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Nano Materials Science 2024年第2期6卷 223-234页

作者： Nisa Nashrah Abdelkarim Chaouiki Wail Al Zoubi young gun ko Integrated Materials Chemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan38541Republic of Korea

The trade-off between efficiency and stability has limited the application of TiO_(2)as a catalyst due to its poor surface ***,we present a modification of a TiO_(2)layer with highly stable Sub-5 nm Fe_(2)O_(3)nanoparticles(NP)by modulating its structure-surface reactivity relationship to attain efficiency-stability balance via a voltage-assisted oxidation *** situ simultaneous oxidation of the Ti substrate and Fe precursor using high-energy plasma driven by high voltage resulted in uniform distribution of Fe_(2)O_(3)NP embedded within porous TiO_(2)*** surface characterizations with density functional theory demonstrated an improved electronic transition in TiO_(2)due to the presence of surface defects from reactive oxygen species and possible charge transfer from Ti to Fe;it also unexpectedly increased the active site in the TiO_(2)layer due to uncoordinated electrons in Sub-5 nm Fe_(2)O_(3)NP/TiO_(2)catalyst,thereby enhancing the adsorption of chemical functional groups on the *** unique embedded structure exhibited remarkable improvement in reducing 4-nitrophenol to 4-aminophenol,achieving approximately 99%efficiency in 20 min without stability decay after 20 consecutive cycles,outperforming previously reported TiO_(2)-based *** finding proposes a modified-electrochemical strategy enabling facile construction of TiO_(2)with nanoscale oxides extandable to other metal oxide systems.

关键词： Titanium dioxide Oxide nanoparticle Electrochemical oxidation Surface reactivity Efficiency Stability

Nucleation and growth behavior of coating film on Mg–Al–Zn alloy with different surface topographies via plasma electrolytic oxidation

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Journal of Magnesium and Alloys 2022年第8期10卷 2185-2192页

作者： Nisa Nashrah Sung Hun Baek young gun ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea

This work was made to investigate how nucleation and growth behavior of the coating film were affected by surface topographies of Mg–Al–Zn alloy substrate during the initial stage of plasma electrolytic oxidation(PEO).To satisfy this end,a single substrate was prepared by mechanical treatment exhibiting rough and smooth regions with an equal area on the *** rough region with prominent hills and grooves induced the breakdown of passive film,which was indicated by an early appearance of plasma discharge on the rough region since nucleation of coating film occurred preferentially around the ***,the coating film grown on the grooves was somewhat thicker and more porous than the film grown on the hills and smooth *** was due to the fact that the growth of the coating film was found to be localized in the presence of rough region,which was in line with the discharge ***,the nucleation and growth behavior during the initial stage of PEO will be discussed schematically on the basis of microstructural interpretation.

关键词： Mg alloy Surface roughness Plasma electrolytic oxidation Coating film

Advanced prediction of organic–metal interactions through DFT study and electrochemical displacement approach

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Journal of Magnesium and Alloys 2023年第1期11卷 301-316页

作者： Abdelkarim Chaouiki Wail Al Zoubi young gun ko Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541South Korea

Heterocyclic compounds are the promising biological compounds as nature-friendly for the corrosion protection of metallic *** this work,three heterocyclic compounds such as 1-azanaphthalene-8-ol(8-AN),2-methylquinoline-8-ol(8-MQ),and 8-quinolinol-5-sulfonic acid(8-QSA)were used as green compounds,and their anti-corrosion performance for AZ31 Mg in saline water was discussed on the basis of impedance interpretation and surface *** found that the electrochemical performance was improved in the order of 8-AN>8-MQ>8-QSA,demonstrating the electron donor effect of N-heterocycles to form coordination complexes on the magnesium *** the electrochemical performance,the protective layer constructed at the optimal concentration reinforces the barrier against aggressive environments,with potential inhibition efficiency of 87.4%,99.0%,and 99.9%for 8-QSA,8-MQ,and 8-AN,*** chemical parameters and electron density distribution for free organic species in the absence and presence of Mg^(2+)cation were evaluated using density functional theory(DFT).Upon the formation of coordination complexes between organic compound and Mg^(2+),energy gap underwent change about ΔE=5.7 eV in the 8-AN/Mg^(2+)***,the adsorption of heterocyclic compounds on Mg surface reveals the formation of strong covalent bonds with Mg atoms,which further confirmed by the electron density difference and projected density of states *** on theoretical calculations,three inhibitors can adsorb on the metal surface in both parallel and perpendicular orientations via C,O and N *** the parallel configuration,the C-Mg,N-Mg and O-Mg bond distances are between 2.11 and 2.25˚A,whereas the distances in the case of perpendicular adsorption are between 2.20 and 2.40˚A(covalent bonds via O and N atoms).The results indicated that parallel configurations are energetically more stable,in which the adsorption energies are-4.48 eV(8-AN),-4.28 eV(8-MQ)and-3.82 e

