Ki Ro Yoon

To achieve a high reversibility and long cycle life for lithium-oxygen (Li-O₂) batteries, the irreversible formation of Li₂O₂, inevitable side reactions, and poor charge transport at the cathode interfaces should be overcome. Here, we report a rational design of air cathode using a cobalt nitride (Co₄N) functionalized carbon nanofiber (CNF) membrane as current collector-catalyst integrated air cathode. Brush-like Co₄N nanorods are uniformly

Rational design and massive production of bifunctional catalysts with fast oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics are critical to the realization of highly efficient lithium-oxygen (Li-O2) batteries. Here, we first exploit two types of double-walled RuO2 and Mn2O3 composite fibers, i.e., (i) phase separated RuO2/Mn2O3 fiber-in-tube (RM-FIT) and (ii) multicomposite RuO2/Mn2O3 tube-in-tube (RM-TIT), by controlling ramping rate during electrospinning process. B

Abstract The physical and chemical degradations of a state‐of‐the‐art proton exchange membrane (PEM) composed of a perfluorinated sulfonic acid (PFSA) ionomer and polytetrafluoroethylene (PTFE) reinforcement are induced through the repeated expansion/shrinkage of the ionomer and free radical attacks. Such degradations essentially originate from the loose structure of the materials and the low interactive binding force among the PEM constituents. In this study, the need for simplified design prin

Oxygen-based electrocatalysis is an integral aspect of a clean and sustainable energy conversion/storage system. The development of economic bifunctional electrocatalysts with high activity and durability during reversible reactions remains a great challenge. The tailored porous structure and separately presented active sites for oxygen reduction and oxygen evolution reactions (ORR and OER) without mutual interference are most crucial for achieving desired bifunctional catalysts. Here, we report

The configuration of reinforced composite membrane (RCM), composed of porous polytetrafluoroethylene (PTFE) as a mechanical reinforcement and perfluorosulfonic acid (PFSA) as a proton conductive polymer, has gained a large interest due to its promisingly high performance for polymer electrolyte membrane (PEM) fuel cells. However, the inaccessible polymeric nanocomposites in preparing RCMs are still faced with critical challenges associated with immiscible interactions between hydrophilic sulfona

Electrochemical hydrogen peroxide (H₂O₂) production by the direct two-electron (2e^-) oxygen reduction reaction (ORR) has received much attention as a promising alternative to the industrially developed anthraquinone fabrication process. Transition metal (M) and nitrogen doped carbon (M-N-C, M = Fe or Co) catalysts are known to be active for four electron ORR pathways via two + two electron transfer, where the former is for the ORR and the latter for the peroxide

Synthesis of a co-catalyst functionalized photocatalyst: Ni@NiO-loaded W:BiVO₄ nanofibers (Ni@NiO/W:BiVO₄ NFs) are successfully synthesized as efficient photocatalysts. Ni@NiO/W:BiVO₄ NFs exhibit an excellent photocatalytic water oxidation performance due to a bi-functional co-catalytic effect of Ni@NiO.

Gel polymer electrolyte (GPE) based flexible zinc-air batteries (ZABs) are considered promising power sources for next-generation wearable devices because of their high specific energy density, low cost, high safety, and environmental friendliness. However, the liquid component in GPE is susceptible to evaporation through the air cathode, drastically reducing the cell performance and lifetime. Poly(vinyl alcohol) (PVA) is the most widely adopted ion conductive polymer, but its poor water retenti

The development of efficient bifunctional catalysts for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is a key issue pertaining high performance Li-O2 batteries. Here, we propose a heterogeneous electrocatalyst consisting of LaMnO3 nanofibers (NFs) functionalized with RuO2 nanoparticles (NPs) and non-oxidized graphene nanoflakes (GNFs). The Li-O2 cell employing the tailored catalysts delivers an excellent electrochemical performance, affording significantly reduced disc

Air filtration technology for mitigating pollution due to harmful mixtures of particulate matter (PMs) and yellow dust has been continuously improved. However, significantly small-sized airborne contaminants, such as PM2.5, and toxic gases, including volatile organic compounds (VOCs), remain in the atmosphere and critically affect the human health. Therefore, the development of an integrated filtration system with fast detection and high removal efficiency toward various airborne pollutants with

Abstract Lithium–oxygen (Li–O 2 ) batteries are considered as the most promising candidates owing to their higher theoretical energy density than other energy storage devices. However, the unfavorable structure of the air cathode has become a major cause of low performance for Li–O 2 batteries, limiting their use in practical applications. To deal with this issue, the rational construction of porous air electrodes, where crucial reactions take place, is in high demand. Among the various dimensio

The application of nanofiber (NF) and porous metal-organic framework (MOF) has increasingly attracted attention for the protection of public health. This composite platform provides the physical sieving of particulate matters (PMs) and capturing gases, serving as an outstanding filtering medium with lightweight and multifunctionality. Herein, process design and optimization are performed to produce a multifunctional membrane comprised NFs and MOF particles. Electrospinning/electrospray technique