Photoelectrochemical cells have been used in photolysis of water to generate hydrogen as a clean energy source. A high efficiency electrode for photoelectrochemical cell systems was realized using a ZnO hierarchical nanostructure. A ZnO nanofiber mat structure was fabricated by electrospinning of Zn solution on the substrate, followed by oxidation; on this substrate, hydrothermal synthesis of ZnO nanorods on the ZnO nanofibers was carried out to form a ZnO hierarchical structure. The thickness of the nanofiber mat and the thermal annealing temperature were determined as the parameters for optimization. The morphology of the structures was examined by field-emission scanning electron microscopy, transmission electron microscopy, and X-ray diffraction. The performance of the ZnO nanofiber mat and the potential of the ZnO hierarchical structures as photoelectrochemical cell electrodes were evaluated by measurement of the photoelectron conversion efficiencies under UV light. The highest photoconversion efficiency observed was 63 % with a ZnO hierarchical structure annealed at 400˚C in air. The morphology and the crystalline quality of the electrode materials greatly influenced the electrode performance. Therefore, the combination of the two fabrication methods, electrospinning and hydrothermal synthesis, was successfully applied to fabricate a high performance photoelectrochemical cell electrode.

Synthesis of sub-micron 2SnO·(H2O) powders by chemical reduction process was performed at room temperature as function of viscosity of methanol solution and molecular weight of PVP (polyvinylpyrrolidone). Tin(II) 2-ethylhexanoate and sodium borohydride were used as the tin precursor and the reducing agent, respectively. Simultaneous calcination and sintering processes were additionally performed by heating the 2SnO·(H2O) powders. In the synthesis of the 2SnO·(H2O) powders, it was possible to control the powder size using different combinations of the methanol solution viscosity and the PVP molecular weight. The molecular weight of PVP particularly influenced the size of the synthesized 2SnO·(H2O) powders. A holding time of 1 hr in air at 500˚C sufficiently transformed the 2SnO·(H2O) into SnO2 phase; however, most of the PVP (molecular weight: 1,300,000) surface-capped powders decomposed and was removed after heating for 1 h at 700˚C. Hence, heating for 1 h at 500˚C made a porous SnO2 film containing residual PVP, whereas dense SnO2 films with no significant amount of PVP formed after heating for 1 h at 700˚C.

N,N,N-Trimethyl-10-nitrophenoxy decylammonium bromide (N10TAB) and N,N,N,N-Tetramethyl-bis-〔10-nitrophenoxy decyl〕-1,6-hexanediammonium dibromide (N10-6-10N), bearing aromatic nitrophenoxy group in the end of their hydrophobic chains have been prepared, and their properties in aqueous solutions have been studied by conductivity and H-NMR spectroscopy. Below the critical micelle concentration N10-6-10N form premicelle with two or three surfactant molecules. Beyond the critical micelle concentration two molecules have strong self-aggregation ability and form micelles of rather small size and with small aggregation numbers. H-NMR at different concentrations give the informations on the environmental changes of the surfactants on their micellization progress.

Mass production-capable powder was synthesized for use as cathode material in state-of-the-art lithium-ion batteries. These batteries are main powder sources for high tech-end digital electronic equipments and electric vehicles in the near future and they must possess high specific capacity and durable charge-discharge characteristics. Amorphous silicone was quite superior to crystalline one as starting material to fabricate silicone oxide with high reactivity between precursors of sol-gel type reaction intermediates. The amorphous silicone starting material also has beneficial effect of efficiently controlling secondary phases, most notably . Lastly, carbon was coated on powders by using sucrose to afford some improved electrical conductivity. The carbon-coated cathode material was further characterized using SEM, XRD, and galvanostatic charge/discharge test method for morphological and electrochemical examinations. Coin cell was subject to 1.5-4.8 V at C/20, where 74 mAh/g was observed during primary discharge cycle.

We present a method of graphene synthesis with high thickness uniformity using the thermal chemical vapor deposition (TCVD) technique; we demonstrate its application to a grid supporting membrane using transmission electron microscope (TEM) observation, particularly for nanomaterials that have smaller dimensions than the pitch of commercial grid mesh. Graphene was synthesized on electron-beam-evaporated Ni catalytic thin films. Methane and hydrogen gases were used as carbon feedstock and dilution gas, respectively. The effects of synthesis temperature and flow rate of feedstock on graphene structures have been investigated. The most effective condition for large area growth synthesis and high thickness uniformity was found to be 1000˚C and 5 sccm of methane. Among the various applications of the synthesized graphenes, their use as a supporting membrane of a TEM grid has been demonstrated; such a grid is useful for high resolution TEM imaging of nanoscale materials because it preserves the same focal plane over the whole grid mesh. After the graphene synthesis, we were able successfully to transfer the graphenes from the Ni substrates to the TEM grid without a polymeric mediator, so that we were able to preserve the clean surface of the as-synthesized graphene. Then, a drop of carbon nanotube (CNT) suspension was deposited onto the graphene-covered TEM grid. Finally, we performed high resolution TEM observation and obtained clear image of the carbon nanotubes, which were deposited on the graphene supporting membrane.