关键词： Organic layer Heterocyclic compounds Electrochemical behavior DFT modeling

Fabrication of branch-like Aph@LDH-MgO material through organic-inorganic hybrid conjugation for excellent anti-corrosion performance

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镁合金学报(英文) 2023年第7期11卷 2469-2485页

作者： Maryam Chafiq Abdelkarim Chaouiki Rachid Salghi young gun ko Materials Electrochemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea Laboratory of Applied Chemistry and Environment ENSAUniversity Ibn ZohrPO Box 1136Agadir80000Morocco

Layered double hydroxides(LDH)frameworks have shown significant enhancement in stability and reusability,and their tailorable architecture brings new insight into the development of the next generation of hybrid materials,which attracted considerable attention in many fields over the *** of the factors contributing to the widespread applicability of layered double hydroxides is their adaptable composition,which can accommodate a wide spectrum of potential anionic *** exceptional property makes the LDH system simple to adjust for various ***,most LDH systems are synthesized in situ in an autoclave at high temperatures and pressures that severely restrict the industrial use of such coating *** this study,LDH was directly synthesized on a magnesium alloy that had undergone plasma electrolytic oxidation(PEO)treatment in the presence of ethylenediaminetetraacetic acid,thereby avoiding the use of hydrothermal autoclave *** LDH system was compared with a hybrid architecture consisting of organic-inorganic *** organic layer was fabricated on top of the LDH film using 4-Aminophenol(Aph)compound,resulting in a smart hierarchical structure that can provide a robust Aph@LDH film with excellent anti-corrosion *** the molecular level,the conjugation characteristics and adsorption mechanism of Aph molecule were studied using two levels of theory as ***,Localized orbit locator(LOL)-πisosurface,electrostatic potential(ESP)distribution,and average local ionization energy(ALIE)on the molecular surface were used to highlight localization region,reveal the favorable electrophilic and nucleophilic attacks,and clearly explore the type of interactions that occurred around interesting ***,first-principles based on density functional theory(DFT)was applied to study the hybrid mechanism of Aph on LDH system and elucidate their mutual *** experimental and computational analyses suggest t

关键词： Magnesium alloy Surface modification LDH Organic-inorganic hybrid materials Inter-/intra-molecular interactions

Electrochemical response of MgO/Co_(3)O_(4) oxide layers produced by plasma electrolytic oxidation and post treatment using cobalt nitrate

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Journal of Magnesium and Alloys 2023年第3期11卷 1057-1073页

作者： Mosab Kaseem Tehseen Zehra Tassawar Hussain young gun ko Arash Fattah-alhosseini Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea Department of Materials Engineering Bu-Ali Sina UniversityHamedan 65178-38695Iran

This work looked into the influence of the sealing treatment on the structural feature and electrochemical response of AZ31 Mg alloy coated via plasma electrolytic oxidation(PEO).Here,the inorganic layers produced by PEO in an alkaline-phosphate electrolyte were subsequently immersed for different periods in cold(60°C)and hot(100°C)aqueous solutions containing either 1 or 3 gr of cobalt nitrate hexahydrate in the presence of hydrogen peroxide as an *** results showed that the sealing treatments in the hot solutions could trigger the hydration reactions of PEO coating which would largely assist the surface incorporation of Co_(3)O_(4)into the *** contrast,the sealing in cold solutions led to less compact coatings,which was attributed to the fact the hydration reactions would be restricted at 60°C.A nearly fully sealed coating with a porosity of~0.5%was successfully formed on the sample immersed in the hot solution containing 1 gr of cobalt nitrate ***,the electrochemical stability of this fully sealed coating was superior to the other samples as it had the lowest corrosion current density(4.71×10^(-10)A·cm^(-2))and the highest outer layer resistance(3.81×10^(7)Ω·cm^(2)).The composite coatings developed in this study are ideal for applications requiring high electrochemical stability.

