Highly safe lithium-ion batteries (LIBs) are required for large-scale applications such as electrical vehicles and energy storage systems. A highly stable cathode is essential for the development of safe LIBs. LiFePO4 is one of the most stable cathodes because of its stable structure and strong bonding between P and O. However, it has a lower energy density than lithium transition metal oxides. To investigate the high energy density of phosphate materials, vanadium phosphates were investigated. Vanadium enables multiple redox reactions as well as high redox potentials. LiVPO4O has two redox reactions (V5+/V4+/V3+) but low electrochemical activity. In this study, LiVPO4O is doped with fluorine to improve its electrochemical activity and increase its operational redox potential. With increasing fluorine content in LiVPO4O1-xFx, the local vanadium structure changed as the vanadium oxidation state changed. In addition, the operating potential increased with increasing fluorine content. Thus, it was confirmed that fluorine doping leads to a strong inductive effect and high operating voltage, which helps improve the energy density of the cathode materials.

A mono-type glycerine fatty acid ester compound was chemically synthesized using medium-chain fatty acids with antibacterial activity, and the physicochemical quality and antibacterial activity of the synthesized glycerine medium-chain fatty acid ester compound were measured. At a reaction molar ratio of MCT(medium chain triglyceride) to glycerine of 1:2.5, 48.15% mono ester was produced. The physicochemical analysis of the synthesized glycerine fatty acid ester compound showed an acid content of 0.38~0.60%, which tended to increase slightly as the glycerine molar ratio increased. The saponification value decreased as the synthesized molar ratio of glycerine increased from 218 to 284. The number of bacteria was measured to confirm the degree of antibacterial activity of glycerine medium-chain fatty acid esters against food poisoning bacteria, Bacillus cereus and Salmonella typhi. The number of bacteria significantly decreased as the MCT:glycerine molar ratio increased. In particular, the antibacterial effect between the treatment groups was the highest when at an MCT:glycerine molar ratio of 1:2.5.

Tin-antimony sulfide nanocomposites were prepared via hydrothermal synthesis and a N2 reduction process for use as a negative electrode in a sodium ion battery. The electrochemical energy storage performance of the battery was analyzed according to the tin-antimony composition. The optimized sulfides exhibited superior charge/discharge capacity (770 mAh g-1 at a current density of 100 mA g-1) and stable lifespan characteristics (71.2 % after 200 cycles at a current density of 500 mA g-1). It exhibited a reversible characteristic, continuously participating in the charge-discharge process. The improved electrochemical energy storage performance and cycle stability was attributed to the small particle size, by controlling the composition of the tin-antimony sulfide. By optimizing the tin-antimony ratio during the synthesis process, it did not deviate from the solubility limit. Graphene oxide also acts to suppress volume expansion during reversible electrochemical reaction. Based on these results, tin-antimony sulfide is considered a promising anode material for a sodium ion battery used as a medium-to-large energy storage source.

In this study, (GaN)1-x(ZnO)x solid solution nanoparticles with a high zinc content are prepared by ultrasonic spray pyrolysis and subsequent nitridation. The structure and morphology of the samples are investigated by X-ray diffraction (XRD), field-emission scanning electron microscopy, and energy-dispersive X-ray spectroscopy. The characterization results show a phase transition from the Zn and Ga-based oxides (ZnO or ZnGa2O4) to a (GaN)1-x (ZnO)x solid solution under an NH3 atmosphere. The effect of the precursor solution concentration and nitridation temperature on the final products are systematically investigated to obtain (GaN)1-x(ZnO)x nanoparticles with a high Zn concentration. It is confirmed that the powder synthesized from the solution in which the ratio of Zn and Ga was set to 0.8:0.2, as the initial precursor composition was composed of about 0.8-mole fraction of Zn, similar to the initially set one, through nitriding treatment at 700oC. Besides, the synthesized nanoparticles exhibited the typical XRD pattern of (GaN)1-x(ZnO)x, and a strong absorption of visible light with a bandgap energy of approximately 2.78 eV, confirming their potential use as a hydrogen production photocatalyst.

3 mol% yttria-doped stabilized zirconia (3YSZ) is synthesized by a solvothermal process, and its characteristics are investigated using various methods. Also, the dispersibility of synthesized 3YSZ nanoparticles is observed with the species of surface modifier. The 3YSZ nano sol prepared with an optimum condition is employed in prism coating and its properties are evaluated. The synthesized 3YSZ nanoparticles show a globular shape with about 10 to 20 nm crystallite size. The mixed phases with the nano sol show a high specific surface of 178 m2/g. The prism sheet coated with the 3YSZ nano sol present an excellent refractive index, transmittance, and luminance; refractive index is 1.603, transmittance is 90.2 %, and luminance of coating film is improved by 5.9 % compared to that of the film without 3YSZ nano sol. It is verified that the surface modified 3YSZ is suitable as the prism sheet for optical displays.

