• Applied Chemistry for Engineering
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• v.22 no.1
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• pp.61-66
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• 2011

In this study, we prepared $TiO_2$ with the sol-gel method and controlled physico-chemical properties by a simple heat treatment. All materials were applied to photocatalytic decomposition of methylene blue and the material treated at 473 K showed the highest photocatalytic efficiency. The high performance resulted from a high adsorption amount of methylene blue due to a high surface area of $229.8m^2/g$. However, the material treated at 873 K, despite of a low surface area of $23.8m^2/g$ and a large particle size of 28.38 nm, exhibits a good photocatalytic performance due to the effect of mixed cyrstalline rutile and anatase phases formed by the high heat treatment temperature.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.749-752
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• 2001

Very fine cobalt oxide xerogel and ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. The results materials determine by using electrode that mixed ketjen black and PVdF. But CoO$\_$x/ have the low voltage, so we experimente to change electrolyte and various concentration.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.833-837
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• 2015

Li-air batteries have a promising future for because of their high energy density, which could theoretically be equal to that of gasoline. However, substantial Li-air cell performance limitations exist, which are related to the air cathode. The cell discharge products are deposited on the surfaces of the porous carbon materials in the air electrode, which blocks oxygen from diffusing to the reaction sites. Hence, the real capacity of a Li-air battery is determined by the carbon air electrode, especially by the pore volume available for the deposition of the discharged products. In this study, a simple and fast method is reported for the large-scale synthesis of carbon nanoballs (CNBs) consisting of a highly mesoporous structure for Li-air battery cathodes. The CNBs were synthesized by the solution plasma process from benzene solution, without the need for a graphite electrode for carbon growth. The CNBs so formed were then annealed to improve their electrical conductivity. Structural characterization revealed that the CNBs exhibited both an pore structure and high conductivity.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.577-580
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• 2001

Very fine cobalt oxide ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controlling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. But $CoO_x$ have the low voltage, so we experiment using Co/PVA composite electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11a
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• pp.577-580
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• 2001

Very fine cobalt oxide ambigel powder were prepared using a unique solution chemistry associated with the sol-gel process. The mesoporous structure of the initial gel is maintained by removing fluid under conditions where the capillary forces that result extraction are either low or no existent, are either low or nonexistent. Controling both the pore and solid architecture on the nanoscale offers a strategy for the design of supercapacitor. But $CoO_{x}$ have the low voltage, so we experiment using CO/PVA composite electrode.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.1231-1234
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• 2003

A sample procedure has been described to room temperature synthesis, mesoporous aluminosilicate materials with strong surface acidity by using a cationic surfactnat cetyltrimethylammonium bromide(CTABr) as the template agent. All samples were charecterized by X-ray diffraction(XRD) and nitrogen adsorption. The crystallinity and surface area of MCM-41 type aluminosilicats decrease with decreasing of Si/Al ratio. The influence of the aluminum contents of MCM-41 on the coordination of Al and on the acidity is studied by $^{27}Al$ MAS NMR and temperature programmed desorption of ammonia(TPD). It was shown that the incorporation of Al atoms into the framework causes increasing of acid site surface. And then Al atoms in the framework were incorporated tetrahedrally in structure, which gave a rise to cationic sites in the framework.

• Journal of Adhesion and Interface
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• v.24 no.4
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• pp.136-142
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• 2023

