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Extended X-ray absorption fine structure (EXAFS) of FAPbI_(3) for understanding local structure-stability relation in perovskite solar cells

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Journal of Energy Chemistry 2022年第4期31卷 549-554页

作者： Dong-ho Kang Yong-jun Park Yun-Sung Jeon Nam-Gyu Park School of Chemical Engineering and Center for Antibonding Regulated Crystals Sungkyunkwan UniversitySuwon 16419Korea

Perovskite solar cells (PSCs) employing formamidinium lead iodide (FAPbI_(3)) have shown high ***,operational stability has been issued due to phase instability of α phase FAPbI_(3) at ambient *** precursors in the perovskite precursor solution has been proposed to improve not only power conversion efficiency (PCE) but also device ***,there is a controversial issue on the beneficial effect on PCE and/or stability between excess FAI and excess PbI_(2).We report here extended X-ray absorption fine structure (EXAFS) of FAPbI_(3) to study local structural change and explain the effect of excess precursors on photovoltaic performance and *** films prepared from the precursor solution with excess PbI_(2)shows better stability than those from the one with excess FAI,despite similar PCE.A rapid phase transition from α phase to non-perovskite δ phase is observed from the perovskite film formed by excess ***,the (Pb-I) bond distance evaluated by the Pb L_(III)-edge EXAFS study is increased by excess FAI,which is responsible for the phase transition and poor device *** work can provide important insight into local structure-stability relation in the FAPbI_(3)-based PSCs.

关键词： Extended X-ray absorption fine structure EXAFS Excess precursor Local structure Stability Perovskite solar cells

Prediction of mechanical properties of Al alloys with change of cooling rate

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China Foundry 2012年第4期9卷 381-386页

作者： Quan-Zhi Dong Young-Sire Choi jun-ho hong ho-Young Hwang Dept.of Virtual Engineering University of Science and TechnologyIncheon 406-840Korea e-Design Center Korea Institute of Industrial TechnologyIncheon 406-840Korea

The solidification process significantly affects the mechanical properties and there are lots of factors that affect the solidification *** progress has been made in the research on the effect of solidification on mechanical *** them,the PF(Phase Field) model and CA(Cellular Automata) model are widely used as simulation methods which can predict nucleation and its growth,and the size and morphology of the grains during *** they can give accurate calculation results,it needs too much computational memory and calculation *** it is difficult to apply the simulation to the real production *** this study,a more practical simulation approach which can predict the mechanical properties of real aluminum alloys is proposed,by identifying through experiment the relationship between cooling rate and SDAS(Secondary Dendrite Arm Spacing) and mechanical *** experimentally measured values and the values predicted by simulation have relatively small differences and the mechanical properties of a variety of Al alloys are expected to be predicted before casting through use of the simulation.

关键词： mechanical properties dendrite structure aluminum alloy cooling rate solidification castingsimulation

2D spinel ZnCo_(2)O_(4) microsheet-coated functional separator for promoted redox kinetics and inhibited polysulfide dissolution

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Journal of Energy Chemistry 2021年第4期30卷 468-475页

作者： Jeong Seok Yeon Tae ho Park Young Hun Ko Periyasamy Sivakumar jun Su Kim Youngkywon Kim ho Seok Park School of Chemical Engineering Sungkyunkwan UniversitySuwon 16419Gyeonggi-doRepublic of Korea Advanced Batteries Research Center Korea Electronics Technology InstituteSeongnam 13509Gyeonggi-doRepublic of Korea Department of Health Sciences and Technology Samsung Advanced Institute for Health Sciences and Technology(SAIHST)Sungkyunkwan UniversitySuwon 16419Gyeonggi-doRepublic of Korea Department of Chemistry Dongguk University-Seoul CampusJung-gu 04620 SeoulRepublic of Korea

Lithium-sulfur(Li-S)batteries are receiving increasing attention as one of the potential next-generation batteries,owing to their high energy densities and low ***,practical Li-S batteries with high energy densities are extremely hindered by the sulfur loss,low Coulombic efficiency,and short cycling life originating from the polysulfide(LiPS)*** this study,two-dimensional(2D)ZnCo_(2)O_(4) microsheets fabricated by a facile hydrothermal process are employed to modify the separator,for improving the electrochemical performances of Li-S *** resulting 2D Zn Co_(2)O_(4)-coated separator features a coating thickness of approximately 10 lm,high ionic conductivity of 1.8 m S/cm,and low mass loading of 0.2 mg/cm^(2).This 2D ZnCo_(2)O_(4)-coated separator effectively inhibits Li PS shuttle by a strong chemical interaction with Li PS as well as promotes the redox kinetics by Zn CO2O4-coated layers,as determined by X-ray photoelectron spectroscopy analysis,self-discharge,time-dependent permeation test,Li symmetric cell test,and Li2S nucleation ***,the Li-S batteries based on the 2D Zn Co_(2)O_(4)-coated separator exhibit a high initial discharge capacity of 1292.2 m Ah/g at 0.1 ***,they exhibit excellent long cycle stability at 1 and 2 C with capacity retention of 84%and 86%even after800 cycles,corresponding to a capacity fading rate of 0.020%and 0.016%per cycle,***,these Li-S cells with a high sulfur loading at 5.3 mg/cm^(2) and low electrolyte concentration of 9 l L/mg deliver a high discharge capacity of 4.99 m Ah/cm^(2) after 200 cycles at 0.1 C.

