https://scholarworks.unist.ac.kr/handle/201301/49 2026-05-13T02:02:42Z https://scholarworks.unist.ac.kr/handle/201301/91674 Title: Oxide-based Photoelectrocatalytic Biosynthesis Fuelled by H2O and Microplastics Author(s): Kim, Jinhyun 2026-04-26T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91672 Title: Modulating Interfacial Potential Gradients in Metal-Carbon Catalysts via Phase-Engineering for Lithium-Sulfur Batteries Author(s): Kim, Ji-Oh; Guo, Hengquan; Kim, Seonghee; Park, Jae Bin; Chae, Seongwook; Kwon, Taekyun; Hong, Seungjo; Kim, Byeong Jin; Gonzalez, Guadalupe Arturo De la Garza; Park, Minjoon; Kim, Jae Ho; Li, Oi Lun; Lee, Seung Geol; Lee Jin Hong Abstract: Lithium-sulfur batteries (LSBs) suffer from sluggish sulfur redox kinetics and severe shuttling of lithium polysulfides (LiPSs). Although increasing the active surface area of metal-carbon electrocatalysts improves LiPSs redox kinetics, unlocking further improvements requires enhancing intrinsic catalytic activity of the expanded active sites. Herein, a fundamental investigation is conducted to enhance the catalytic capability of active sites by controlling the crystalline phase of the encapsulated cobalt. Theoretical calculations reveal that modulating the cobalt crystalline phase from HCP to FCC enhances the interfacial potential gradient, which serves as the driving force for electron transfer from cobalt to carbon shell at the metal-carbon interface. Guided by this insight, a deliberate temperature-controlled annealing is conducted to regulate the thermodynamically stable phase of cobalt, while alleviating the structural variations of carbon shells. Comprehensive spectroscopic analyses confirm that this approach modulates the electron band structure of the carbon shell, elevating the valence band maximum and enriching the electronic density near the Fermi level. As a result, F-Co@NC exhibits superior LiPSs redox kinetics and strong LiPSs adsorption capability, which in turn improves the electrochemical performance of LSBs. This work presents a broadly applicable design strategy for advancing metal-carbon electrocatalysts, capable of delivering synergistic effects with previous studies. 2026-02-28T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91659 Title: Dimerized small-molecule acceptors with enhanced crystallinity afford efficient and stable polymer solar cells Author(s): Seo, Soodeok; Song, Xuyao; Bae, Kihyun; Kim, Hye Seung; Lee, Seungjun; Guanchao, Chen; Song, Myoung Hoon; Kim, Yun-Hi; Kim, Bumjoon J. Abstract: High power conversion efficiency (PCE) and long-term stability are essential for the commercialization of polymer solar cells (PSCs). In this work, we develop a series of dimerized small-molecule acceptors (DSMAs) with enhanced crystallinity and electron mobility, achieved through systematic linker engineering using three different benzodithiophene (BDT) derivatives: 1) Dimerized Y-type SMA (DY)-BDT featuring a BDT linker, 2) DY-DTBDT containing a conjugation-extended BDT derivative (dithieno[2,3-d:2 ',3 '-d"]benzo[1,2-b:4,5-b']dithiophene, DTBDT), and 3) DY-DTBDT-Cl featuring chlorinated thiophene side-chains on DTBDT. Among them, DY-DTBDT-Cl shows a higher crystallinity and superior electron mobility compared to other DSMAs. Additionally, DY-DTBDT-Cl shows improved molecular compatibility with PM6 donor compared to Y6-BO SMA and other DSMAs due to the chlorinated BDT linker. Consequently, incorporation of DY-DTBDT-Cl into the binary PM6:Y6-BO blend significantly enhances both the PCE and photostability. The resulting ternary PSCs exhibit a higher PCE (18.65%) compared to that of PM6:Y6-BO (17.81%). Notably, the DY-DTBDT-Cl-containing PSCs retain >80% of initial PCE after 500 h under continuous 1-sun illumination, whereas the PCE of PM6:Y6-BO control decreases below 80% within 20 h. Furthermore, the DY-DTBDT-Cl ternary blend demonstrates enhanced mechanical stability in intrinsically stretchable PSCs, retaining >80% of the initial PCE after 20% strain, whereas PM6:Y6-BO exhibits lower than 80% of initial PCE after 10% strain. This study highlights the importance of linker engineering in optimizing DSMAs, offering a promising strategy for enhancing the performance and long-term stability of PSCs. 2026-05-31T15:00:00Z https://scholarworks.unist.ac.kr/handle/201301/91650 Title: B-Site Engineering in Ruddlesden-Popper Perovskites (A2BO4) for H2O2 Production with 4.85% of Solar-to-Chemical Efficiency Author(s): Cho, Jaewon; Choi, Jun-Yong; Jeong, Eunjae; Yu, Je Min; Kim, Youngchul; Lee, Hyunjoo; Lee, Sang-Goo; Lee, Geunsik; Jang, Ji-Wook; Jo, Wook Abstract: The electrochemical synthesis of hydrogen peroxide (H2O2) via the oxygen reduction reaction (ORR) offers a promising alternative to the anthraquinone process, addressing environmental concerns without requiring expensive hydrogen. However, developing catalysts that selectively promote the two-electron ORR pathway while maintaining stability remains challenging. Here, we report Ruddlesden-Popper (RP) perovskite oxides as efficient catalysts for selective H2O2 production. Among the tested LaSrBO4 compositions (B = Ni, Co, Fe, Mn), LaSrNiO4 (LSN) showed the best two-electron ORR selectivity (similar to 87%) and activity. Integrated into a photovoltaic-electrochemical system, LSN achieved a solar-to-chemical conversion efficiency of 4.85%, producing a H2O2 production rate of 149.2 mu mol cm(-2) h(-1) with good stability over 50 h. Density functional theory calculations attributed this performance to favorable H2O2 formation and desorption kinetics at the Ni B-site. Overall, RP perovskites offer earth-abundant, efficient, and sustainable catalysts for electrochemical H2O2 generation, providing an alternative to carbon- or noble-metal-based systems. 2026-03-31T15:00:00Z