Search

Your search keyword '"Shim, Sang Eun"' showing total 551 results
Start Over Author "Shim, Sang Eun"
551 results on '"Shim, Sang Eun"'

155. Effect of Initiator on Performance of Polyvinylacetate as Emulsion Adhesive

Author

Shim Sang Eun

Subjects
Materials science, Chain-growth polymerization, Polymerization, Bulk polymerization, Polymer chemistry, technology, industry, and agriculture, Precipitation polymerization, Emulsion polymerization, Chain transfer, macromolecular substances, Ionic polymerization, Polymer engineering
Abstract

Polyvinylacetate (PVAc) was prepared using thermal initiation and redox initiation via emulsion polymerization at 80 o C. The polymerization conditions had a significant effect on the properties of the synthesized PVAc. When hydrogen peroxide and tartaric acid as the initiator for redox polymerization were used, the synthesized PVAc had a low molecular weight. In comparison with thermal polymerization, smaller PVAc particles were formed during the redox polymerization due to relatively faster polymerization rate, which in turn resulted in improved adhesion property. It is considered that the rapid generation of smaller particles induces the formation of a large surface area.

Published
2015
Full Text
View/download PDF

156. 전자빔 조사에 따른 PEMFC용 Pt/C 촉매의 활성 및 내구성 변화

Author

이병철 ( Byung Cheol Lee ), Won Jun Jo, 황혜인 ( Hye In Hwang ), Baeck Sung Hyeon, 최민철 ( Min Cheol Choi ), 임동욱 ( Dong Wook Lim ), and Shim Sang Eun

Subjects
Materials science, Chemical engineering, Modeling and Simulation, Electrode, Metals and Alloys, Electron beam processing, Proton exchange membrane fuel cell, E beam irradiation, Durability, Pt c catalyst, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials
Published
2015
Full Text
View/download PDF

178. A Graphene Oxide Nanosheet Supported NHC–Palladium Complex as a Highly Efficient and Recyclable Suzuki Coupling Catalyst.

Author

Qian, Yingjie, So, Jaeil, Jung, Sang-Yung, Hwang, Sosan, Jin, Myung-Jong, and Shim, Sang Eun

Subjects
SUZUKI reaction, GRAPHENE oxide, HETEROGENEOUS catalysts, SURFACE analysis, X-ray photoelectron spectroscopy, OXYGEN reduction
Abstract

A practical heterogeneous catalyst was prepared by anchoring a triazine-tethered N-heterocyclic carbene (NHC)–palladium complex on the surface of graphene oxide (GO) nanosheets. The immobilized complex was characterized by X-ray photoelectron spectroscopy, field-emission transmission electron microscopy, energy-dispersive X-ray spectroscopy, and surface area analysis. It proved to be a highly active and durable heterogeneous catalyst for Suzuki coupling reactions. At room temperature, the use of this catalyst enabled the preparation of various biaryls and heterobiaryls in short reaction times. The catalytic system could be recycled at least 10 times with almost consistent activity. The results reveal that the stable palladium complex is strongly anchored on the surface of GO nanosheets. Interestingly, an open planar network of the GO nanosheet support plays a role during the catalytic process in enhancing the catalytic activity. [ABSTRACT FROM AUTHOR]

Published
2019
Full Text
View/download PDF

194. Synergistic effect of heterointerface engineering and oxygen vacancy in CoFe-layered double hydroxide/Co3O4composite for boosting alkaline water oxidation

Author

Lee, Jaeseo, Min, Kyeongseok, Son, Yujin, Ko, Dasol, Shim, Sang Eun, and Baeck, Sung-Hyeon

Abstract

Developing highly active and cost-efficient electrocatalyst for the oxygen evolution reaction (OER) is crucial for practical water electrolysis, which is an ideal technique for obtaining high-purity hydrogen without causing environmental pollution. In this study, we propose a composite material of bimetallic CoFe-layered double hydroxide (LDH) and oxygen vacancy-rich Co3O4on carbon support (CoFe-LDH/Vo-Co3O4@C), which is synthesized using co-precipitation, thermal treatment, and facile ultrasonic treatment methods. By efficiently modulating surface electronic structure and introducing abundant structural defect sites, the CoFe-LDH/Vo-Co3O4@C exhibits remarkable OER activity and long-term stability. Specifically, the CoFe-LDH/Vo-Co3O4@C has a low overpotential of 296 mV to achieve a current density of 10 mA cm−2, and a very small Tafel slope of 60.2 mV dec−1, which are much superior values than those of the precious metal-based RuO2(331 mV and 73.7 mV dec−1). Furthermore, the excellent electrocatalytic durability of the CoFe-LDH/Vo-Co3O4@C for over 100 h in alkaline solution suggests its potential for industrial applications of water electrolysis.

Published
2023
Full Text
View/download PDF

Catalog

Books, media, physical & digital resources
See catalog results