In this study, TEOS was used as a silica source, and a triblock copolymer (P123) was used as a template to produce mesoporous silica with a well-ordered hexagonal mesopore array through a self-assembly method and hydrothermal process under acidic condition. (Surfactant-extracted SBA-15). Surfactant-extracted SBA-15 showed the particle shape of a short rod with a size of approximately 980 nm. The surface area and pore diameter were 730 m²g^-1 and 70.8 Å, respectively. Meanwhile, aminosilane (3-aminopropyltriethoxysilane, APTES) was grafted into the mesopores using a post-synthesis method. Mesoporous silica (APTES-SBA-15) modified with aminosilane had a well-ordered pore structure (p6mm) and well-maintained the particle shape of short rods. The surface area and pore diameter of APTES-SBA-15 decreased to 350 m²g^-1 and 60.7 Å, respectively. APTES-modified mesoporous silica was treated with a solution of rare earth metal ions (Eu³⁺, Tb³⁺) to synthesize a mesoporous silica material in which rare earth metal complexes were introduced into the mesopores. (Eu/APTES-SBA-15, Tb/APTES-SBA-15) These materials exhibited characteristic photoluminescence spectra by λ_ex=250 nm. (⁵D₄→⁷F₅ (543.5 nm), ⁵D₄→⁷F₄ (583.5 nm), ⁵D₄→⁷F₃ (620.2 nm) transitions for Tb/APTES-SBA-15; ⁵D₀→⁷F₀ (577.7 nm), ⁵D₀→⁷F₁ (592.0 nm), ⁵D₀→⁷F₂ (614.9 nm), ⁵D₀→⁷F₃ (650.3 nm) and ⁵D₀→⁷F₄ (698.5 nm) transitions for Eu/APTES-SBA-15)

• Bulletin of the Korean Chemical Society
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• v.25 no.5
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• pp.634-638
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• 2004

Titanium silicalite-1 (TS-1) molecular sieve was produced by microwave heating of amorphous titanium-containing solid precursors after impregnation with aqueous TPAOH solution. $SiO_2-TiO_2$ xerogel, sub-micron sized $SiO_2-TiO_2$ prepared by thermal plasma process, and Ti-containing mesoporous silica, Ti-HMS, were tested as the solid phase substrates. Highly crystalline product was obtained within 30 min. after microwave irradiation with yields over 90% using $SiO_2-TiO_2$ xerogel, which showed essentially identical physicochemical properties to TS-1 prepared by conventional hydrothermal method. Excellent catalytic activity was also obtained for 1-hexene epoxidation using $H_2O_2.\;SiO_2-TiO_2$ particles prepared by thermal plasma and Ti-HMS were found inferior as a substrate for TS-1, probably due to difficulties in wetting the surface uniformly with TPAOH.

• Journal of Advanced Marine Engineering and Technology
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• v.39 no.8
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• pp.838-842
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• 2015

The Li-air battery is a promising candidate for the most energy-dense electrochemical power source because it has 5 to 10 times greater energy storage capacity than that of Li-ion batteries. However, the Li-air cell performance falls short of the theoretical estimate, primarily because the discharge terminates well before the pore volume of the air electrode is completely filled with lithium oxides. Therefore, the structure of carbon used in the air electrode is a critical factor that affects the performance of Li-air batteries. In a previous study, we reported a new class of carbon nanomaterial, named carbon nanoballs (CNBs), consisting of highly mesoporous spheres. Structural characterization revealed that the synthesized CNBs have excellent a meso-macro hierarchical pore structure, with an average diameter greater than 10 nm and a total pore volume more than $1.00cm^3g^{-1}$. In this study, CNBs are applied in an actual Li-air battery to evaluate the electrochemical performance. The formation mechanism and electrochemical performance of the CNBs are discussed in detail.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.215-221
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• 2005

A Fe-containing mesoporous silica (Fe-MCM-41) in which part of Si in the framework was replaced by Fe(Si-O-Fe) has been successfully prepared using $Fe^{3+}$ salt by a direct synthesis route. Physical properties of the material were characterized by XRD, $N_2$ adsorption, SEM/TEM, UV-vis and FT-IR spectroscopies. Fe-MCM-41 exhibited high catalytic activity in phenol hydroxylation using $H_2O_2$ as oxidant, giving phenol conversion of ca. 60% at $50^{\circ}C$ [phenol : $H_2O_2$ = 1:1, water solvent]. Fe-MCM-41 was also applied to the growth of CNTs, utilizing a thermal-CVD reactor using acetylene gas, which demonstrated that multi-wall CNTs could be prepared efficiently using the Fe-MCM-41 catalyst.