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Li, Yali,Li, Qianwen,Sun, Chengbin,Jin, Sila,Park, Yeonju,Zhou, Tieli,Wang, Xu,Zhao, Bing,Ruan, Weidong,Jung, Young Mee Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.427 No.2
<P><B>Abstract</B></P> <P>A new type of surface-enhanced Raman scattering (SERS) substrate was fabricated through the layer-by-layer self-assembly of silver nanoparticles (AgNPs, av. 45nm in diameter) and porous gold nanoclusters/nanoparticles (AuNPs, av. 143nm in diameter). The development of the porosity of the AuNPs was investigated, and successful SERS applications of the porous AuNPs were also examined. As compared with AgNP films, the enhancement factor of Ag-Au compound substrates is increased 6 times at the concentration of 10<SUP>−6</SUP> M. This additional enhancement contributes to the trace-amount-detection of target molecules enormously. The contribution is generated through the increase of the usable surface area arising from the nanoscale pores distributed three-dimensionally in the porous AuNPs, which enrich the adsorption sites and hot spots for the adsorption of probe molecules, making the developed nanofilms highly sensitive SERS substrates. The substrates were used for the detection of a physiological metabolite of urea molecules. The results reached to a very low concentration of 1mM and exhibited good quantitative character over the physiological concentration range (1∼20mM) under mimicking biophysical conditions. These results show that the prepared substrate has great potential in the ultrasensitive SERS-based detection and in SERS-based biosensors.</P> <P><B>Highlights</B></P> <P> <UL> <LI> A new type of SERS substrate, consisting of silver nanoparticles and porous gold nanoparticles was fabricated. </LI> <LI> An additional enhancement contribution generated from the porous characteristic of gold nanoparticles. </LI> <LI> The substrates were used for the detection of a physiological metabolite of urea molecules. </LI> <LI> The results exhibited good quantitative character over all the physiological concentration range (1∼20 mM). </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Li, Chengbin,Li, Zhenghua,Oh, Hwa Yong,Hong, Gyong Hee,Park, Jin Seo,Kim, Ji Man Elsevier 2018 CATALYSIS TODAY - Vol.307 No.-
<P><B>Abstract</B></P> <P>Highly ordered mesoporous Cu-Mn-Ce ternary metal oxide materials with various Cu/Mn molar ratios were successfully synthesized by using a nano-casting method from a mesoporous silica template with a cubic <I>Ia</I>3<I>d</I> mesostructure. The ternary metal oxide materials were characterized by X-ray diffraction (XRD), N<SUB>2</SUB>-sorption, electron microscopy, Raman spectroscopy, H<SUB>2</SUB>-temperature programmed reduction and CO-temperature programmed desorption. The XRD results indicated that the materials did not show any diffraction peaks corresponding to copper and manganese oxides, ensuring the formation of Cu<I> <SUB>x</SUB> </I>Mn<SUB>0.2-<I>x</I> </SUB>Ce<SUB>0.8</SUB>O<SUB>2</SUB> (<I>x</I> =0–0.2). The WGS activity of the ternary metal oxide catalysts increased as the molar ratios of Cu/Mn increased. Among the catalysts, the mesoporous Cu<SUB>0.18</SUB>Mn<SUB>0.02</SUB>Ce<SUB>0.8</SUB>O<SUB>2</SUB> catalyst exhibited the best catalytic activity in low temperature range with zero methane yield. Moreover, this catalyst showed excellent catalytic stability during the reaction. The observed enhancement in the WGS performances were attributed to high surface area, uniform crystalline framework with increased structural defect, highly dispersed copper and manganese within the ceria lattice or on the surface, and strong metal support interaction.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ordered mesoporous Cu-Mn-Ce ternary metal oxide catalyst showed an excellent WGS reaction performances. </LI> <LI> Copper and manganese, incorporated within the CeO<SUB>2</SUB> lattice, enhanced the activity. </LI> <LI> Mesoporous ternary metal oxides exhibited good nanostructural and catalytic stabilities. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
