydrogen production, however, the electrochemical applications of MoS2 are still limited because of its low electrical conductivity and electrochemically inert basal plane. In this study, hybrids of MoS2 and MoO2 were used to decrease charge transfer resistance of electrodes. The proportions of MoS2 and MoO2 were controlled by soft annealing without a structural change. The coexistence of MoS2−MoO2 was confirmed by Raman and X-ray diffraction analysis, and the change of chemical compositions (MoS2 to MoO2 ratio) were demonstrated by X-ray photoelectron spectroscopy. By controlling the chemical compositions of MoS2 and MoO2, the optimal ratio of MoS2 and MoO2 (3: 1) showed the highly electrocatalytic activity (η10: 198 mV, Tafel: 66.8 mV dec−1) and outstanding long-term stability compared to other ratios of MoS2 and MoO2.
Hari Kang; Jong-Sang Youn; Inhwan Oh; Kovendhan Manavalan; Ki-Joon Jeon. Controllable atomic-ratio of CVD-grown MoS2-MoO2 hybrid catalyst by soft annealing for enhancing hydrogen evolution reaction. International Journal of Hydrogen Energy 2019, 45, 1399 -1408.
AMA StyleHari Kang, Jong-Sang Youn, Inhwan Oh, Kovendhan Manavalan, Ki-Joon Jeon. Controllable atomic-ratio of CVD-grown MoS2-MoO2 hybrid catalyst by soft annealing for enhancing hydrogen evolution reaction. International Journal of Hydrogen Energy. 2019; 45 (3):1399-1408.
Chicago/Turabian StyleHari Kang; Jong-Sang Youn; Inhwan Oh; Kovendhan Manavalan; Ki-Joon Jeon. 2019. "Controllable atomic-ratio of CVD-grown MoS2-MoO2 hybrid catalyst by soft annealing for enhancing hydrogen evolution reaction." International Journal of Hydrogen Energy 45, no. 3: 1399-1408.
This study investigates a new air-washing cleaning system that directly injects compressed air on the filter surface for filter regeneration in a fabric filter (FF) dust collector. A pilot-scale FF is designed to test the new system and to compare it with the conventional pulse-jet cleaning system with regard to filter clogging by fume particles. A pleated filter with a filtration area of 2.4 m2 is installed in the FF and a thermal steel spraying gun is used to supply the fume particles. Pressure drop and particle emission concentration are monitored to examine the effect of the new system on filter regeneration and collection efficiency. The results show that the air-washing cleaning is effective for filter regeneration, as it allows the FF to operate stably for a long time, whereas the pulse-jet cleaning fails to achieve filter regeneration, resulting in a continuously increasing pressure drop. In addition, air-washing cleaning shows better performance on collection efficiency than the pulse-jet cleaning method, as it reduces the outlet particulate matter concentration to less than half that of the pulse-jet cleaning.
HyunWook Cho; Jong-Sang Youn; Inhwan Oh; Yong-Won Jung; Ki-Joon Jeon. A new air-washing method to clean fabric filters clogged with submicron fume particles: A pilot-scale study. Journal of Hazardous Materials 2019, 383, 121186 .
AMA StyleHyunWook Cho, Jong-Sang Youn, Inhwan Oh, Yong-Won Jung, Ki-Joon Jeon. A new air-washing method to clean fabric filters clogged with submicron fume particles: A pilot-scale study. Journal of Hazardous Materials. 2019; 383 ():121186.
Chicago/Turabian StyleHyunWook Cho; Jong-Sang Youn; Inhwan Oh; Yong-Won Jung; Ki-Joon Jeon. 2019. "A new air-washing method to clean fabric filters clogged with submicron fume particles: A pilot-scale study." Journal of Hazardous Materials 383, no. : 121186.
