이광희
@korea.ac.kr
Korea University
Scopus Publications
Scopus Publications
Eun-Jung Park, Mi-Jin Yang, Min-Sung Kang, Young-Min Jo, Cheolho Yoon, Yunseo Lee, Dong-Wan Kim, Gwang-Hee Lee, Ik-Hwan Kwon, and Jin-Bae Kim
Elsevier BV
Eun-Jung Park, Mi-Jin Yang, Min-Sung Kang, Young-Min Jo, Cheolho Yoon, Hyun-bin Kim, Dong-Wan Kim, Gwang-Hee Lee, Ik-Hwan Kwon, Hee-Jin Park,et al.
Elsevier BV
Myeong-Chang Sung, Gwang-Hee Lee, and Dong-Wan Kim
Elsevier BV
Gwang-Hee Lee, Myeong-Chang Sung, and Dong-Wan Kim
Elsevier BV
Min-Sung Kang, Gwang-Hee Lee, Ik Hwan Kwon, Mi-Jin Yang, Min Beom Heo, Jae-Won Choi, Tae Geol Lee, Cheol-Ho Yoon, Bosung Baek, Myeong-Chang Sung,et al.
Elsevier BV
Heewon Yoo, Gwang‐Hee Lee, Myeong‐Chang Sung, and Dong‐Wan Kim
Wiley
Gwang‐Hee Lee, Heewon Yoo, and Dong‐Wan Kim
Wiley
Min-Sung Kang, Gwang-Hee Lee, Mi-Jin Yang, Myeong-Chang Sung, Hyoung-Yun Han, Byoung-Seok Lee, Bosung Baek, Dong-Wan Kim, and Eun-Jung Park
Informa UK Limited
Abstract Pulmonary effects of inhaled microfibers are an emerging public health concern. In this study, we investigated toxicity following pulmonary exposure to synthetic polyethylene oxide fibroin (PEONF) and silk fibroin (SFNF) nanofibers and the cellular responses. When instilled intratracheally weekly for four weeks, body weight gain was significantly reduced in female mice exposed to the higher dose of SFNF when compared with the control group. The total number of cells in the lungs was more significant in all treated groups than in the control, whereas the relative portion of neutrophils and eosinophils increased significantly only in female mice exposed to SFNF. Both types of nanofibers induced notable pathological changes and increased pulmonary expression of MCP-1α, CXCL1, and TGF-β. More importantly, blood calcium, creatinine kinase, sodium, and chloride concentration were affected significantly, showing sex- and material-dependent differences. The relative portion of eosinophils increased only in SFNF-treated mice. In addition, both types of nanofibers induced necrotic and late apoptotic cell death in alveolar macrophages after 24 h of exposure, with accompanying oxidative stress, increased NO production, cell membrane rupture, intracellular organelle damage, and intracellular calcium accumulation. Additionally, multinucleated giant cells were formed in cells exposed to PEONF or SFNF. Taken together, the findings indicate that inhaled PEONF and SFNF may cause systemic adverse health effects with lung tissue damage, showing differences by sex- and material. Furthermore, PEONF- and SFNF-induced inflammatory response may be partly due to the low clearance of dead (or damaged) pulmonary cells and the excellent durability of PEONF and SFNF.
