• Journal of the Korean Electrochemical Society
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• v.12 no.1
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• pp.47-53
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• 2009

In this study, highly ordered AAO (Anodic Aluminum Oxide) with nanopores was prepared by commercial grade Al substrate containing 3.5 wt.% impurities through two step anodizing method. Nanopores of prepared AAO arrays were used as templates for preparing nanofiber. $TiO_2$ was deposited by using DP (deposition-precipitation) method into AAO pores to grow nanofiber. Au particles were loaded on this $TiO_2$ nanofiber which was grown vertically. Prepared 2 wt.% $Au/TiO_2$ nanofiber was characterized by XRD, SEM and Raman. The crystal structure was analyzed by the XRD. SEM was used to observe pore size and pore wall thickness. Photocatalytic activity of co-oxidation was compared with $TiO_2$ and $Au/TiO_2$ nanofiber on AAO arrays.

• Bulletin of the Korean Chemical Society
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• v.32 no.5
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• pp.1715-1720
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• 2011

Nanoporous structured tin dioxide ($SnO_2$) is characterized and its application in the photocatalytic destruction of endocrine, Bisphenol A, is examined. Transmission electron microscopy (TEM) reveals irregularly shaped nanopores of size 2.0-4.5 nm. This corresponds to the result of an average nanopore distribution of 4.5 nm, as determined by Barret-Joyner-Halenda (BJH) plot from the isotherm curve. The photoluminescence (PL) curve, corresponding to the recombination between electron and hole, largely decreases in the $TiO_2$/nanoporous $SnO_2$ composite. Finally, a synergy effect between $TiO_2$ and porous $SnO_2$ is exhibited in photocatalysis: the photocatalytic destruction of Bisphenol A is improved by combining the nanoporous structured $SnO_2$ with $TiO_2$, and 75% decomposition of 10.0 ppm of Bisphenol A is achieved after 24 h.

• Journal of Microbiology and Biotechnology
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• v.26 no.9
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• pp.1505-1516
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• 2016

The detection of food pathogens is an important aspect of food safety. A range of detection systems and new analytical materials have been developed to achieve fast, sensitive, and accurate monitoring of target pathogens. In this review, we summarize the characteristics of selected nanomaterials and their applications in food, and place focus on the monitoring of biological and chemical contaminants in food. The unique optical and electrical properties of nanomaterials, such as gold nanoparticles, nanorods, quantum dots, carbon nanotubes, graphenes, nanopores, and polydiacetylene nanovesicles, are closely associated with their dimensions, which are comparable in scale to those of targeted biomolecules. Furthermore, their optical and electrical properties are highly dependent on local environments, which make them promising materials for sensor development. The specificity and selectivity of analytical nanomaterials for target contaminants can be achieved by combining them with various biological entities, such as antibodies, oligonucleotides, aptamers, membrane proteins, and biological ligands. Examples of nanomaterial-based analytical systems are presented together with their limitations and associated developmental issues.

• Bulletin of the Korean Chemical Society
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• v.28 no.12
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• pp.2481-2485
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• 2007

Spatially resolved, quantitative, non-destructive analysis using synchrotron x-ray reflectivity (XR) with subnano-scale resolution was successfully performed on the nanoporous organosilicate thin films for low dielectric applications. The structural information of porous thin films, which were prepared with polymethylsilsesquioxane and thermally labile 4-armed, star-shaped poly(ε-caprolactone) (PCL) composites, were characterized in terms of the laterally averaged electron density profile along with a film thickness as well as a total thickness. The thermal process used in this work caused to efficiently undergo sacrificial thermal degradation, generating closed nanopores in the film. The resultant nanoporous films became homogeneous, well-defined structure with a thin skin layer and low surface roughness. The average electron density of the calcined film reduced with increase of the initial porogen loading, and finally leaded to corresponding porosity ranged from 0 to 22.8% over the porogen loading range of 0-30 wt%. In addition to XR analysis, the surface and the inner structures of films are investigated and discussed with atomic force and scanning electron microscopy images.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.07b
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• pp.811-813
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• 2003

We investigated the electrical properties of self-assembled (4,4'-Di(ethynylphenyl)-2'-nitro-1-thioacetylbenzene), which has been well known as a conducting molecule having possible application to molecular level negative differential resistance(NDR)[1]. Generally, the phenomenon of NDR can be characterized by the decreasing current with the increasing voltage[2]. To deposit the SAM layer onto gold electrode, we transfer the prefabricated nanopores into a 1mM self-assembly molecules in THF solution. Au(111) substrates were prepared by ion beam sputtering method of gold onto the silicon wafer. As a result, we measured the voltage-current properties and confirmed the negative differential resistance properties of self-assembled organic thin film and measured, using Scanning Tunneling Microscopy(STM).

