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Acceleration of Singlet Oxygen Evolution by Superoxide Dismutase Mimetics in Lithium–Oxygen Batteries. by Joo-Eun Kim;Hyun-Wook Lee;Won-Jin Kwak Advanced Functional Materials 2022, 32(52); https://doi.org/10.1002/adfm.202209012 Abstract Side reactions caused by reactive oxygen species (e.g., superoxide and singlet oxygen) are limiting factors in the lithium–oxygen batteries (LOBs). Superoxide dismutase mimetics (SODms), which suppress superoxide-triggered side reactions by accelerating the disproportionation reaction during discharge, are introduced as soluble additives in the LOBs. However, although SODms promote the disproportionation reaction, which is the main pathway for singlet oxygen evolution, the correlation between SODms and singlet oxygen has not been verified. Here, 4-carboxy-TEMPO is selected as a representative SODm that effectively promotes the disproportionation reaction and chemically verifies acceleration of singlet oxygen evolution. Furthermore, by using quencher, it is reported that the release of singlet oxygen evolved by the SODm is decreased. Because this study closely examines the relationship between the additives and singlet oxygen, it is believed that this study provides an important reference for the development of additives for the practical application of LOBs.
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- 작성자박은영
- 작성일2023-01-16
- 620
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24
- 작성자박은영
- 작성일2023-01-16
- 612
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22
- 작성자박은영
- 작성일2023-01-16
- 694
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20
- 작성자박은영
- 작성일2023-01-16
- 624
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18
- 작성자박은영
- 작성일2023-01-16
- 617
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Effects of Oxygen Vacancies in a Zinc Oxide Electron Transport Layer on Long-Term Degradation by Shin Young Ryu;Na Young Ha;Yeong Hwan. Ahn;Ji-Yong Park;Soonil Lee ACS Applied Energy Materials 2022, 5(8); https://doi.org/10.1021/acsaem.2c01325 Abstract We studied changes in current density–voltage (J–V) characteristics of organic solar cells (OSCs) with a ZnO electron-transport layer (ETL) with respect to illumination intensity and aging time. Unlike an encapsulated OSC that remained almost intact up to 195 h, an unsealed OSC showed steady degradation. To elucidate the origin of long-term degradation, we carried out systematic simulations and identified six parameters that were responsible for aging effects in dark J–V curves. Among these six parameters, additional adjustments were necessary only for donor density and energy-barrier height, both of which were linked to a ZnO ETL, to reproduce a set of J–V curves concomitantly measured at 12 illumination conditions. We note that oxygen vacancies in ZnO behave as electron donors and, additionally, result in dipole-moment losses. Consequently, reoxidation of a ZnO ETL resulted from slow diffusion of ambient oxygen or water, lowered the electron quasi-Fermi level, and increased the energy-barrier height. On the contrary, light-induced generation of oxygen vacancies, a short-term effect that disappears after turning illumination off, shifted the electron quasi-Fermi level upward and decreased the energy-barrier height. Because light-induced effects counteracted those of long-term reoxidation, light intensity-dependent variations in J–V curves became more prominent with aging. KEYWORDS: organic solar cell zinc oxide oxygen vacancy long-term degradation photo-induced effects
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- 작성자박은영
- 작성일2023-01-16
- 652
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Polymorphism and sodium-ion conductivity of NaTa2PO8 synthesized via the Li+/Na+ ion-exchange reaction of LiTa2PO8 by Jaegyeom Kim;Junho Ha;Fouzia Khefif;Jong-Young Kim;Jae-Hwan Pee;Seung-Joo Kim Ceramics International, 2022, 48(14); https://doi.org/10.1016/j.ceramint.2022.04.052 Abstract Ion exchange reaction is a promising method to explore metastable compounds that could not be synthesized by conventional high-temperature solid-phase reactions. Herein, a new sodium tantalum phosphate, NaTa2PO8 was synthesized via the Li+/Na+ ion-exchange reaction of the parent compound, LiTa2PO8 in molten NaNO3 medium. NaTa2PO8 underwent an irreversible phase transition from the low- (LT-NaTa2PO8 to the high-temperature polymorph (HT-NaTa2PO8) at approximately 1000 °C. The crystal structures were solved using an ab initio structural determination method based on synchrotron X-ray powder diffraction data. The LT-NaTa2PO8 presented an orthorhombic structure, closely related to that of the parent LiTa2PO8 structure. In contrast, the HT-NaTa2PO8 was found to adopt a monoclinic structure, belonging to a family of monophosphate tungsten bronzes with pentagonal tunnels. The ionic conductivities of LT-NaTa2PO8 (σ = 5 × 10−5 S/cm at 309 °C) and HT-NaTa2PO8 (σ = 2 × 10−7 S/cm at 300 °C) exhibited Arrhenius behavior with activation energies of 0.49 and 0.79 eV, respectively. Bond valence energy landscape (BVEL) calculations indicated that a three-dimensional (3D) conduction pathway is formed in LT-NaTa2PO8 structure, while the conduction pathway in HT-NaTa2PO8 shows a two-dimensional (2D) character. Keywords Ion-exchangePolymorphismX-ray diffractionIonic conductivity