关键词： Lithium sulfur batteries Functional separator 2D microsheet Polysulfide Redox kinetics

High-temperature Oxidation Behavior of Zircaloy-4 and Zirlo in Steam Ambient

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Journal of Materials Science & Technology 2010年第9期26卷 827-832页

作者： Hyung hoon Kim jun ho Kim Jin Young Moon ho Seong Lee Jeong Joo Kim Young Suck Chai School of Materials Science and Engineering Kyungpook National University School of Mechanical Engineering Yeungnam University214-1 Dae-dongGyeongsan-si

The oxidation characteristics for Zircaloy-4 and Zirlo in the temperature range of 700-1200°C under steam supply condition were investigated by using a modified thermo-gravimetric *** specimens were oxidized for 3600 s at each temperature and then quenched in a *** oxidation rate constants were measured from the weight gains to evaluate the oxidation behavior in Zircaloy-4 and *** weight gain rates of Zirlo were lower than those of Zircaloy-4,leading to the low rate *** different oxidation behaviors between both cladding materials were considered to be due to the difference in their chemical compositions.

关键词： Zircaloy-4 Zirlo Oxidation

Effect of Palladium Nanoparticles on Photocatalytic Characteristics of N doped Titania Catalyst

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Journal of Materials Science & Technology 2015年第6期31卷 664-669页

作者： Jong-ho Lee Jeong-Il Youn Young-Jig Kim Han-jun Oh Department of Chemistry Hanseo University School of Advanced Materials Engineering Sungkyunkwan University Department of Materials Science Hanseo University

To improve the photocatalytic efficiency of TiO2nanotubular catalyst,N doped and Pd decorated titania nanotubes was successfully synthesized via anodizing,hydrazine hydrate treatment and photoreduction of Pd *** small Pd nanoparticles were precipitated on TiO2nanotubes through photoreduction of Pd ions,and its distribution is relatively *** X-ray photoelectron spectrometry（XPS） result,the N 1s spectrum represents two peaks with binding energy at 399.7 and 400.7 eV,which suggests that the nitrogen elements doped by hydrazine hydrate treatment are located in interstitial sites of the TiO2crystalline *** N doped TiO2nanotubes with Pd particles,a high photocurrent was detected due to increase of interface charge carrier separation ***,N doped and Pd decorated TiO2nanotubes exhibited much higher dye destruction efficiency and rate constant due to the synergistic effect of the N dopant and the Pd deposition on TiO2nanotubes.

关键词： Pd nanoparticle Titania nanotube Anodizing Dye dec

Study on SCR De NO_x mechanism through in situ electrical conductivity measurements on V_2O_5-WO_3/TiO_2 catalysts

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Rare Metals 2006年第z2期25卷 77-83页

作者： HA Heon Phil junG Soon Hyo LEE jun Yub hoNG Sung ho Metal Processing Research Center Korea Institute of Science and Technology Cheongryang Seoul 130-650 Republic of Korea Power Engineering Research Institute Korea Power Engineering Company Inc. 360-9 Mabuk-ri Guseong-eup Yongin-si Gyeonggi-do 449-713 Republic of Korea

V2O5-WO3/TiO2 catalysts were prepared by impregnation method and in situ electrical conductivity measurements were carried out to investigate the reaction mechanism for ammonia SCR (selective catalytic reduction) of NOx. The electrical conductivity change with ammonia supply and the increase of electrical conductivity were mainly caused by reduction of the labile surface oxygen. The electrical conductivity change of catalysts shows close relationship with the conversion rate of NOx. Variation of conversion rate in atmosphere without gaseous oxygen also supports that the labile lattice oxygen is indispensable in the initial stage of the de NOx reaction. These results suggest that the liable lattice oxygen acts decisive role in the de NOx mechanism. They also support that De NOx reaction occurs through the Eley-Rideal type mechanism. The amount of labile oxygen can be estimated from the measurement of electrical conductivity change for catalysts with ammonia supply.

