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Thermal catalytic device for toluene decomposition via direct heating
Hyeonjin Eom,Seunghwan Ahn,Na Kyong Kim,Hyun Wook Kang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
A thermal catalytic device that reduces the energy required for the catalytic oxidation of volatile organic compounds (VOCs) was developed. The catalytic oxidation of VOCs is typically performed under indirect heating conditions resulting in high energy consumption. The proposed device drastically decreases the energy consumed and increases the amount of toluene decomposed during catalytic oxidation because the catalysts are heated directly via a carbon nanotube (CNT) element. The proposed device consists of a glass-fiber textile coated in CNTs, α-MnO₂ nanostructures, and Pt nanostructures. The effect of different α-MnO₂ nanostructures (granular and urchin-like) on device performance was investigated. Moreover, the effect of each device component on the toluene decomposition efficiency and energy consumption of the device was explored by determining the toluene concentration of gaseous toluene after the catalytic oxidation process and the associated energy consumption. The device featuring urchin-like α-MnO₂ nanostructures coated in a thin layer of Pt achieves higher toluene decomposition efficiency than the device featuring granular α-MnO₂ nanostructures coated in Pt nanoparticles. Moreover, the device featuring urchin-like α-MnO₂ nanostructures coated in a thin Pt layer achieves higher toluene decomposition efficiency and lower energy consumption under direct heating conditions than under conventional indirect heating conditions.
Eom, Hyeonjin,Kim, Jae-Han,Hur, Junyoung,Kim, Taek-Soo,Sung, Sang-Keun,Choi, Jun-Hyuk,Lee, Eungsug,Jeong, Jun-Ho,Park, Inkyu American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.45
<P>Metal thin film electrodes on flexible polymer substrates are inherently unstable against humidity and mechanical stresses because of their poor adhesion properties. We introduce a novel approach for improving the adhesion characteristics of metal–polymer interface based on the nanostructuring of the polymer substrate by using nanoimprint lithography. The adhesion characteristics of metal–polymer interface were measured by accelerated test, cyclic bending test and double cantilever beam (DCB) test. The interface of Au/Ti dual layer thin film and nanoimprinted PMMA substrate shows over 2.03 and 1.95 times higher adhesion energy (<I>G</I><SUB>c</SUB>) than that of Au/Ti dual layer thin film and plane PMMA substrate in air and wet environments, respectively. The adhesion energy between metal thin film and polymer substrate was dramatically improved by the increased surface roughness and mechanical interlocking effect of numerous nanoscale anchors at the edges of nanoimprinted surface, which was verified by both experiment and numerical analysis.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-45/acsami.5b06631/production/images/medium/am-2015-06631q_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b06631'>ACS Electronic Supporting Info</A></P>
Electrodeposition of Silver-Nickel Thin Films with a Galvanostatic Method
Eom, Hyeonjin,Jeon, Byungjun,Kim, Donguk,Yoo, Bongyoung The Japan Institute of Metals 2010 Materials Transactions Vol.51 No.10
<P>NiAg thin films were deposited by galvanostatic electrodeposition in an electrolyte containing NiSO<SUB>4</SUB>, AgNO<SUB>3</SUB> and C<SUB>6</SUB>H<SUB>5</SUB>Na<SUB>3</SUB>O<SUB>7</SUB>. The variation of composition and crystallography of electrodeposited NiAg thin films with current density and electrolyte concentration was investigated. At a low current density, electrodeposition of silver was dominant, which could be induced by a comparably low reduction potential. However, nickel electrodeposition became the dominant component at a higher current density because of the mass transfer limitation of Ag ions. When 50 mA/cm<SUP>2</SUP> was applied, the FCC (200) phase was observed, which implies significant enhancement of the nucleation rate by increasing the reduction potential at a high current density condition.</P>
Joule Heating of Metallic Nanowire Random Network for Transparent Heater Applications
( Aekachan Pichitpajongkit ),( Hyeonjin Eom ),( Inkyu Park ) 한국센서학회 2020 센서학회지 Vol.29 No.4
Silver nanowire random networks are promising candidates for replacing indium tin oxide (ITO) as transparent and conductive electrodes. They can also be used as transparent heating films with self-cleaning and defogging properties. By virtue of the Joule heating effect, silver nanowire random networks can be heated when voltage bias is applied; however, they are unsuitable for long-term use. In this work, we study the Joule heating of silver nanowire random networks embedded in polymers. Silver nanowire random networks embedded in polymers exhibit breakdown under the application of electric current. Their surface morphological changes indicate that nanoparticle formation may be the main cause of this electrical breakdown. Numerical analyses are used to investigate the temperatures of the silver nanowire and substrate.
Kwon, Jinhyeong,Cho, Hyunmin,Eom, Hyeonjin,Lee, Habeom,Suh, Young Duk,Moon, Hyunjin,Shin, Jaeho,Hong, Sukjoon,Ko, Seung Hwan American Chemical Society 2016 ACS APPLIED MATERIALS & INTERFACES Vol.8 No.18
<P>Copper nanomaterials suffer from severe oxidation problem despite the huge cost effectiveness. The effect of two different processes for conventional tube furnace heating and selective laser sintering on copper nanoparticle paste is compared in the aspects of chemical, electrical and surface morphology. The thermal behavior of the copper thin films by furnace and laser is compared by SEM, XRD, FT-IR, and XPS analysis. The selective laser sintering process ensures glow annealing temperature, fast processing speed with remarkable oxidation suppression even in air environment while conventional tube furnace heating experiences moderate oxidation even in Ar environment. Moreover, the laser-sintered copper nanoparticle thin film shows good electrical property and reduced oxidation than conventional thermal heating process. Consequently, the proposed selective laser sintering process can be compatible with plastic substrate for copper based flexible electronics applications.</P>
Effect of surface charge density on electret filters charge degradation by organic solvent exposure
Woo Jin Lee,Han Bin Kim,Hyeonjin Eom,Jungho Hwang,Myong-Hwa Lee 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.1
The effect of the surface charge density of an electret filter on its collection efficiency degradation via isopropyl alcohol (IPA) species exposure is discussed in this study. Five electret filters with different electrostatic properties and identical physical properties were prepared and exposed to IPA species. Furthermore, the filtration performance was evaluated. Filters exposed to IPA droplets showed a drastic reduction in the collection efficiency. In addition, the electret filter with a higher surface charge density had a higher tolerance to IPA droplets, that is, the challenged IPA droplet amount that neutralized the electret filter with a high surface charge density (= 5.0 × 10<SUP>-5</SUP> C/㎡) was 2.5 times higher than that of an electret filter with a low surface charge density (= 1.9 × 10<SUP>-5</SUP> C/㎡). The results of this study revealed that there was a positive relationship between the surface charge density and challenged amount required to neutralize an electret filter.