You, Dae Jong,Kim, Do Hyung,De Lile, Jeffrey Roshan,Li, Chengbin,Lee, Seung Geol,Kim, Ji Man,Pak, Chanho Elsevier 2018 Applied catalysis. A, General Vol.562 No.-
<P><B>Abstract</B></P> <P>Pd-based core-shell alloy-supported catalysts were prepared sequentially via a microwave-assisted polyol method and galvanic replacement. To investigate the effect of the core composition on the catalytic activity of such catalysts, three different Pd alloy cores (PdNi, PdCu, and PdNiCu) were prepared on carbon supports using a polyol method. Then, Pd and Ir were introduced simultaneously to form shells on the Pd alloy cores by galvanic replacement in aqueous solution, thereby producing catalysts designated as PdNi@PdIr/C, PdCu@PdIr/C, and PdNiCu@PdIr/C. X-ray diffraction revealed that all three catalysts exhibited the face-centered cubic structure of Pd without the presence of individual phases for Ni, Cu, and Ir. The core-shell structure of the Pd-based alloy nanoparticles on the carbon support was verified by the electron energy loss spectroscopy line profile of a 25 nm nanoparticle of PdNiCu@PdIr/C. Among the three Pd-based core-shell catalysts, the highest electrochemical surface area and oxygen reduction reaction (ORR) activity was observed for PdNiCu@PdIr/C. In addition, the membrane electrode assembly employing the PdNiCu@PdIr/C catalyst displayed a significantly improved voltage compared to the other two catalysts under high-temperature polymer electrolyte membrane fuel cell conditions at 150 °C. Single-cell durability tests conducted to measure the voltage change at a constant current density of 0.2 A cm<SUP>−2</SUP> showed a decay ratio of 12.3 μV h<SUP>−1</SUP>. These results suggest that the composition of the core in core-shell nanoparticles has an important influence on both the electronic properties in the Pd alloy core and compressive lattice strain on the PdIr shell. Control of these synergistic effects provides a new approach for developing catalysts with high ORR activity.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Three catalysts with PdNi, PdNiCu and PdCu cores and a PdIr shell were prepared by polyol method and galvanic replacement. </LI> <LI> A membrane electrode assembly with PdNiCu@PdIr/C catalyst showed the significantly improved performance and durability. </LI> <LI> The core component of core-shell catalysts has important role to improve the activity toward the oxygen reduction reaction. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Li, Chengbin,Oh, Hwa-Yong,Cho, Hye-Jin,Kumarsrininasan, Sivaranjani,Choi, Jong-Ha,Li, Zhenghua,Hong, Gyoung-Hee,Park, Su-Bin,Kim, Ji Man American Scientific Publishers 2016 Journal of nanoscience and nanotechnology Vol.16 No.11
<P>Binary oxide catalyst (Cu0.15Co2.84O4) supported on mesoporous CeO2 has been prepared by an incipient wetness impregnation method. The produced catalysts with different loading of binary oxide (0-30 wt%) have been thoroughly characterized and applied for a water-gas shift (WGS) reaction. The characterization results indicate that the binary oxide catalysts are highly dispersed on the mesoporous CeO2 support without significant loss of mesostructural properties, even though the catalyst loading reaches 30 wt%. The highest catalytic activity towards WGS reaction has been achieved from the 30 wt% Cu0.15Co2.84O4/CeO2 catalyst, showing 100% CO conversion and very low methane yield (nearly zero%) at relatively low temperature (similar to 300 degrees C). The present Cu0.15Co2.84O4/CeO2 catalyst can be recycled more than three times with loss of the activity. Metallic cobalt species are formed during the reaction, whose structural properties are maintained under the repeated WGS reaction conditions. Excellent catalytic activity and durability originate from the highly dispersed binary oxides on the pore surface of mesoporous CeO2, which is probably due to the strong metal-support interaction.</P>
Ordered Mesoporous Cu—Co—CeO<sub>2</sub> Catalyst for Water-Gas Shift Reaction at High Temperature
Li, Chengbin,Li, Zhenghua,Park, Su Bin,Hong, GyoungHee,Park, Jin Seo,Oh, Hwa Yong,Kim, Ji Man American Scientific Publishers 2017 Journal of nanoscience and nanotechnology Vol.17 No.11