We synthesized porous Co3O4/RuO2 composite using the soft template method. Cetyl trimethyl ammonium bromide (CTAB) was used to make micell as a cation surfactant. The precipitation of cobalt ion and ruthenium ion for making porosity in particles was induced by OH- ion. The porous Co3O4/RuO2 composite was completely synthesiszed after anealing until 250˚C at 3˚C/min. From the XRD ananysis, we were able to determine that the porous Co3O4/RuO2 composite was comprised of nanoparticles with low crystallinity. The shape or structure of the porous Co3O4/RuO2 composite was studied by FE-SEM and FE-TEM. The size of the porous Co3O4/RuO2 composite was 20~40 nm. From the FE-TEM, we were able to determine that porous cavities were formed in the composite particles. The electrochemical performance of the porous Co3O4/RuO2 composite was measured by CV and charge-discharge methods. The specific capacitances, determined through cyclic voltammetry (CV) measurement, were ~51, ~47, ~42, and ~33 F/g at 5, 10, 20, and 50 mV/sec scan rates, respectively. The specific capacitance through charge-discharge measurement was ~63 F/g in the range of 0.0~1.0 V cutoff voltage and 50 mAh/g current density.

WCl6-EtAlCl2 촉매계를 이용하여 비교적 큰 분자량을 갖는 폴리(페닐아세틸렌)을 합성하였다. 중합반응이 잘 진행되었으며 중합수율은 81%였다. 합성한 폴리(페닐아세틸렌) 분자구조를 NMR(1H-,13C-), IR, UV-visible, 원소분석 등으로 분석한 결과 페닐 치환기를 갖는 공액구조 고분자가 합성되었음을 확인할 수 있었다. 아울러 332 nm의 빛으로 여기시킬 경우 PL 최대 peak는 424 nm에서 관찰되었는데, 이는 2.93 eV의 광 에너지에 해당한다. 이 고분자의 순환 전압전류 그림은 도핑과 탈도핑사이에서 비가역적인 전기화학적 거동을 보여주었다. 이 고분자의 전기화학적 과정이 매우 안정하였으며, 스캔속도에 따른 산화전류 밀도 실험으로부터 이 고분자의 산화-환언 과정은 확산-제어과정에 따르는 것으로 분석되었다.

Nano-technology is a super microscopic technology to deal with structures of 100 nm or smaller. This technology also involves the developing of TiO2 materials or TiO2 devices within that size. The aim of the present paper is to synthesize WOx doped nano-TiO2 by the Sonochemistry method and to evaluate the effect of different percentages (0.5-5 wt%) of tungsten oxide load on TiO2 in methylene blue (MB) elimination. The samples were characterized using such different techniques as X-ray diffraction (XRD), TEM, SEM, and UV-VIS absorption spectra. The photo-catalytic activity of tungsten oxide doped TiO2 was evaluated through the elimination of methylene blue using UV-irradiation (315-400nm). The best result was found with 5 wt% WOx doped TiO2. It has been confirmed that WOx-TiO2 could be excited by visible light (E<3.2 eV) and that the recombination rate of electrons/holes in WOx-TiO2 declined due to the existence of WOx doped in TiO2.

마이크로파를 열원으로 이용하는 화학반응은 어려운 반응을 활성화시킬 수 있고 반응시간과 속도를 가속화하여 고수득율 및 높은 분자량을 얻는 고분자를 합성하는데 유용하게 쓰일 수 있다. 본 연구에서는마이크로파를 이용하여 Diels-Alder 반응을 실시하고 열적으로 안정한 측사슬계 2차 비선형광학고분자를 합성하였다. 일반적인 수열반응을 통해 얻어진 고분자와 물리적, 열적, 광학적 특성을 비교 분석하였으며 마이크로파 가열을 활성화하기 위해 용매를 달리하고 이온성액제를 첨가하여 반응을 조절하였다. PAMID시리즈의 다양한 고분자를 합성하였으며 이중에서 PAMID-M2는 10분간 120W의 전력을 사용하여 얻어졌으며 이 때 사용한 용매는 이온성액제가 소량 첨가된 trichloroethane을 사용하였다. 얻어진PAMID-M2의 무게평균 분자량은 18,300이었으며 분포도는 1.3이었고 높은 유리전이온도 (123oC)를 나타냈다.

In this study, we successfully synthesized a nano-sized lanthanum-modified lead-titanate (PLT) powder with a perovskite structure using a high-energy mechanochemical process (MCP). In addition, the sintering behavior of synthesized PLT nanopowder was investigated and the sintering temperature that can make the full dense PLT specimen decreased to below by using powder as sintering agent. The pure PLT phase of perovskite structure was formed after MCP was conducted for 4 h and the average size of the particles was approximately 20 nm. After sintered at 1050 and , the relative density of PLT was about 93.84 and 95.78%, respectively. The density of PLT increased with adding and the specimen with the relative densitiy over 96% were fabricated below when 2 wt% of was added.