关键词： AZ31 Mg alloy Plasma electrolytic oxidation Co_(3)O_(4) Hydration Corrosion

Effect of Deformation Temperature on Microstructure and Mechanical Properties of AZ31 Mg Alloy Processed by Differential-Speed Rolling

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Journal of Materials Science & Technology 2015年第5期31卷 498-503页

作者： Mosab Kaseem Bong Kwon Chung Hae Woong Yang kotiba Hamad young gun ko School of Materials Science and Engineering Yeungnam University

A differential-speed rolling(DSR) was applied to AZ31 magnesium alloy sample at different rolling temperatures of 473,523,573,and 623 K with 1-pass and 2-pass *** microstructural evolution and mechanical properties of the deformed samples were *** rolling temperature was found to be an important parameter affecting the microstructural *** DSR at 473 K,the microstructure was more homogeneous than that obtained after deformation by equal-speed rolling(ESR).The fully recrystallized microstructures were generated after DSR at 573 and 623 *** to mechanical properties,the yield strength(YS) and ultimate tensile strength(UTS) decreased monotonously with increasing rolling *** contrast,the elongation of the DSR-deformed samples was improved as the rolling temperature *** strain hardening exponent(n) calculated by Hollomon equation increased with increasing the rolling temperature,which would explain an increase in the uniform elongation.

关键词： Differential-speed rolling Magnesium alloy Mechani

Plastic anisotropy calculation of severely-deformed Al-Mg-Si alloy considering texture changes in electron backscatter diffraction

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Journal of Materials Science & Technology 2019年第7期35卷 1439-1443页

作者： I Putu Widiantara Hae Woong Yang Min Jun Kim young gun ko Plasticity Control & Mechanical Modeling Lab. School of Materials Science & Engineering Yeungnam University

The investigation studied the plastic anisotropy of the severely-deformed Al-Mg-Si alloy by considering texture *** sample deformed via asymmetrical rolling under cross-shear condition was annealed at 598 K where recrystallization was in *** is found upon annealing that the intensity of Cube({001})was comparable to those of plane-strain components while the intensities of shear components remained constant despite their instabilities in the recrystallization *** annealing,the average Lankford value(r)of the present sample was close to a unity whereas the in-plane anisotropy(△r)decreased,resulting in nearly isotropic characteristics of Al-Mg-Si alloy.

关键词： Al-Mg-Si alloy Anisotropy Recrystallization Microstructures

Improving the electrochemical stability of AZ31 Mg alloy in a 3.5wt.%NaCl solution via the surface functionalization of plasma electrolytic oxidation coating

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Journal of Magnesium and Alloys 2022年第5期10卷 1311-1325页

作者： Mosab Kaseem Tehseen Zehra Burak Dikici Ali Dafali Hae Woong Yang young gun ko Department of Nanotechnology and Advanced Materials Engineering Sejong UniversitySeoul 05006Republic of Korea Department of Metallurgical and Materials Engineering Ataturk UniversityErzurum 25240Turkey Faculty of Sciences Oujda Department of ChemistryMohamed the First UniversityOujdaMorocco Pohang Institute of Metal Industry Advancement Pohang 37666Republic of Korea Materials Electrochemistry Group School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea

The unique interactions between hexadecanoic acid(HA)and albumin(ALB)molecules on the surface of the porous layer of AZ31 Mg alloy were exploited to fabricate a novel hybrid composite film with excellent electrochemical stability in a 3.5 wt.%Na Cl ***,the inorganic layer(IL)obtained by plasma electrolytic oxidation of AZ31 Mg alloy in an alkaline-phosphate-WO_(3)electrolyte was soaked in an organic solution composed of ALB and HA for 10 and 24 h at 60℃.Although albumin and HA may coexist on the same surface of IL,the higher reactivity of ALB molecules would prevent the formation of a thick layer of *** donor-acceptor complexes formed due to the unique interactions between ALB and/or HA and IL surface would reduce the area exposed to the corrosive species which in turn would efficiently protect the substrate from *** porous structure of the IL would provide preferable sites for the physical and chemical locking triggered by charge-transfer phenomena,leading to the inhomogeneous nucleation and crystal growth of a flowery flakes-like organic *** calculations were performed to reveal the primary bonding modes between the ALB,HA,and IL and to assess the mechanistic insights into the formation of such novel hybrid composites.