<P>Highly ordered mesoporous Cu-Co-CeO2 composite catalysts with different Cu/Co ratios were synthesized via a nano-replication method using a mesoporous silica template with cubic laid mesostructure, and the ternary oxide catalysts, thus obtained, were used for a water-gas shift reaction. Combined characterization results, using X-ray diffraction, electron microscopy, N-2 adsorption, and temperature-programmed reduction analysis techniques, reveal that the incorporation of copper and cobalt into the ceria lattice not only promotes the formation of structure defects, but also increases the redox properties. Furthermore, some CoOx, clusters, formed on the catalysts surface, which enhanced the catalytic activity at high temperature. Among the series of composite catalysts, the Cu0.1Co0.1Ce0.8O2 catalyst showed the highest catalytic performance with a zero methane yield.</P>
Gyoung Hee Hong,Zhengyang Li,박진서,Zhenghua Li,Ki Yeong Kim,Chengbin Li,이정호,Mingshi Jin,Galen D. Stucky,Ji Man Kim 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.107 No.-
Highly ordered mesoporous molybdenum dioxide (meso-MoO2) was successfully synthesized by a nanoreplicationmethod using a mesoporous silica template with 3D cubic Ia3d mesostructure. Structuralanalyses using X-ray diffraction, N2 sorption, and electron microscopy indicated that the meso-MoO2material exhibited high surface area (106 m2/g), large pore volume (0.66 cm3/g), and well-defined mesopores. Under the optimized reaction conditions, the meso-MoO2 catalyst showed excellent catalytic performancesfor the acetalization of glycerol with acetone (95.8% of glycerol conversion, and 97.8% ofsolketal selectivity) at 20 C, due to its high surface area with large number of acid sites. During recycling,the meso-MoO2 catalyst exhibited a slight decrease in activity; and after a simple regeneration at 350 C,the catalytic performances could be completely recovered. More importantly, a partial hydrophobic treatmentof the meso-MoO2 catalyst dramatically enhanced the water-tolerance during the catalytic reaction.
Chengbin Shi,Xin Zheng,Zhanbing Yang,Peng Lan,Jing Li,Fang Jiang 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.9
The microstructure and primary carbides in the steel billets produced by an industrial-scale electroslag rapid remelting(ESRR) at different melting rates were studied. The amount and size of primary carbides MC and M2Cat the center of theremelted ingots is larger than that at the mid-radius of the remelted ingots. The amount of primary carbides and secondarydendrite arm spacing of the ingot increase with the increase in the melting rates of ESRR, caused by the increase inthe local solidification time. The microsegregation of Mo in the remelted ingots after annealing is most serious among thecarbide-forming elements. The microsegregation of Mo and Cr increases linearly with increasing the melting rate, and themicrosegregation of V keeps nearly constant with further increasing the melting rate from 400 to 500 kg/h. Increasing themelting rate of ESRR do not change the types of primary carbides until 500 kg/h, at which another type of primary carbideM7C3is formed. The amount of the primary carbides and the microsegregation degree of Mo, V and Cr in the ESRR billetsat the melting rate of 400 kg/h is nearly same as that produced by same-scale conventional ESR.
이재하,( Chengbin Li ),강성수,김지만,박정원,김도희 한국공업화학회 2020 한국공업화학회 연구논문 초록집 Vol.2020 No.-
‘Pt on CeO<sub>2</sub>’ exhibits good high temperature water-gas-shift (HT-WGS) reaction activity. However, Pt also catalyze the formation of CH<sub>4</sub> as by-product, which places the limitation on the use of Pt/CeO<sub>2</sub> as HT-WGS catalyst. To suppress CH<sub>4</sub> formation while maintaining high WGS reaction activity, the type of catalysts with Pt nanoparticles (NP) encapsulated in CeO<sub>2</sub> over-layers (‘Pt in CeO<sub>2</sub>’) were prepared by applying controlled reductive treatments. CH<sub>4</sub> production was successfully inhibited on ‘Pt in CeO<sub>2</sub>’ while high WGS reaction activity was maintained. Thin CeO<sub>2</sub> over-layers interacting with Pt NP possessed high concentration of oxygen vacancies, and could catalyze WGS reaction.