The benzophenone derivatives(4-CH3O-4'-NO2 and 3,4'-di-NO2) are synthesized by the Fridel-Craft acylation and the nitration method. Electrochemical redox potentials of the benzophenone derivatives (4-CH3O, H, 3-Cl, 3-NO2, 4-NO2, 4-CH3O-4'-NO2, 3,4'-di-NO2) are measured by using cyclic voltammometry. In the relationship of summing Hammett value and redox potential, we find a proportional constant(σ) that shows a good relation with an electrochemical property and a reactivity of the benzophenone derivatives. The benzophenone substituted with the electron donating groups(4-OCH3 and 4-OCH3-4'-NO2) are higher the energy in the LUMO level, then increasing a band-gap energy(Eg), their Egs are obtained as a 3.94 eV and 3.59 eV, respectively.

In chemistry, the study of sonochemistry is concerned with understanding the effect of sonic waves and wave properties on chemical systems. In the area of chemical kinetics, it has been observed that ultrasound can greatly enhance chemical reactivity in a number of systems by as much as a million-fold. Nano-technology is a super microscopic technology in which structures of 100 nanometers or smaller can be investigated. This technology has been used to develop TiO2 materials and TiO2 devices of that size. Thus far, electrochemistry methods and photochemistry methods have generally been used to create TiO2 nano-size particles. However, these methods are complicated and create pollutants as a by-product. In the present study, nano-scale silver particles (5 nm) were prepared in a sonochemistry method. Sonochemistry deals with mechanical energy that is provided by the collapse of cavitation bubbles that form in solutions during exposure to ultrasound. TiO2 powders 25 nm in size doped with Ag were formed using an ultrasonic sound technique. The experimental results showed the high possibility of removing pollution through the action of a photocatalyst. This powder synthesis technique can be considered as an environmentally friendly powder-forming processing owing to its energy saving characteristics.

Aluminum nitride (AlN) powders were prepared by the chemical vapor synthesis (CVS) process in the system. Aluminum chloride () as the starting material was gasified in the heating chamber of . Aluminum chloride gas transported to the furnace in atmosphere at the gas flow rate of 200-400ml/min. For samples synthesized between 700 and , the XRD peaks corresponding to AlN were comparatively sharp and also showed an improvement of crystallinity with increasing the reaction temperature. In additions, the average particle size of the AlN powders decreased from 250 to 40 nm, as the reaction temperature increased.

Nano-sized tungsten disulfide () powders were synthesized by chemical vapor condensation (CVC) process using tungsten carbonyl () as precursor and vaporized pure sulfur. Prior to the synthesis of tungsten disulfide nanoparticles, the pure tungsten nanoparticles were produced by same route to define the optimum synthesis parameters, which were then successfully applied to synthesize tungsten disulfide. The influence of experimental parameters on the phase and chemical composition as well as mean size of the particles for the produced pure tungsten and tungsten disulfide nanoparticles, were investigated

Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as . The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

Yttrium aluminum garnet (YAG) powders were synthesized via mechanochemical solid reaction using with three types of aluminum compounds. reacted mechanochemically with all A1 compounds and formed YAM (yttrium aluminum monoclinic), YAG and YAP (yttrium aluminum perovskite) phases depending on the starting materials. The ground samples containing showed the best reactivity, whereas the ground sample containing A100H, which had the largest surface area, exhibited pure YAG after calcination at . The sample containing Al had the least reactivity, producing YAP along with YAG at . The types and grinding characteristics of the starting materials and grinding time are believed to be important factors in the mechanochemical synthesis of YAG.

The nanostructured cerium oxide powders were synthesized by spray thermal decomposition process for the use as the raw materials of resistive oxygen sensor. The synthesis routes consisted of 1) spray drying of water based organic solution made from cerium nitrate hydrate () and 2) heat treatment of spray dried precursor powders at in air atmosphere to remove the volatile components and identically to oxidize the cerium component. The produced powders have shown the loose structure agglomerated with extremely fine cerium oxide particles with about 15 nm and very high specific surface area (). The oxygen sensitivity, n ( and the response time, measured at in the sample sintered at , were about 0.25 and 3 seconds, respectively, which had much higher performances than those known in micron or sized sensors.

Nanostructured and composite powders have been prepared by mechanochemical reaction from mixtures of Ti, BN, and powders. The raw materials have reacted to form a uniform mixture of TiN, and or depending on the amount of used in the starting mixtures, and the reaction proceeded through so-called mechanically activated self-sustaining reaction (MSR). Fine TiN and crystallites less than a few tens of nanometer were homogeneously dispersed in the amorphous or matrix after milling for 12 hours. These amorphous matrices became crystalline phases after annealing at high temperatures as expected, but the original microstructure did not change significantly