关键词： Hybrid composite Coordination bond Albumin Fatty acid Porous layer Corrosion Theoretical approach

Experimental and theoretical investigation of high-entropy-alloy/support as a catalyst for reduction reactions

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Journal of Energy Chemistry 2023年第6期81卷 132-142,I0005页

作者： Wail Al Zoubi Bassem Assfour Abdul Wahab Allaf Stefano Leoni Jee-Hyun Kang young gun ko Materials Electrochemistry Laboratory School of Materials Science and EngineeringYeungnam UniversityGyeongsan 38541Republic of Korea Atomic Energy Commission Department of ChemistryP.O.Box 6091DamascusSyria Arab International University Department of Pharmaceutical Chemistry and Quality ControlFaculty of PharmacyGhabaghibDarraSyria Cardiff University School of ChemistryPark PlaceCF103AT CardiffUnited Kingdom School of Materials Science and Engineering Institute of Materials TechnologyYeungnam UniversityGyeongsan 38541Republic of Korea

Control of chemical composition and incorporation of multiple metallic elements into a single metal nanoparticle(NP)in an alloyed or a phase-segregated state hold potential scientific merit;however,developing libraries of such structures using effective strategies is challenging owing to the thermodynamic immiscibility of repelling constituent metallic ***,we present a one-pot interfacial plasma-discharge-driven(IP-D)synthesis strategy for fabricating stable high-entropy-alloy(HEA)NPs exhibiting ultrasmall size on a porous support ***,an electric field was applied for 120 s to enhance the incorporation of multiple metallic elements(i.e.,CuAgFe,CuAgNi,and CuAgNiFe)into ally ***,NPs were attached to a porous magnesium oxide surface via rapid *** solar light as the sole energy input,the CuAgNiFe catalyst was investigated as a reusable and sustainable material exhibiting excellent catalytic performance(100%conversion and 99% selectivity within1 min for a hydrogenation reaction)and consistent activity even after 20 cycles for a reduction reaction,considerably outperforming the majority of the conventional ***,the proposed strategy establishes a novel method for designing and synthesizing highly efficient and stable catalysts for the convertion of nitroarenes to anilines via chemical reduction.

关键词： Plasma Miscible Multicomponent Metal nanoparticle Nanocatalysts

A Self‑Regenerable Fiber Sloughing Its Heavy Metal Skin for Ultrahigh Separation Capability

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Advanced Fiber Materials 2023年第6期5卷 2127-2142页

作者： youngkyun Jung Ji Su Park Kyung‑Won Jung young gun ko Jae‑Woo Choi Center for Water Cycle Research Korea Institute of Science and TechnologySeoul 02792Republic of Korea Center for Bionics Korea Institute of Science and TechnologySeoul 02792Republic of Korea Department of Chemical Engineering and Materials Science Sangmyung UniversitySeoul 03016Republic of Korea Division of Energy&Environment Technology KIST SchoolKorea University of Science and Technology(UST)Seoul 02792Republic of Korea

Developing efficient separation materials for recovering metal resources from aqueous environments is crucial for the sustainable water–food–energy nexus,which addresses the interdependence between energy production,water production,and energy *** material-based separation processes have demonstrated outstanding ***,electric energy and chemicals are used to frequently replace the separation materials used in such processes owing to their short life *** study presents a methodology for designing the self-regenerable fiber(SRF)according to the types of metals through a self-regeneration *** SRF can semi-permanently recover the metal resources from water through a repetitive adsorption–crystallization–detachment process of metal ions on its *** ionic metal resources are adsorbed and crystallized with the counter-anions on the SRF ***,the metal crystals are self-detached from the SRF surface by the collision between the crystals and curvature and non-sticky surface of the ***,a module containing the SRF maintains its metal recovery capability even during continuous injection of the metal solution without its *** findings highlight the significance of interfacial engineering and further guide the rational design of energy/environmentally friendly resource recovery modules.

关键词： Self-regeneration model Self-regenerable fiber Semi-permanent adsorption capability Metal crystal growth-detachment