• Macromolecular Research
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• v.17 no.8
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• pp.568-574
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• 2009

We investigated the sintering and consolidation phenomena of silver nanoparticles under various thermal treatment conditions when they were patterned by a contact printing technique on polyimide substrate films. The sintering of metastable silver nanoparticles commenced at 180 $^{\circ}C$, where the point necks were formed at the contact points of the nanoparticles to reduce the overall surface area and the overall surface energy. As the temperature was increased up to 250 $^{\circ}C$, silver atoms diffused from the grain boundaries at the intersections and continued to deposit on the interior surface of the pores, thereby filling up the remaining space. When the consolidation temperature exceeded 270 $^{\circ}C$, the capillary force between the spherical silver particles and polyimide flat surface induced the permanent deformation of the polyimide films, leaving crater-shaped indentation marks. The bonding force between the patterned silver metal and polyimide substrate was greatly increased by the heat treatment temperature and the mechanical interlocking by the metal particle indentation.

• Journal of Korean Society on Water Environment
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• v.26 no.4
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• pp.566-573
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• 2010

Nanotechnology has been applied to various fields in our life. Although there is a limitation of nanoparticle monitoring so far, it is expected that nanoparticles are widely distributed in environmental multimedia. Nanoparticle is known to be more toxic than its corresponding bulk material. For this reason, developed countries and international organizations are preparing for future regulation. To evaluate the safety of nanoparticles, nanotoxicity studies are internationally underway. In this study, we evaluated the research trends of ecotoxicity of nanoparticles in water environment. Test species include fish, water flea, and algae. Nanoecotoxicological studies are rapidly increasing and the experimental designs become more sophisticated. Physicochemical properties of nanoparticles should be measured and the ionization potential is important for metal-based nanoparticles. We analyzed the research trends based on the type of nanoparticles and test species. Also experimental aspects of nanoecotoxicology are considered.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.468-468
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• 2013

Self-assembled silver nanoparticles were synthesized on a graphene film to investigate plasmonic effect. Graphene was synthesized on glass substrate using chemical vapor deposition method and transfer process. Silver nanoparticles were formed using thermal evaporator and post-annealing process. The shape of silver nanoparticles was measured using a scanning electron microscopy. The resonance wavelength of plasmonic effect on graphene-silver nanoparticles was measured using transmittance spectra. The plasmon resonance wavelength was increased from 400 nm to 424 nm according to the lateral dimension of silver nanoparticles. Also we confirmed a strong plasmon effect form Raman spectra, which were measured on graphene-silver nanoparticles. The result shows that plasmon resonance wavelength could be controlled by lateral dimension of silver nanoparticles, and transparent conductive films based on plasmonic graphene could be developed.

• Journal of Powder Materials
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• v.27 no.2
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• pp.154-163
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• 2020

Fluorescent nanoparticles are characterized by their unique properties such as luminescence, optical transparency, and sensitivity to various chemical environments. For example, semiconductor nanocrystals (quantum dots), which are nanophosphors doped with transition metal or rare earth ions, can be classified as fluorescent nanoparticles. Tuning their optical and physico-chemical properties can be carried out by considering and taking advantage of nanoscale effects. For instance, quantum confinement causes a much higher fluorescence with nanoparticles than with their bulk counterparts. Recently, various types of fluorescent nanoparticles have been synthesized to extend their applications to other fields. In this study, State-of-the-art fluorescent nanoparticles are reviewed with emphasis on their analytical and anti-counterfeiting applications and synthesis processes. Moreover, the fundamental principles behind the exceptional properties of fluorescent nanoparticles are discussed.

• Advances in nano research
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• v.15 no.5
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• pp.441-449
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• 2023

Heavy metals, widely present in the environment, have become significant pollutants due to their excessive use in industries and technology. Their non-degradable nature poses a persistent environmental problem, leading to potential acute or chronic poisoning from prolonged exposure. Recent research has focused on separating heavy metals, particularly from industrial and mining sources. Industries such as metal plating, mining operations, tanning, wood and chipboard production, industrial paint and textile manufacturing, as well as oil refining, are major contributors of heavy metals in water sources. Therefore, removing heavy metals from water is crucial, especially for safe water supply in swimming and water sports. Iron oxide nanoparticles have proven to be highly effective adsorbents for water contaminants, and efforts have been made to enhance their efficiency and absorption capabilities through surface modifications. Nanoparticles synthesized using plant extracts can effectively bind with heavy metal ions by modifying the nanoparticle surface with plant components, thereby increasing the efficiency of heavy metal removal. This study focuses on removing lead from industrial wastewater using environmentally friendly, cost-effective iron nanoparticles synthesized with Genovese basil extract. The synthesis of nanoparticles is confirmed through analysis using Transmission Electron Microscope (TEM) and X-ray diffraction, validating their spherical shape and nanometer-scale dimensions. The method used in this study has a low detection limit of 0.031 ppm for measuring lead concentration, making it suitable for ensuring water safety in swimming and water sports.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.164-164
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• 2013