Myeong‐Chang Sung, Gwang‐Hee Lee, and Dong‐Wan Kim
Wiley
AbstractEfficient electrocatalysis at the cathode is essential for overcoming the limitations of LiO2 batteries such as poor stability and low rate capability. Herein, we systematically studied the kinetic behavior of a LiO2 battery comprising perovskite La0.8Sr0.2VO3 nanofibers formed by partial Sr‐cation doping and V cations with multiple oxidation states. Compared with undoped LaVO3 and La0.8Sr0.2VO4 nanofibers, perovskite La0.8Sr0.2VO3 nanofibers exhibited an improved capacity of 2000 mA g−1, and a 20‐times‐longer cycle life in LiO2 batteries. X‐ray photoelectron spectroscopy, electron paramagnetic resonance spectroscopy, and photoluminescence analyses revealed that the performance variations mainly originated from crystal defects, which modulate oxygen reduction/evolution kinetics. Through in situ Raman analysis, we showed that these structural defects are closely related to the oxygen reduction/evolution behavior of La0.8Sr0.2VO3 nanofibers and result in fewer parasitic reactions. This study offers insights into the potential rate capability of LiO2 batteries and related devices.image
Jiae Seo, Gwang‐Hee Lee, Joon Hur, Myeong‐Chang Sung, Ji‐Hun Seo, and Dong‐Wan Kim
Wiley
Yoon Seon Kim, Gwang-Hee Lee, Bobae Ju, and Dong-Wan Kim
Elsevier BV
Abstract Nitrogen/Sulfur dual-doped carbon cubes with built-in CoS2 nanoparticles (CoS2@NS-C cubes) as an electrocatalyst are developed to improve the high-rate and long-term performance of lithium-oxygen batteries. The CoS2@NS-C cubes were synthesized by coprecipitation between a cobalt salt and 7,7,8,8-tetracyanoquinodimethane (TCNQ) and subsequent thermal sulfidation. TCNQ acted as the coordination polymer for a cube shape and as the nitrogen source for nitrogen-dopants. The CoS2@NS-C cubes comprise uniformly distributed CoS2 nanoparticles in a nitrogen/sulfur dual-doped carbon matrix, providing fast catalytic activity for oxygen reduction/evolution reactions. The CoS2@NS-C cubes exhibited a high-rate performance of 5000 mA g−1 as well as long-term performance of > 100 cycles with a current density of 2000 mA g−1. These results confirmed the enhanced performance of the lithium-oxygen battery, with fast charging capability.
Gwang-Hee Lee, Yoon Seon Kim, Myeong-Chang Sung, and Dong-Wan Kim
Elsevier BV
Abstract The design of electrode materials plays a significant role in achieving the desired electrochemical performance for lithium-ion batteries; the design should provide a fast electronic transport pathway and prevent excessive volume variation. Herein, ultrafine CoP nanoparticles were successfully embedded in a nitrogen-doped carbon cube (NP-CC), which was synthesized from 7,7,8,8-tetracyanoquinodimethane (TCNQ)-derived carbon. CoP@NP-CC was synthesized by the chemical interaction between cobalt iodide and TCNQ, followed by thermal phosphidation. When applied as an anode material for lithium-ion batteries, CoP@NP-CC exhibited outstanding rate capability with a long-term cycling performance. The excellent electrochemical performance is attributed to the monodisperse construction of CoP nanoparticles embedded in NP-CC, which relieved the volume change of CoP nanoparticles and provided a highly conductive matrix. This design of a monodisperse cubic architecture can be extended to other transition-metal-based electrode materials to attain a high performance of lithium-ion batteries.
Hyoung‐Yun Han, Mi‐Jin Yang, Cheolho Yoon, Gwang‐Hee Lee, Dong‐Wan Kim, Tae‐Won Kim, Minjeong Kwak, Min Beom Heo, Tae Geol Lee, Soojin Kim,et al.
Wiley
This year, France banned the application of titanium dioxide nanoparticles as a food additive (hereafter, E171) based on the insufficient oral toxicity data. Here, we investigated the subchronic toxic responses of E171 (0, 10, 100, and 1,000 mg/kg) and tried to elucidate the possible toxic mechanism using AGS cells, a human stomach epithelial cell line. There were no dose‐related changes in the Organisation for Economic Cooperation and Development test guideline‐related endpoints. Meanwhile, E171 deeply penetrated cells lining the stomach tissues of rats, and the IgM and granulocyte‐macrophage colony‐stimulating factor levels were significantly lower in the blood from rats exposed to E171 compared with the control. The colonic antioxidant protein level decreased with increasing Ti accumulation. Additionally, after 24‐h exposure, E171 located in the perinuclear region of AGS cells and affected expression of endoplasmic reticulum stress‐related proteins. However, cell death was not observed up to the used maximum concentration. A gene profile analysis also showed that immune response‐related microRNAs were most strongly affected by E171 exposure. Collectively, we concluded that the NOAEL of E171 for 90 days repeated oral administration is between 100 and 1,000 mg/kg for both male and female rats. Additionally, further study is needed to clarify the possible carcinogenesis following the chronic accumulation in the colon.
Eun-Jung Park, Cheolho Yoon, Ji-Seok Han, Gwang-Hee Lee, Dong-Wan Kim, Eun-Jun Park, Hyun-Ji Lim, Min-Sung Kang, Hyoung-Yun Han, Hyun-Joo Seol,et al.