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14
- 작성자박은영
- 작성일2023-01-16
- 669
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PHF20 is crucial for epigenetic control of starvation-induced autophagy through enhancer activation by Se Won Park;Jaehoon Kim;Sungryong Oh;Jeongyoon Lee;Joowon Cha;Hyun Sik Lee;Keun Il Kim;Daechan Park;Sung Hee Baek Nucleic Acids Research, 2022, 50(14); https://doi.org/10.1093/nar/gkac584 Abstract Autophagy is a catabolic pathway that maintains cellular homeostasis under various stress conditions, including conditions of nutrient deprivation. To elevate autophagic flux to a sufficient level under stress conditions, transcriptional activation of autophagy genes occurs to replenish autophagy components. Thus, the transcriptional and epigenetic control of the genes regulating autophagy is essential for cellular homeostasis. Here, we applied integrated transcriptomic and epigenomic profiling to reveal the roles of plant homeodomain finger protein 20 (PHF20), which is an epigenetic reader possessing methyl binding activity, in controlling the expression of autophagy genes. Phf20 deficiency led to impaired autophagic flux and autophagy gene expression under glucose starvation. Interestingly, the genome-wide characterization of chromatin states by Assay for Transposase-Accessible Chromatin (ATAC)-sequencing revealed that the PHF20-dependent chromatin remodelling occurs in enhancers that are co-occupied by dimethylated lysine 36 on histone H3 (H3K36me2). Importantly, the recognition of H3K36me2 by PHF20 was found to be highly correlated with increased levels of H3K4me1/2 at the enhancer regions. Collectively, these results indicate that PHF20 regulates autophagy genes through enhancer activation via H3K36me2 recognition as an epigenetic reader. Our findings emphasize the importance of nuclear events in the regulation of autophagy.
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- 작성자박은영
- 작성일2023-01-16
- 664
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Orientation-Mediated Luminescence Enhancement and Spin-Orbit Coupling in ZnO Single Crystals by Ali Hassan;Abbas Ahmad Khan;Yeong Hwan Ahn;Muhammad Azam;Muhammad Zubair;Wei Xue;Yu Cao Nanomaterials, 2022, 12(13); https://doi.org/10.1063/5.0092654 Abstract Temperature-, excitation wavelength-, and excitation power-dependent photoluminescence (PL) spectroscopy have been utilized to investigate the orientation-modulated near band edge emission (NBE) and deep level emission (DLE) of ZnO single crystals (SCs). The near-band-edge emission of ZnO SC with orientation exhibits strong and sharp emission intensity with suppressed deep level defects (mostly caused by oxygen vacancies Vo). Furthermore, Raman analysis reveals that orientation has dominant E2 (high) and E2 (low) modes, indicating that this direction has better crystallinity. At low temperature, the neutral donor-to-bound exciton (DoX) transition dominates, regardless of the orientation, according to the temperature-dependent PL spectra. Moreover, free-exciton (FX) transition emerges at higher temperatures in all orientations. The PL intensity dependence on the excitation power has been described in terms of power-law (I~Lα). Our results demonstrate that the α for , , and is (1.148), (1.180), and (1.184) respectively. In short, the comprehensive PL analysis suggests that DoX transitions are dominant in the NBE region, whereas oxygen vacancies (Vo) are the dominant deep levels in ZnO. In addition, the orientation contains fewer Vo-related defects with intense excitonic emission in the near band edge region than other counterparts, even at high temperature (~543 K). These results indicate that growth direction is favorable for fabricating ZnO-based highly efficient optoelectronic devices. Keywords: zinc oxide; single crystal; photoluminescence; exciton; impurities and defects
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- 작성자박은영
- 작성일2023-01-16
- 578
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8
- 작성자박은영
- 작성일2023-01-13
- 619
- 동영상동영상
[논문] 곽원진 - Acceleration of Singlet Oxygen Evolution by Superoxide Dismutase Mimetics in Lithium–Oxygen Batteries. 위치 확인