https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/73 2026-03-01T07:26:49Z https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/21471 Title: Science and engineering for non-noble-metal-based electrocatalysts to boost their ORR performance: A critical review Authors: Bhoyate, Sanket D.; Kim, Junyoung; de Souza, Felipe M.; Lin, Jerry; Lee, Eunho; Kumar, Anuj; Gupta, Ram K. Abstract: Metal-air batteries (MABs) and fuel cells (FCs) critically rely on electrocatalytic O2 activation, and O2 reduction reaction (ORR), with noble metal-free materials. However, the inception of their synergist reac-tivity is still unclear due to several electronic and structural limitations. Therefore, the correlation between their science and engineering and their experimental as well as theoretical activity descriptors can pave the way for the development of novel cheap, and efficient catalysts. Moreover, with this frame -work, several volcanic correlations were established, indicating that catalyst activity increases linearly with increasing binding energy of ORR intermediates up to a certain point, but after that, the activity decreases as binding energy increases. The motivation of this review is to highlight (i) recent designs and developments on non-noble-metal-containing electrocatalysts for ORR, (ii) correlations between science and engineering and existing activity descriptors to improve the electrocatalyst's ORR perfor-mance, and (iii) prospects and challenges with non-noble-metal-based electrocatalysts. The "science and engineering" of the electrode materials discussed in this review will aid researchers in selecting and designing ORR electrocatalysts for energy conversion processes.(c) 2022 Elsevier B.V. All rights reserved. 2023-01-01T00:00:00Z https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/21485 Title: In situ-grown Co3S4 sheet-functionalized metal-organic framework via surface engineering as a HER catalyst in alkaline media Authors: Park, Kun Woo; Lee, So Yeon; Moon, Juyoung; An, Hyun Ji; Kim, Dong Hyun; Lee, Chang Soo; Park, Jung Tae Abstract: The development of an appropriate catalyst for the hydrogen evolution reaction (HER) in alkaline media remains challenging. Pt catalysts, which are the most conventional HER catalysts, are prone to corrosion in alkaline media. To overcome this limitation, we developed another transition metal catalyst for the HER in alkaline media. In this study, a Co MOF was grown on a nickel foam substrate in the presence of surfactants via a simple hydrothermal reaction, and the material was sulfurized to Co MOF/Co3S4 sheet in Na2S solution through a chemical bath reaction. The morphology, crystallinity, and composition of Co MOF/Co3S4 sheet were studied by field-emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis. The HER properties in alkaline media were measured by linear sweep voltammetry, electrochemical impedance spectroscopy, and Tafel plot analysis. Cyclic voltammetry was used to determine the electrochemically active surface area (ECSA) using a three-electrode system. The best catalytic performance was observed for P-Co MOF/Co3S4 sheet; it exhibited the lowest overpotential at -10 mA cm(-2) (117.9 mV), the lowest Tafel slope (96 mV dec(-1)), and a high ECSA (57.9 mF cm(-2)). The increased binding energy for cobalt and sulfur and the increased attraction of hydride or protons to evolve hydrogen was attributed to the high catalytic performance in alkaline media. Most importantly, the catalytic performance for the HER did not degrade remarkably even after 24 h of operation. 2022-12-01T00:00:00Z https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/21381 Title: Multifunctional Double-Network Self-Healable Hydrogel and Its Application to Highly Reliable Strain Sensors Authors: Seo, Jungyoon; Oh, Seungtaek; Choi, Giheon; Kim, Hongdeok; Kim, Junyoung; Hwang, Taehoon; Mun, Yongjun; Kim, Chihyeon; Choi, Joonmyung; Kim, Se Hyun; Lee, Eunho; Lee, Hwa Sung Abstract: Self-healable hydrogels present an emerging capability in energy harvesting, drug-release agents, artificial skin, and tissue engineering. Despite the various advantages of hydrogels, their low thermal stability, dehydration resistance, and mechanical properties hinder their practical applications. Herein, we introduced glycerol, 1,2,3,4-butanetetracarboxylic acid (BTCA), and sodium polyacrylate (SPA) into a hydrogel composed of poly(vinyl alcohol) (PVA)/ agarose/borax. This resulted in the fabrication of a dual network hydrogel (DNH) that integrates attractive properties such as self-healing properties induced without physicochemical stimuli, stretch-ability, dehydration resistance, anti-drying capability, or anti-freezing capability. The DNH developed in this study maintains flexibility after storage for 1 h at -20 ? and 77.3% of its original weight after storage at 50 ? for 168 h, indicating its superior anti-freezing capability and water retentivity along with excellent self-healing properties. In addition, by blending carbon nanotubes (CNTs) to impart electrical conductivity, we have demonstrated that the CNT-embedded DNH can be successfully applied as an adhesive conductive medium for a stimulus-sensitive sensing channel of strain sensors, one of the key prospects of wearable electronic skins. In particular, the CNT-embedded DNH-based strain sensor can monitor human motion efficiently when attached to human skin without any skin trouble, even after being attached to the skin for several days. Our study can open an avenue for exploring core conductive adhesive hydrogel materials for next-generation wearable electronic devices. 2022-09-01T00:00:00Z https://scholarworks.bwise.kr/kumoh/handle/2020.sw.kumoh/21385 Title: In situ Shape-Stabilization of n-Octadecane PCM in Alginate Matrix through Formation of Emulsion and Solidification by Ionic Crosslinking Authors: Lee, Seung Han; Chae, Haneul; Kim, Nam Yoon; Min, Byung Gil Abstract: A novel in situ shape-stabilization process of paraffinic phase change material (PCM) in alginate matrix was investigated for the purpose of temperature regulating application. n-Octadecane was selected as a paraffinic PCM because of its adequate thermal transition temperature for applying to human body. As the size control of n-octadecane in polymer matrix less than 10 mu m is a core factor for textile application, oil-in-water (O/W) emulsion of n-octadecane in water were adopted for the size control in shape-stabilization of PCM (SSPCM) in polymer matrix. The micelle size of the PCM emulsion could be controlled in the range of 3-8 mu m through O/W emulsion process with high-speed stirring at 3,000-7,000 rpm and small amount of surfactant. The size of micelles in the emulsion decreased with increasing of homogenizing speed and the amount of surfactant. It was also confirmed that the PCM micelle size was maintained in alginate-PCM hybrid solution that was prepared by mixing the O/W emulsion and aqueous sodium alginate solution. The SSPCM films containing 10-30 wt% of n-octadecane in alginate could be successfully prepared by casting the hybrid solution followed by coagulating the cast film in aq. CaCl2 resulting solidification and insolubilization of alginate through intermolecular ionic crosslinking by Ca2+. It was interesting that the shape of n-octadecane in alginate matrix was not spherical but disk shape parallel to the film surface. It was presumed that the discus-type shape-stabilized form of n-octadecane in alginate matrix was originated by vertical compressive force applied during rapid coagulation of the hybrid solution having very low concentration of sodium alginate (4 wt%). The shape of paraffinic PCM stabilized in polymer matrix through O/W emulsion is expected to be controlled when the other polymeric system with thick concentration. 2022-09-01T00:00:00Z