Elsevier BV
Despite numerous reports that ambient particulate matter is a key determinant for human health, toxicity data produced based on physicochemical properties of particulate matters is very lack, suggesting lack of scientific evidence for regulation. In this study, we sampled inhalable particulate matters (PM10) in northern Seoul, Korea. PM10 showed atypical- and fiber-type particles with the average size and the surface charge of 1,598.1 ± 128.7 nm and -27.5 ± 2.8, respectively, and various toxic elements were detected in the water extract. On day 90 after the first pulmonary exposure, total cell number dose-dependently increased in the lungs of both sexes of mice. PM10 induced Th1-dominant immune response with pathological changes in both sexes of mice. Meanwhile, composition of total cells and expression of proteins which functions in cell-to-cell communication showed different trends between sexes. Following, male and female mice were mated to identify effects of PM10 to the next generation. PM10 remained in the lung of dams until day 21 after birth, and the levels of IgA and IgE increased in the blood of dams exposed to the maximum dose compared to control. In addition, the interval between births of fetuses, the number of offspring, the neonatal survival rate (day 4 after birth) and the sex ratio seemed to be affected at the maximum dose, and particularly, all offspring from one dam were stillborn. In addition, expression of HIF-1α protein increased in the lung tissue of dams exposed to PM10, and level of hypoxia-related proteins was notably enhanced in PM10-exposed bronchial epithelial cells compared to control. Taken together, we suggest that inhaled PM10 may induce Th1-shifting immune response in the lung, and that it may affect reproduction (fetus development) by causing lung hypoxia. Additionally, we propose that further study is needed to identify particle-size-dependent effects on development of the next generation.
Heewon Yoo, Gwang-Hee Lee, and Dong-Wan Kim
Elsevier BV
Abstract In this study, FeSe hollow spheroids were prepared for application as cathode electrocatalysts in Li–O2 batteries. The hollow spheroids were synthesized through hydrothermal and thermal selenization processing based on a silk–fibroin template. At the high current rate of 1000 mA g−1, the FeSe spheroids exhibited higher reversibility (100 cycles) and a similar voltage gap to that at 200 mA g−1. Therefore, FeSe hollow spheroids exhibit high oxygen reduction/evolution catalytic efficiency for high–rate Li–O2 batteries. This result was demonstrated via comparison of the oxygen reduction/evolution kinetics of FeSe and Fe2O3 hollow spheroids using electrochemical impedance spectroscopy.
Yoon Seon Kim, Gwang-Hee Lee, Myeong-Chang Sung, and Dong-Wan Kim
Elsevier BV
Abstract Perovskite ABO3 provides higher catalytic activity than binary metal oxides owing to crystallographic defects and oxygen vacancies due to the multivalence of the A and B cations. In this study, perovskite SeZnO3 nanosheets were synthesized via a simple wet chemistry method with sodium dodecyl sulfate as the surfactant. Material surface analysis using O 1s X-ray photo-electron spectroscopy confirmed an Ovacancy concentration of 50%, confirming the presence of large amounts of defects on the surface of the SeZnO3 nanosheets. The lithium-oxygen batteries with SeZnO3 nanosheet as an oxygen-electrode electrocatalyst exhibited a high reversibility (140 cycles) and a stable rate capability (50–500 mA g−1). Additionally, electrochemical impedance spectroscopy measurements indicated that the electronic conductivity of a SeZnO3 nanosheet was higher than that of ZnO. Therefore, we propose that the unique SeZnO3 structure exhibits excellent catalytic activity and electrical conductivity and can serve as a route towards improved lithium-oxygen batteries.
Eun-Jung Park, Min-Sung Kang, Seung-Woo Jin, Tae Geol Lee, Gwang-Hee Lee, Dong-Wan Kim, Eun-Woo Lee, Junhee Park, Inhee Choi, and Youngmi Kim Pak
Informa UK Limited
In our previous study, 20 nm-sized amorphous silica nanoparticles (20-SiNPs), but not 50 nm-sized amorphous silica nanoparticles (50-SiNPs), induced pulmonary inflammatory response in rats exposed repeatedly for 14 days (12.5, 25, and 50 μg/time, total six times). In this study, we tried to clarify the causes of different responses induced by both SiNPs using mice (12.5, 25, and 50 μg/lung) and mouse alveolar macrophage cells. When exposed to alveolar macrophage cells for 24 h, both SiNPs decreased cell viability and enhanced ROS generation compared to controls. The 20- and 50-SiNPs also formed giant and autophagosome-like vacuoles in the cytoplasm, respectively. Structural damage of organelles was more pronounced in 20-SiNPs-treated cells than in 50-SiNPs-treated cells, and an increased mitochondrial membrane potential and mitochondrial calcium accumulation were observed only in the 20-SiNPs-treated cells. Additionally, a single intratracheal instillation of both sizes of SiNPs to mice clearly elevated the relative proportion of neutrophils and inhibited differentiation of macrophages and expression of an adhesion molecule. Meanwhile, interestingly, the total number of pulmonary cells and the levels of pro-inflammatory mediators more notably increased in the lungs of mice exposed to 20-SiNPs compared to 50-SiNPs. Given that accumulation of giant vacuoles and dilation of the ER and mitochondria are key indicators of paraptosis, we suggest that 20-SiNPs-induced pulmonary inflammation may be associated with paraptosis of alveolar macrophages.
