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- 검색키워드
- 저자 : Gwanwon Lee (검색결과 3 건)
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Gwanwon Lee,Min Eui Lee,Sung-Soo Kim,Han-Ik Joh,Sungho Lee 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.105 No.-
We demonstrate the conversion of disposable polypropylene (PP) masks into non-graphitizable carbonpowders that can be applied as anode materials in sodium ion batteries. Sulfuric acid treatment and subsequentpyrolysis of the masks resulted in polyaromatic and carbon structures, respectively. Fouriertransforminfrared, Raman, and X-ray photoelectron spectroscopies revealed that a longer sulfuric acidtreatment time results in a higher carbon yield (up to 50%), indicating that the infusible structures generatedduring sulfonation played a critical role in the development of the resulting carbon. In addition, weconfirmed the detailed mechanism by NMR analysis, which indicated that sulfonation induced not onlysimple cross-linking but also polyaromatic hydrocarbons, contributing to distinct D and G bands in theRaman spectra. However, even heat-treatment at a high temperature of 2400 C could not facilitate a graphiticstructure, implying that PP is intrinsically non-graphitizable. Finally, we used mask-derived carbonas an anode material of sodium ion batteries. The prepared hard carbon anode showed a high reversiblecapacity of 340 mA h/g at a current rate of 0.01 A/g, and 53% of the capacity was maintained at 100times higher current rate, suggesting the superior rate capability. In addition, the assembled full cellachieved a reversible capacity of 110 mA h/g with a high energy density of 352 Wh/kg, validatingthe feasibility of its application as an anode material of sodium ion batteries. The solid-to-solid conversionof PP-based masks to carbons could contribute to the upcycling technology as one of the potentiallyaffordable waste plastic management techniques.
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Hae Ri Lee,Seunggyun Han,Jong Yoon Lee,Gwanwon Lee,Sungho Lee,Han-Ik Joh 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-
Heteroatom-doped carbon catalysts are promising alternatives to platinum group metal-free catalysts foroxygen reduction reaction (ORR). To enhance the ORR activity of carbon-based catalysts, the break ofelectroneutrality and number of active sites must be maximized. In this study, an annealing process ata mild temperature was introduced before heteroatom doping to control the content and configurationof the oxygen functional groups on the graphene oxide (GO). Pre-annealing affects the chemical configurationand the porosity of GO such that the epoxy groups are converted into carbonyl groups accompanyingthe defect formation. Interestingly, The carbonyl-enriched environment allowed ammonia borane,as a dopant with nitrogen and boron atoms, the enhanced doping performance, inducing the formation ofhigher number of heteroatom doping sites and additional defects in the graphene lattice. The aBNG-150catalyst demonstrated outstanding ORR activity in both half- and single-cell evaluations because it hadthe highest heteroatom content and meso/macropores derived from the elimination of oxygen functionalgroups, which can facilitate ORR catalytic activity and O2 diffusion pathway. Therefore, we believe thatthis approach provides an effective route for synthesizing carbon-based catalysts with remarkable ORRperformances.
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Gwanwon Lee,Seong In Park,신훈이,조한익,김성수,이성호 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.122 No.-
Polystyrene (PS) was chemically treated with sulfuric acid to prepare stabilized precursors, which wereconverted into carbonaceous materials with high yield via subsequent carbonization. In addition to sulfuricacid, paraformaldehyde (PFA) was used to increase the crosslink density within the sulfonated PSchain networks by forming methylene bridges between phenyl rings via condensation. This transformedPS into a black glassy powder with increased crosslinking points. The carbon yield of the stabilized PSobtained after carbonization showed was considerably higher (45.3 wt%) than those of pristine PS(0 wt%) and sulfonated PS without PFA (22.4 wt%). This was attributed to its superior degree of crosslinksand the additional contribution of sulfur bridges to its thermal stability during carbonization. Furtherthermal treatment up to 2800 C resulted in the formation of an intermediate structure between hardand soft carbons, which was directly revealed by microscopic images. These simultaneous reactions ofsulfonation and condensation can be universally applied to various PS wastes, regardless of their shapeand morphology. This suggests that the solid-to-solid transformation from PS to carbonaceous substancescan be an effective and affordable method of upcycling general PS wastes.
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