Pt is the most commonly used electrode and catalyst materials for H2 production via water splitting as it provides the highest Gibbs free energy of H2 adsorption (ΔGH) an d overpotential. However, as Pt catalysts are expensive and difficult to mass-produce, several efforts have been made to identify suitable substitutes. Although Cu provides lower ΔGH and overpotential than Pt, it exhibits better catalytic performance than other catalysts and is suitable for H2 production. However, corrosion of Cu may affect its stability of Cu electrode. To overcome this limitation, we have coated a layer of carbon on the copper electrode and then synthesized titanium dioxide-(TiO2-) on the C/Cu electrode for water splitting application. Carbon black (CB) has excellent electrical conductivity and stable resistance for effective working as an electrochemical catalyst, and TiO2 has diverse applications because of its low-cost, non-toxic, and corrosion-resistant characteristics. In this study, TiO2 was synthesized on C/Cu electrodes under UV irradiation for different durations. The optimum irradiation duration was determined to be 15 min via surface and electrochemical analyses. To identify the potential applications of this TiO2–C/Cu electrode, we used artificial wastewater as the electrolyte. The synthesized TiO2–C/Cu electrode exhibited better stability than C/Cu electrode. Further, H2 production with TiO2–C/Cu electrode was higher than that with C/Cu electrode at the same current density. We also investigated the effect of TiO2–C/Cu electrode on decomposition of formaldehyde.
Sangmin Jeong; Jong-Sang Youn; Ki-Joon Jeon. Titanium dioxide-coated copper electrodes for hydrogen production by water splitting. International Journal of Hydrogen Energy 2019, 45, 24037 -24044.
AMA StyleSangmin Jeong, Jong-Sang Youn, Ki-Joon Jeon. Titanium dioxide-coated copper electrodes for hydrogen production by water splitting. International Journal of Hydrogen Energy. 2019; 45 (45):24037-24044.
Chicago/Turabian StyleSangmin Jeong; Jong-Sang Youn; Ki-Joon Jeon. 2019. "Titanium dioxide-coated copper electrodes for hydrogen production by water splitting." International Journal of Hydrogen Energy 45, no. 45: 24037-24044.
The main purpose of this study was to analyze the Korean PM2.5 emissions according to the past, present, and future energy mix scenarios from 1970 to 2035, with the aim of identifying a sustainable, future environmentally friendly energy mix scenario for Korea related to PM2.5 emissions. To calculate the PM2.5 emissions according to an energy mix plan, we assumed two scenarios: (1) Scenario 1 is based on an energy conversion scenario established by the Korean government’s 7th electric power demand supply program; and (2) Scenario 2 is enhancement of fuel cell usage. In Scenario 1, filterable PM2.5 (FPM2.5) emission was calculated as 61,158 ton/year, which includes contributions of anthracite (46.8%), petroleum (39.7%), natural gas (LNG) (10.0%), and LPG (0.1%). In Scenario 2, FPM2.5 emission was calculated as 36,917 ton/year, which includes contributions of petroleum (47.8%), anthracite (40.3%), bituminous coal (10.1%), and LNG (1.7%). Thus, we concluded that the FPM2.5 mitigation effect from fuel cell policy enforcement is about 38.13% higher than the Korean national energy conversion policy. PM2.5 (FPM2.5 + condensable PM2.5 (CPM2.5)) emissions dramatically increased in both energy mix scenarios so that CPM2.5 should be considered when estimating PM2.5 emissions and PM2.5 reduction.
Doo Sung Choi; Jong-Sang Youn; Im Hack Lee; Young-Kwon Park; Byung Jin Choi; Ki-Joon Jeon. Analysis of National PM2.5 (FPM and CPM) Emissions by Past, Current, and Future Energy Mix Scenarios in the Republic of Korea. Sustainability 2019, 11, 4289 .
AMA StyleDoo Sung Choi, Jong-Sang Youn, Im Hack Lee, Young-Kwon Park, Byung Jin Choi, Ki-Joon Jeon. Analysis of National PM2.5 (FPM and CPM) Emissions by Past, Current, and Future Energy Mix Scenarios in the Republic of Korea. Sustainability. 2019; 11 (16):4289.