Eun-Jung Park, Soo Nam Kim, Cheolho Yoon, Jae-Woo Cho, Gwang-Hee Lee, Dong-Wan Kim, Junhee Park, Inhee Choi, Seung Hyeun Lee, Jeongah Song,et al.
Informa UK Limited
Abstract Recently, some researchers have demonstrated that inhaled zinc oxide nanoparticles (ZnONPs) induce an acute systemic inflammatory response in workers. Considering nonhuman primates are preferably considered an animal model for translational research due to their proven similarity with humans in terms of genetics and physiology, we intratracheally instilled ZnONPs to cynomolgus monkey for 14 days and identified the toxic mechanism and bioaccumulation. ZnONPs were rapidly ionized or aggregated in a simulated pulmonary fluid, and they attracted neutrophils to the lungs and increased the pulmonary level of inflammatory mediators. Additionally, thickened alveolar walls, fibrin clots, and hemorrhages were observed in the lungs of the monkeys instilled with the higher dose accompanied by cell debris in the alveolar ducts and alveoli. Dark-field microscopy images revealed translocation of ZnONPs into other tissues accompanied by an increase in the relative weight of livers to body weight. In addition, when instilled at the higher dose, the albumin/globulin ratio notably decreased compared to the control, whereas the C-reactive protein (CRP) level was significantly elevated. ZnONPs also clearly induced apoptotic cell death in a 24 h exposure to alveolar macrophages. Taken together, part of inhaled ZnONPs may be ionized in the lung, resulting in acute toxic effects, including cell death and tissue damage, and the rest may move to other tissues in the form of particles, causing a systemic inflammatory response. Based on the proven evidence among workers, we also suggest that the CRP level can be recommended as a biomarker for ZnONPs-induced adverse health effects.
Eun-Jung Park, Soo-Nam Kim, Gwang-Hee Lee, Young-Min Jo, Cheolho Yoon, Dong-Wan Kim, Jae-Woo Cho, Ji-Seok Han, Sang Jin Lee, Eunsol Seong,et al.
Elsevier BV
In this study, we aimed to identify a toxic mechanism and the potential health effects of ambient dusts in an underground subway station. At 24 h exposure to human bronchial epithelial (BEAS-2B) cells (0, 2.5, 10, and 40 μg/mL), dusts located within autophagosome-like vacuoles, whereas a series of autophagic processes appeared to be blocked. The volume, potential and activity of mitochondria decreased in consistent with a condensed configuration, and the percentage of late apoptotic cells increased accompanying S phase arrest. While production of reactive oxygen species, expression of ferritin (heavy chain) protein, secretion of IL-6, IL-8 and matrix metalloproteinases, and the released LDH level notably increased in dust-treated cells (40 μg/mL), intracellular calcium level decreased. At day 14 after a single instillation to mice (0, 12.5, 50, and 200 μg/head), the total number of cells increased in the lungs of dust-treated mice with no significant change in cell composition. The pulmonary levels of TGF-β, GM-CSF, IL-12 and IL-13 clearly increased following exposure to dusts, whereas that of CXCL-1 was dose-dependently inhibited. Additionally, the population of cytotoxic T cells in T lymphocytes in the spleen increased relative to that of helper T cells, and the levels of IgA and IgM in the bloodstream were significantly reduced in the dust-treated mice. Subsequently, to improve the possibility of extrapolating our findings to humans, we repeatedly instilled dusts (1 time/week, 4 weeks, 0.25 and 1.0 mg/head) to monkeys. The total number of cells, the relative portion of neutrophils, the level of TNF-α significantly increased in the lungs of dust-treated monkeys, and the expression of cytochrome C was enhanced in the lung tissues. Meanwhile, the pulmonary level of MIP-α was clearly reduced, and the expression of caveolin-1 was inhibited in the lung tissues. More importantly, inflammatory lesions, such as granuloma, were seen in both mice and monkeys instilled with dusts. Taken together, we conclude that dusts may impair the host's immune function against foreign bodies by inhibiting the capacity for production of antibodies. In addition, iron metabolism may be closely associated with dust-induced cell death and inflammatory response.