Synthesizing one-dimensional nanostructures of oxide semiconductors is a promising approach to fabricate highefficiency photoelectrodes for hydrogen production from photoelectrochemical (PEC) water splitting. In this work, vertically aligned zinc oxide (ZnO) nanorod arrays are successfully synthesized on fluorine-doped-tin-oxide (FTO) coated glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Zn metal thin film. The structural, optical and PEC properties of the ZnO nanorod arrays synthesized at varying levels of Zn sputtering power are examined to reveal that the optimum ZnO nanorod array can be obtained at a sputtering power of 20W. The photocurrent density and the optimal photocurrent conversion efficiency obtained for the optimum ZnO nanorod array photoanode are 0.13 mA/cm2 and 0.49 %, respectively, at a potential of 0.85 V vs. RHE. These results provide a promising avenue to fabricating earth-abundant ZnO-based photoanodes for PEC water oxidation using facile hydrothermal synthesis.

본 연구는 1M Li2SO4 및 1M Na2SO4 수용액에서 CoSe 나노 입자의 전기 화학적 성능을 조사 하였다. CoSe 나노 입자의 전기 화학적 효율은 1M Na2SO4 전해질에서 더 높은 비정전 용량을 보여주는 결 과를 얻었고 이것은 주로 1M Na2SO4 용액의 벌크 전해질에서 수화 된 이온의 빠른 이동과 활물질에 의해 제공되는 낮은 전기 화학적 임피던스가 원인이라 사료된다. 또한, 순환 전압 전류법 안정성 실험에서 25 mV s-1의 스캔 속도로 1000 회 연속 순환 전압 전류 측정주기 후에도 각각 1M Na2SO4 및 1M Li2SO4에서 약 92 % 및 89 %의 특정 정전 용량의 유지를 보여주었다. 이 연구는 새로운 하이브리드 슈퍼 커패시터를 개발하기 위한 기초 데이터를 제공하며 비대칭 슈퍼 커패시터의 양극으로 사용될 수 있음을 시사한다.

Transition metal oxide is widely used as a water electrolysis catalyst to substitute for a noble metal catalyst such as IrO2 and RuO2. In this study, the sol-gel method is used to synthesize the CuxCo3-xO4 catalyst for the oxygen evolution reaction (OER),. The CuxCo3-xO4 is synthesized at various calcination temperatures from 250 ℃ to 400 ℃ for 4 h. The CuxCo3- xO4 synthesized at 300 ℃ has a perfect spinel structure without residues of the precursor and secondary phases, such as CuO. The particle size of CuxCo3-xO4 increases with an increase in calcination temperature. Amongst all the samples studied, CuxCo3- xO4, which is synthesized at 300?, has the highest activity for the OER. Its onset potential for the OER is 370 mV and the overpotential at 10 mA/cm2 is 438 mV. The tafel slope of CuxCo3-xO4 synthesized at 300 ℃ has a low value of 58 mV/dec. These results are mainly explained by the increase in the available active surface area of the CuxCo3-xO4 catalyst.

Using a high pressure homonizer, we report on the electrochemical performance of Li4Ti5O12(LTO) particles manufactured as anode active material for lithium ion battery. High-pressure synthesis processing is performed under conditions in which the mole fraction of Li/Ti is 0.9, the synthesis pressure is 2,000 bar and the numbers of passings-through are 5, 7 and 10. The observed X-ray diffraction patterns show that pure LTO is manufactured when the number of passings-through is 10. It is found from scanning electron microscopy analysis that the average size of synthesized particles decreases as the number of passings-through increases. LiCoO2-based active cathode materials are used to fabricate several coin half/full cells and their battery characteristics such as lifetime, rate capability and charge transfer resistance are then estimated, revealing quite good electrochemical performance of the LTO particles as an effective anode active material for lithium secondary batteries.

Hydrothermal synthesis of highly crystalline TiO2 nanorods is a well-developed technique and the nanorods have been widely used as the template for growth of various core-shell nanorod structures. Magneli/CdS core-shell nanorod structures are fabricated for the photoelectrochemical cell (PEC) electrode to achieve enhanced carrier transport along the metallic magneli phase nanorod template. However, the long and thin TiO2 nanorods may form a high resistance path to the electrons transferred from the CdS layer. TiO2 nanorods synthesized are reduced to magneli phases, TixO2x-1, by heat treatment in a hydrogen environment. Two types of magneli phase nanorods of Ti4O7 and Ti3O5 are synthesized. Structural morphology and X-ray diffraction analyses are carried out. CdS nano-films are deposited on the magneli nanorods for the main light absorption layer to form a photoanode, and the PEC performance is measured under simulated sunlight irradiation and compared with the conventional TiO2/CdS core-shell nanorod electrode. A higher photocurrent is observed from the stand-alone Ti3O5/CdS coreshell nanorod structure in which the nanorods are grown on both sides of the seed layer.