Chicago/Turabian StyleDoo Sung Choi; Jong-Sang Youn; Im Hack Lee; Young-Kwon Park; Byung Jin Choi; Ki-Joon Jeon. 2019. "Analysis of National PM2.5 (FPM and CPM) Emissions by Past, Current, and Future Energy Mix Scenarios in the Republic of Korea." Sustainability 11, no. 16: 4289.
Nanoparticle and HAP emissions from 3D printers and their deposition behavior in the human respiratory system were evaluated.
Jong-Sang Youn; Jeong-Won Seo; Sehyun Han; Ki-Joon Jeon. Characteristics of nanoparticle formation and hazardous air pollutants emitted by 3D printer operations: from emission to inhalation. RSC Advances 2019, 9, 19606 -19612.
AMA StyleJong-Sang Youn, Jeong-Won Seo, Sehyun Han, Ki-Joon Jeon. Characteristics of nanoparticle formation and hazardous air pollutants emitted by 3D printer operations: from emission to inhalation. RSC Advances. 2019; 9 (34):19606-19612.
Chicago/Turabian StyleJong-Sang Youn; Jeong-Won Seo; Sehyun Han; Ki-Joon Jeon. 2019. "Characteristics of nanoparticle formation and hazardous air pollutants emitted by 3D printer operations: from emission to inhalation." RSC Advances 9, no. 34: 19606-19612.
For water electrolysis, a rare earth material (eg., platinum) is often used as an electrode, but because of the high cost and toxicity of chemicals, researchers are searching for cost effective and eco-friendly alternative materials. Various alloys and metals have been long explored for use as electrode materials in different media. Stainless steel (SS 304) electrodes are cost effective and have a large surface area; further their catalytic performance is comparable to that of carbon coated noble metals cathodes. Stainless steel has good mechanical properties and durability so it is widely used in desalination plants, oil and gas industries, ship building, etc. However, over a period of time it corrodes very quickly in saline water. To improve the stability and durability of the electrodes (i.e., to minimize corrosion), we anneal the samples under two different sets of conditions and test the electrodes in 3.5% NaCl solution. The anodic peak (−0.25 V) observed for bare stainless steel result from the formation of iron (II) hydroxide [Fe(OH)2]. The Raman bands observed at 210 and 274 cm−1 for bare stainless steel result from the formation of α-Fe2O3 owing to partial, anodic, and cathodic reactions occurring on the electrode which disrupts the surface layers. High intensity X-ray diffraction (XRD) and Raman peaks of Cr2O3 and MnCr2O4 observed in argon and hydrogen annealed sample after cyclic voltammetry reveal that this sample is more stable than bare and air annealed samples. XRD reveals mixed oxide phases in addition to eskolaite and magnetite phases. Scanning electron microscope (SEM) images show that although the air-annealed sample has a soft, spongy structure, Na and Cl ions are adsorbed in the voids on the outer surface of the electrode leading to quick degradation. For the air-annealed sample the oxide appears to adhere poorly to the stainless steel. Oxygen (ie., oxide composition) may play a key role in adherence and growth of Cr2O3 formed at high temperature. X-ray photoelectron spectroscopy (XPS) reveals that large amounts of Cr and Mn are dissolved/corroded into the electrolyte for air annealed sample which is in good agreement with the Raman and SEM results.
M. Kovendhan; Hari Kang; Sangmin Jeong; Jong-Sang Youn; Inhwan Oh; Young-Kwon Park; Ki-Joon Jeon. Study of stainless steel electrodes after electrochemical analysis in sea water condition. Environmental Research 2019, 173, 549 -555.
AMA StyleM. Kovendhan, Hari Kang, Sangmin Jeong, Jong-Sang Youn, Inhwan Oh, Young-Kwon Park, Ki-Joon Jeon. Study of stainless steel electrodes after electrochemical analysis in sea water condition. Environmental Research. 2019; 173 ():549-555.
Chicago/Turabian StyleM. Kovendhan; Hari Kang; Sangmin Jeong; Jong-Sang Youn; Inhwan Oh; Young-Kwon Park; Ki-Joon Jeon. 2019. "Study of stainless steel electrodes after electrochemical analysis in sea water condition." Environmental Research 173, no. : 549-555.