Gwang-Hee Lee, Myeong-Chang Sung, Yoon Seon Kim, Bobae Ju, and Dong-Wan Kim
American Chemical Society (ACS)
We report a technique for effectively neutralizing the generation of harmful superoxide species, the source of parasitic reactions, in lithium-oxygen batteries to generate stable substances. In organic electrolytes, organogermanium (Propa-germanium, Ge-132) nanowires can suppress solvated superoxide and induce strong surface-adsorption reaction due to their high anti-superoxide disproportionation activity. Resultantly, the effect of organogermanium nanowires mitigate toxic oxidative stress to stabilize organic electrolytes and promote good Li2O2 growth. These factors led to long duration of the electrolytes and impressive rechargeability of lithium-oxygen batteries.
Eun-Jung Park, Eunsol Seong, Min-Sung Kang, Gwang-Hee Lee, Dong-Wan Kim, Ji-Seok Han, Hyun-Ji Lim, Seung Hyeun Lee, and Hyoung-Yun Han
Elsevier BV
Abstract
Due to the pandemic of coronavirus disease 2019, the use of disinfectants is rapidly increasing worldwide. Didecyldimethylammonium chloride (DDAC) is an EPA-registered disinfectant, it was also a component in humidifier disinfectants that had caused idiopathic pulmonary diseases in Korea. In this study, we identified the possible pulmonary toxic response and mechanism using human bronchial epithelial (BEAS-2B) cells and mice. First, cell viability decreased sharply at a 4 μg/mL of concentration. The volume of intracellular organelles and the ROS level reduced, leading to the formation of apoptotic bodies and an increase of the LDH release. Secretion of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) and matrix metalloproteinase-1 also significantly increased. More importantly, lamellar body-like structures were formed in both the cells and mice exposed to DDAC, and the expression of both the indicator proteins for lamellar body (ABCA3 and Rab11a) and surfactant proteins (A, B, and D) was clearly enhanced. In addition, chronic fibrotic pulmonary lesions were notably observed in mice instilled twice (weekly) with DDAC (500 μg), ultimately resulting in death. Taken together, we suggest that disruption of pulmonary surfactant homeostasis may contribute to DDAC-induced cell death and subsequent pathophysiology and that the formation of lamellar body-like structures may play a role as the trigger. In addition, we propose that the cause of sudden death of mice exposed to DDAC should be clearly elucidated for the safe application of DDAC.
Eun-Jung Park, Ji-Seok Han, Eun-Jun Park, Eunsol Seong, Gwang-Hee Lee, Dong-Wan Kim, Hwa-Young Son, Hyoung-Yun Han, and Byoung-Seok Lee
Elsevier BV
With the increased distribution of microplastics in the environment, the potential for harmful effects on human health and ecosystems have become a global concern. Considering that polyethylene microplastics (PE-MPs) are among the most produced plastics worldwide, we administered PE-MPs (0.125, 0.5, 2 mg/day/mouse) by gavage to mice (10 mice/sex/dose) for 90 days. Compared to control, the body weight gain was significantly reduced in the male mice, and the proportion of neutrophils in the blood stream clearly increased in both sexes of mice. Persistence of a PE-MPs-like material and migration of granules to the mast cell membrane and accumulation of damaged organelles were observed in the stomachs and the spleens from the treated dams, respectively. Additionally, the IgA level in the blood stream was significantly elevated in the dams administered with PE-MPs compared to control, and the subpopulation of lymphocytes within the spleen was altered. Following, we performed an additional study to screen the effects of PE-MPs on reproduction and development (5 mice/sex/dose). Importantly, number of live births per dam, the sex ratio of pups, and body weight of pups was notably altered in groups treated with PE-MPs compared to the control group. Additionally, PE-MPs affected the subpopulation of lymphocytes within the spleen of the offspring, as did in the dams. Therefore, we propose that reproductive and developmental toxicity testing is warranted to evaluate the safety of microplastics. Additionally, we suggest that the IgA level may be used as a biomarker for harmful effects following exposure on microplastics.