Various carbon aerogels (CAs) were prepared from polymerization of resorcinol and formaldehyde and applied as the electrode materials of an electric double layer capacitor (EDLC) with the aim of controlling the textural and electrochemical properties of CAs by the type of base catalyst and the ratio of resorcinol to catalyst (R/C). The CAs from NaHCO3 and KHCO3 with H+ ions had higher specific surface areas but exhibited lower electrochemical properties than those from K2CO3 and Na2CO3, which had more uniform pore size distributions. The electrochemical properties of Na2CO3 were superior to those of K2CO3 probably because the polarizing power of Na+ ions was higher than K+ ions. With an increasing R/C ratio, the pore sizes of CA showed a tendency to increase but the uniformity of the pore size distribution got worse. For the four base catalysts, the highest electrochemical property was obtained at the R/C ratio of 500.

Copper nanoparticles attract much attention as substitutes of noble metals such as silver and can help reduce the manufacturing cost of electronic products due to their lower cost and good conductivity. In the present work, the chemical reduction is examined to optimize the synthesis of nano-sized copper particles from copper sulfate. Sodium borohydride and ascorbic acid are used as reducing and antioxidant agents, respectively. Polyethylene glycol (PEG) is used as a size-control and capping agent. An appropriate dose of PEG inhibits the abnormal growth of copper nanoparticles, maintaining chemical stability. The addition of ascorbic acid prevents the oxidation of nanoparticles during synthesis and storage. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate the size of the synthesized nanoparticles and the coordination between copper nanoparticles and PEG. For chemical reduction, copper nanoparticles less than 100 nm in size without oxidized layers are successfully obtained by the present method.

In this study, titanium(Ti) meshes and porous bodies are employed to synthesize carbon nanotubes(CNTs) using methane(CH4) gas and camphene solution, respectively, by chemical vapor deposition. Camphene is impregnated into Ti porous bodies prior to heating in a furnace. Various microscopic and spectroscopic techniques are utilized to analyze CNTs. It is found that CNTs are more densely and homogeneously populated on the camphene impregnated Ti-porous bodies as compared to CNTs synthesized with methane on Ti-porous bodies. It is elucidated that, when synthesized with methane, few CNTs are formed inside of Ti porous bodies due to methane supply limited by internal structures of Ti porous bodies. Ti-meshes and porous bodies are found to be multi-walled with high degree of structural disorders. These CNTs are expected to be utilized as catalyst supports in catalytic filters and purification systems.

Carbazole과 diketopyrrolopyrrole를 기본 골격으로 한 2,5-bis-(2-butyl-octyl)-3,6-bis-[5-(4-carbazol-9-ylphenyl)-thiophen-2-yl] -2,5-dihydro-pyrrolo[3,4-c]pyrrole-1,4-dione (PCTDPP12)을 스즈키 커플링 반응을 이용하여 합성하였다. UV-Visible 분광법으로 확인 한 결과 PCTDPP의 용액과 필름의 최대 흡수 피크는 각각 643 nm와 671 nm이며, PCTDPP12의 광학적 밴드갭은 각각 1.84 eV이다. 열처리에 의해 PCTDPP12의 UV-visible 흡광도 및 최대 흡수 파장이 변화된는 것을 관찰 하였다. 그리고 순환 전압 전류법에 의해 조사한 PCTDPP12의 HOMO 및 LUMO 에너지 준위는 –5.34 eV와 -3.54 eV 이다.

Pt has been widely used as catalyst for fuel cell and exhausted gas clean systems due to its high catalytic activity.Recently, there have been researches on fabricating composite materials of Pt as a method of reducing the amount of Pt due toits high price. One of the approaches for saving Pt used as catalyst is a core shell structure consisting of Pt layer on the core ofthe non-noble metal. In this study, the synthesis of Pt shell was conducted on the surface of TiO2 particle, a non-noble material,by applying ultraviolet (UV) irradiation. Anatase TiO2 particles with the average size of 20~30 nm were immersed in the eth-anol dissolved with Pt precursor of H2PtCl6·6H2O and exposed to UV irradiation with the wavelength of 365 nm. It was con-firmed that Pt nano-particles were formed on the surface of TiO2 particles by photochemical reduction of Pt ion from the solution.The morphology of the synthesized Pt@TiO2 nano-composite was examined by TEM (Transmission Electron Microscopy).