关键词： De NOx selective catalytic reduction electrical conductivity lattice oxygen

UV-assisted flash light welding process to fabricate silver nanowire/graphene on a PET substrate for transparent electrodes

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Nano Research 2018年第4期11卷 2190-2203页

作者： Wan-ho Chung Sung-Hyeon Park Sung-jun Joo Hak-Sung Kim Department of Mechanical Engineering Hanyang University 17 Haendang-Dong Seongdong-Gu Seoul 133-791 Republic of Korea Institute of Nano Science and Technology Hanyang University Seou1133-791 Republic of Korea

Graphene oxide and silver nanowires were bar coated onto polyethylene terephthalate （PET） substrates and then welded using an ultraviolet （UV）-assisted flash light irradiation process to achieve both high electrical conductivity and low haze. The irradiation process connected adjacent silver nanowires by welding, while simultaneously reducing the graphene oxide to graphene. This process was performed using a custom W-assisted flash light welding system at room temperature under ambient conditions and was extremely rapid, with processing time of several milliseconds. The effects of varying the weight fractions of the silver nanowires and graphene oxide and of varying the W-assisted flash light welding conditions （light energy and pulse duration） were investigated. The surface morphologies of the welded silver nanowire/graphene films were analyzed using scanning electron microscopy. Optical characterizations, including transmittance and haze measurements, were also conducted using a spectrophotometer. To test their resistance to oxidation, the welded silver nanowire/graphene films were subjected to high temperature in a furnace （100 ℃）, and their sheet resistances were measured every hour. The flash light welding process was found to yield silver nanowire/graphene films with high oxidation resistance, high conductivity （14.35 Ω·sq-1）, high transmittance （93.46%）, and low haze （0.9%）. This material showed uniform temperature distribution when applied as a resistive heating film.

关键词： silver nanowires graphene oxide transparent electrode flash light welding printed electronics

The photocatalytic ·OH production activity of g-C_(3)N_(4) improved by the introduction of NO

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Chinese Chemical Letters 2022年第10期33卷 4715-4718页

作者： jun Jing Kai Qi Guohui Dong Mengmeng Wang Wingkei ho School of Environmental Science and Engineering Shaanxi University of Science and TechnologyXi'an 710021China Department of Science and Environmental Studies and Centre for Education in Environmental Sustainability The Education University of Hong KongHong KongChina

The efficiency of photocatalytic pollutant removal largely depends on the ability of the photocatalytic system to produce hydroxyl radicals(·OH).however,the capability of photocatalyst to produce·OH is not strong at *** the capacity of photocatalytic system to produce·OH has always been a tough problem and challenge in the field of environmental *** this research,it was found that introducing nitric oxide(NO)into the graphitic carbon nitride(g-C_(3)N_(4))photocatalytic system could memorably enhance the ability of producing·OH *** study provides a new idea for improving the capacity of photocatalytic·OH production.

关键词： Active oxygen species Nitrogen oxide Photocatalysis Organic pollution g-C_(3)N_(4)

Development of vehicle-recognition method on water surfaces using LiDAR data:SPD^(2)(spherically stratified point projection with diameter and distance)

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Defence Technology（防务技术） 2024年第6期36卷 95-104页

作者： Eon-ho Lee Hyeon jun Jeon Jinwoo Choi Hyun-Taek Choi Sejin Lee The Department of Mechanical Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea Ocean System Engineering Research Division Korea Research Institute of Ships and Ocean Engineering(KRISO)Daejeon 34103Republic of Korea The Division of Mechanical&Automotive Engineering Kongju National University1223-24 Cheonan-daeroCheonan 31080Republic of Korea

Swarm robot systems are an important application of autonomous unmanned surface vehicles on water *** monitoring natural environments and conducting security activities within a certain range using a surface vehicle,the swarm robot system is more efficient than the operation of a single object as the former can reduce cost and save *** is necessary to detect adjacent surface obstacles robustly to operate a cluster of unmanned surface *** this purpose,a LiDAR(light detection and ranging)sensor is used as it can simultaneously obtain 3D information for all directions,relatively robustly and accurately,irrespective of the surrounding environmental *** the GPS(global-positioning-system)error range exists,obtaining measurements of the surface-vessel position can still ensure stability during platoon *** this study,a three-layer convolutional neural network is applied to classify types of surface *** aim of this approach is to redefine the sparse 3D point cloud data as 2D image data with a connotative meaning and subsequently utilize this transformed data for object classification ***,we have proposed a descriptor that converts the 3D point cloud data into 2D image *** use this descriptor effectively,it is necessary to perform a clustering operation that separates the point clouds for each *** developed voxel-based clustering for the point cloud ***,using the descriptor,3D point cloud data can be converted into a 2D feature image,and the converted 2D image is provided as an input value to the *** intend to verify the validity of the proposed 3D point cloud feature descriptor by using experimental data in the ***,we explore the feasibility of real-time object classification within this framework.

关键词： Object classification Clustering 3D point cloud data LiDAR(light detection and ranging) Surface vehicle