Gwang-Hee Lee, Yoon Seon Kim, and Dong-Wan Kim
Elsevier BV
Abstract FePO4 and porous Fe2P2O7 laundry-ball-like nanostructures (FePO4 LBs and p-Fe2P2O7 LBs, respectively) were prepared to investigate their functionalities as oxygen-electrode (O2-electrode) electrocatalysts in Li–O2 batteries. These structures were synthesized in two steps, via hydrothermal and thermal reactions. FePO4 LBs were synthesized through thermal dehydrogenation of as-prepared FePO4·2H2O precursors (FePO4·2H2O → FePO4 + 2H2O), and p-Fe2P2O7 LBs were synthesized through thermochemical reduction of same precursors under an H2 atmosphere (2FePO4·2H2O + H2 → Fe2P2O7 + 5H2O). As an O2-electrode electrocatalyst in Li–O2 cells, p-Fe2P2O7 LBs exhibited a higher discharge capacity (30,000 mA h gcatalyst–1 at a current density of 500 mA gcatalyst–1), higher reversibility (300 cycles at a current rate of 500 mA gcatalyst–1), and lower voltage gap, compared to FePO4 LBs. These superior performances of p-Fe2P2O7 LBs result from the Fe2+/Fe3+ redox effect and porous structure, which enhance the oxygen reduction or evolution reaction activities.
Hyoung-Yun Han, Jae-Woo Cho, Eunsol Seong, Eun-Jun Park, Gwang-Hee Lee, Dong-Wan Kim, Young-Su Yang, Jung-Hwa Oh, Seokjoo Yoon, Tae Geol Lee,et al.
Elsevier BV
Due to mass production and extensive use, the potential adverse health effects of amorphous silica nanoparticles (ASiNPs) have received a significant attention from the public and researchers. However, the relationship between physicochemical properties of ASiNPs and their health effects is still unclear. In this study, we manufactured two types of ASiNPs of different diameters (20 and 50 nm) and compared the toxic response induced in rats after intratracheal instillation (75, 150 or 300 μg/rat). There were no dose-related differences in mortality, body weight gain or organ weight between the groups. However both types of ASiNPs significantly decreased the proportion of neutrophils in male rats, whereas the levels of hemoglobin and hematocrit were markedly reduced only in female rats instilled with 20 nm-ASiNPs. ASiNPs-induced lung tissue damage seemed to be more evident in the 20 nm ASiNP-treated group and in female rats than male rats. Similarly, expression of caveolin-1 and matrix metalloproteinase-9 seemed to be most notably enhanced in female rats treated with 20 nm-ASiNPs. The total number of bronchial alveolar lavage cells significantly increased in rats instilled with 20 nm-ASiNPs, accompanying a decrease in the proportion of macrophages and an increase in polymorphonuclear leukocytes. Moreover, secretion of inflammatory mediators clearly increased in human bronchial epithelial cells treated with 20 nm-ASiNPs, but not in those treated with 50 nm-ASiNPs. These results suggest that pulmonary effects of ASiNPs depend on particle size. Sex-dependent differences should also be carefully considered in understanding nanomaterial-induced adverse health effects.
Bobae Ju, Hee Jo Song, Gwang-Hee Lee, Myeong-Chang Sung, and Dong-Wan Kim
Elsevier BV
Abstract Lithium–oxygen batteries (LOBs) are considered as next-generation energy storage systems owing to their high energy densities. In order to achieve high-performance LOBs, it is necessary to develop efficient electrocatalysts that exhibit reversible formation and decomposition of discharge products on the oxygen-electrode side. In this study, single-crystalline NiS2 nanosheets (NiS2-NSs) are fabricated as an efficient electrocatalyst in an oxygen-electrode for high-performance LOBs. Ni(OH)2-NSs are prepared through a hydrothermal reaction and subsequently reacted with sulfur by a solid/gas phase reaction process to form NiS2-NSs. As an electrocatalyst in an oxygen-electrode, the single-crystalline NiS2-NSs can reversibly form and decompose the discharge products during the discharging and charging processes, respectively. In particular, the NiS2-NSs more effectively decompose the discharge products compared to the Ni(OH)2-NSs owing to its high affinity to oxygenated species. In addition, the NiS2-NSs exhibit a long-term cyclability over 300 cycles at a current density of 1000 mA g−1 with a cut-off capacity of 1000 mA h g−1. Moreover, NiS2-NSs without conducting agent exhibit an electrocatalytic activity and its LOB performance can be further maximized through addition of a redox mediator.