• Transactions on Electrical and Electronic Materials
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• v.16 no.4
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• pp.206-211
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• 2015

We investigated the formation of a nanopyramidal structure and fabricated nanotextured Si solar cells using an Ag metal-assisted chemical etching process. The nanopyramidal structure was formed on a Si flat surface and the nanotexturing process was performed on the p-type microtextured Si surface. The nanostructural formation shows a transition from nanopits and nanopores to nanowires with etching time. The nanotextured surfaces also showed the photoluminescence spectra with an enhanced intensity in the wavelength range of 1,100~1,250 nm. The photoreflectance of the nanotextured Si solar cells was strongly reduced in the wavelength range of 337~596 nm. However, the quantum efficiency is decreased in the nanotextured samples due to the increased nanosurface recombination. The nanotexturing process provides a better p-n junction impedance of the nanotextured cells, resulting in an enhanced shunt resistance and fill factor which in turn renders the possibility of the increased conversion efficiency.

• Macromolecular Research
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• v.16 no.5
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• pp.424-428
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• 2008

We prepared an ionic gel polymer electrolyte for dye-sensitized solar cells (DSSCs) without leakage problem. Triiodide compound (BTDI) was synthesized by the reaction of benzene tricarbonyl trichloride with diethylene glycol monotosylate and subsequent substitution of tosylate by iodide using NaI. Bisimidazole was prepared by the reaction of imidazole with the triethylene glycol ditosylate under strongly basic condition provided by NaH. BTDI and bisimidazole dissolved in an ionic liquid were injected into the cells and permeated into the $TiO_2$ nanopores. In situ crosslinking was then carried out by heating to form a network structure of poly(imidazolium iodide), thereby converting the ionic liquid electrolytes to a gel or a quasi-solid state. A monomer (BTDI and bisimidazole) concentration in the electrolytes of as low as 30 wt% was sufficient to form a stable gel type electrolyte. The DSSCs based on the gel polymer electrolytes showed a power conversion efficiency of as high as 1.15% with a short circuit current density of $5.69\;mAcm^{-2}$, an open circuit voltage of 0.525 V, and a fill factor of 0.43.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.2
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• pp.363-368
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• 2010

In this work, electrochemiluminescence (ECL) cell using nanocrysralline $TiO_2$ electrode and Ru(II) complex (Ru${(bpy)_3}^{2+}$) is fabricated for low-cost high-efficient energy conversion device application. The nanocrysrallme $TiO_2$ layer (${\sim}10{\mu}m$ thickness) with large surface area (${\sim}360m^2$/g) can largely inject electrons from nanoporous $TiO_2$ electrode and allows the oxidation/reduction of Ru(II) complex in the nanopores. The cell structure is composed of a glass/ F-doped $SnO_2$(FTO)/ porous $TiO_2$/ Ru(II) complex in acetonitrile/ FTO/ glass. The nanocrysralline $TiO_2$ layer is prepared using sol-gel combustion method. The ECL efficiency of the cell consisting of the porous $TiO_2$ layers was 250 cd/W, which was higher than that consisting of only FTO electrode (50cd/W). The nanoporous $TiO_2$ layers wwas effective for increasine ECL intensities.

• Bulletin of the Korean Chemical Society
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• v.34 no.8
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• pp.2271-2275
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• 2013

We report on the photoelectrochemical properties of partially reduced mesoporous titania thin films. The fabrication is achieved by synthesizing mesoporous titania thin films through the self-assembly of a titania precursor and a block copolymer, followed by aging and calcination, and heat-treatment under a $H_2$ (1 torr) environment. Depending on the temperature used for the reaction with $H_2$, the degree of the reduction (generation of oxygen vacancies) of the titania is controlled. The oxygen vacancies induce visible light absorption, and decrease of resistance while the mesoporosity is practically unaltered. The photoelectrochemical activity data on these films, by measuring their photocurrent-potential behavior in 1 M NaOH electrolyte under AM 1.5G 100 mW $cm^{-2}$ illumination, show that the three effects of the oxygen vacancies contribute to the enhancement of the photoelectrochemical properties of the mesoporous titania thin films. The results show that these oxygen deficient $TiO_2$ mesoporous thin films hold great promise for a solar hydrogen generation. Suggestions for the materials design for improved photoelectrochemical properties are made.

• Applied Microscopy
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• v.45 no.3
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• pp.107-114
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• 2015

Two-dimensional (2D) materials containing hole defects are a promising substitute for conventional nanopore membranes like silicon nitride. Hole defects on 2D materials, as atomically thin nanopores, have been used in nanopore devices, such as DNA sensor, gas sensor and purifier at lab-scale. For practical applications of 2D materials to nanopore devices, researches on characteristics of hole defects on graphene, hexagonal boron nitride and molybdenum disulfide have been conducted precisely using transmission electron microscope. Here, we summarized formation, features, structural preference and stability of hole defects on 2D materials with atomic-resolution transmission electron microscope images and theoretical calculations, emphasizing the future challenges in controlling the edge structures and stabilization of hole defects. Exploring the properties at the local structure of hole defects through in situ experiments is also the important issue for the fabrication of realistic 2D nanopore devices.