Among multicomponent nanostructures, hybrid nanocatalysts consisting of metal nanoparticle-semiconductor junctions offer an interesting platform to study the role of metal-oxide interfaces and hot electron flows in heterogeneous catalysis. In this study, we report that hot carriers generated upon photon absorption significantly impact the catalytic activity of CO oxidation. We found that Pt-CdSe-Pt nanodumbbells exhibited a higher turnover frequency by a factor of two during irradiation by light with energy higher than the bandgap of CdSe, while the turnover rate on bare Pt nanoparticles didn't depend on light irradiation. We also found that Pt nanoparticles deposited on a GaN substrate under light irradiation exhibit changes in catalytic activity of CO oxidation that depends on the type of doping of the GaN. We suppose that hot electrons are generated upon the absorption of photons by the semiconducting nanorods or substrates, whereafter the hot electrons are injected into the Pt nanoparticles, resulting in the change in catalytic activity. We discuss the possible mechanism for how hot carrier flows generated during light irradiation affect the catalytic activity of CO oxidation.

• Advances in materials Research
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• v.6 no.2
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• pp.129-153
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• 2017

Platinum is a transition metal that is very resistant to corrosion. It is used as catalyst for converting methyl alcohol to formaldehyde, as catalytic converter in cars, for hydrocracking of heavy oils, in Fuel Cell devices etc. Moreover, Platinum compounds are important ingredient for cancer chemotherapy drugs. The nano forms of Platinum due to its unique physico-chemical properties that are not found in its bulk counterpart, has been found to be of great importance in electronics, optoelectronics, enzyme immobilization etc. The stability of Platinum nanoparticles has supported its use for the development of efficient and durable proton exchange membrane Fuel Cells. The present review concentrates on the use of Platinum conjugated with various metal or compounds, to fabricate nanocomposites, to enhance the efficiency of Platinum nanoparticles. The recent advances in the synthesis methods of different Platinum-based nanocomposites and their applications in Fuel Cell, sensors, bioimaging, light emitting diode, dye sensitized solar cell, hydrogen generation and in biosystems has also been discussed.

• Proceedings of the Korea Crystallographic Association Conference
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• 2003.05a
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• pp.20-20
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• 2003

A new and simple method has been developed to synthesize highly crystalline and monodisperse maghemite (γ-Fe₂O₃) and zirconia (ZrO₂) nanocristallites. High temperature aging of metal-surfactant complex was founded to generate monodisperse nanoparticles, wherein the nuclei were prepared by the thermal decomposition of iron-oleate complex in case of iron oxide and nonhydrolytic sol-gel reaction in case of zirconia respectively. By varying the experimental conditions, in other words concentration of surfactants, kind of metal precursor, reaction temperature and so on, the diameter of spherical nanoparticles could be controlled at various size. The synthesized nanoparticles were characterized by electron diffraction, X-ray diffraction, and low- and high-resolution transmission electron microscope.

• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.82-88
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• 2014

A binary-coupled dipole approximation (BCDA) is described for designing metal nanoparticles with nonperiodic structures in one, two, and three dimensions. This method can be used to simulate the variation of near- and far-field properties through the interactions of metal nanoparticles. An advantage of this method is in its combination with the binary particle swarm optimization (BPSO) algorithm to find the best array of nanoparticles from all possible arrays. The BPSO algorithm has been used to design an array of plasmonic nanospheres to achieve maximum absorption, scattering, and extinction coefficient spectra. In BPSO, a swarm consists of a matrix with binary entries controlling the presence ('1') or the absence ('0') of nanospheres in the array. This approach is useful in optical applications such as solar cells, biosensors, and plasmonic nanoantennae, and optical cloaking.

• Composites Research
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• v.31 no.3
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• pp.94-98
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• 2018

Well-defined, monodispersed hollow ZnO nanoparticles were successfully synthesized by a facile one-pot solution method at room temperature. Hollow ZnO nanoparticles were fabricated using polystyrene nanoparticles as seed particles. The removal of core particles via solvent extraction yields hollow nanoparticles. The structures and morphologies of the obtained products were characterized with Fourier transform infrared (FT-IR), Thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), X-ray diffraction pattern (XRD) and Scanning electron microscopy (SEM). The formation mechanism of the hollow structure of the ZnO nanoparticles was also investigated. The technique developed here is expected to be useful in the preparation other metal oxides and hollow architectures.