• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2005년도 하계학술대회 논문집 Vol.6
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• pp.405-406
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• 2005

A theoretical investigation of the solid-phase mechanochemical synthesis of nano-sized target product on the basis of dilution of the initial powdered reagent mixture by another product of an exchange reaction is presented. On the basis of the proposed 3-mode particle size distribution in mechanically activated mixture, optimal molar ratios of the components in mixture are calculated, providing the occurrence of impact-friction contacts of reagent particles and excluding aggregation of the nanosized particles of the target reaction product. Derivation of kinetic equations for mechanochemical synthesis of nanoscale particles by the final product dilution method in the systems of exchange reactions is submitted. On the basis of obtained equations the necessary times of mechanical activation for complete course of mechanochemical reactions are designed. Kinetics of solid phase mechanosynthesis of nano-TlCl by dilution of initial (2NaCl + $Tl_2SO_4$) mixture with the exchange reaction product (diluent, $zNa_2SO_4$, $z=z^*=11.25$) was studied experimentally. Some peculiar features of the reaction mechanism were found. Parameters of the kinetic curve of nano-TlCl obtained experimentally were compared with those for the model reaction KBr + TlCl + zKCl = (z + 1) KCl + TlBr ($z=z_l^*=13.5$), and for the first time the value of mass transfer coefficient in a mechanochemical reactor with mobile milling balls was evaluated. Dynamics of the size change was followed for nanoparticle reaction product as a function of mechanical activation time.

• 한국재료학회지
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• 제30권5호
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• pp.239-245
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• 2020

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 20 W. The photocurrent density and the optimal photocurrent conversion efficiency obtained for the optimum ZnO nanorod array photoanode are 0.13 mA/㎠ 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.

• 한국표면공학회지
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• 제51권4호
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• pp.237-242
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• 2018

We report on the fabrication and photoelectrochemical (PEC) properties of a ZnO nanorod array structure as an efficient photoelectrode for hydrogen production from sunlight-driven water splitting. Vertically aligned ZnO nanorods were grown on an indium-tin-oxide-coated glass substrate via seed-mediated hydrothermal synthesis method with the use of a ZnO nanoparticle seed layer, which was formed by thermally oxidizing a sputtered Zn metal thin film. The structural and morphological properties of the synthesized ZnO nanorods were examined using X-ray diffraction and scanning electron microscopy, as well as Raman scattering. The PEC properties of the fabricated ZnO nanorod photoelectrode were evaluated by photocurrent conversion efficiency measurements under white light illumination. From the observed PEC current density versus voltage (J-V) behavior, the vertically aligned ZnO nanorod photoelectrode was found to exhibit a negligible dark current and high photocurrent density, e.g., $0.65mA/cm^2$ at 0.8 V vs Ag/AgCl in a 1 mM $Na_2SO_4$ electrolyte. In particular, a significant PEC performance was observed even at an applied bias of 0 V vs Ag/AgCl, which made the device self-powered.

• 한국분말재료학회지
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• 제28권5호
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• pp.429-434
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• 2021

Magnetic nanoparticles have a significant impact on the development of basic sciences and nanomedical, electronic, optical, and biotech industries. The development of magnetic structures with size homogeneity, magnetization, and particle dispersibility due to high-quality process development can broaden their utilization for separation analysis, structural color optics using surface modification, and energy/catalysts. In addition, magnetic nanoparticles simultaneously exhibit two properties: magnetic and plasmon resonance, which can be self-assembled and can improve signal sensitivity through plasmon resonance. This paper reports typical examples of the synthesis and properties of various magnetic nanoparticles, especially magnetoplasmonic nanoparticles developed in our laboratory over the past decade, and their optical, electrochemical, energy/catalytic, and bio-applications. In addition, the future value of magnetoplasmonic nanoparticles can be reevaluated by comparing them with that reported in the literature.

• 공업화학
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• 제31권6호
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• pp.697-700
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• 2020

본 연구에서는 석영 나노 결정의 합성과 특성 분석을 진행하였다. 비정질 실리카 나노 입자 전구체가 용해된 용액을 섭씨 250도 온도와 자가 압력의 온건한 열수 반응 하에서 석영 나노 결정을 성공적으로 합성하였다. 합성된 나노 결정의 화학적 조성과 구조 분석을 시행하였다. 알파 석영의 특징적인 고결정질 상의 나노 구조를 가지는 석영 나노 결정의 평균 크기는 반응 시간에 따라 407.5 에서 826.2 nm까지 비교적 좁은 범위에서 조정될 수 있음을 발견하였다. 본 연구를 통해 발견된 석영 나노 입자는 광전자, 센서, 및 충전식 배터리 소자의 기술 응용에 매우 중요한 잠재적 용도가 있을 것으로 사료된다.

• Korean Chemical Engineering Research
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• 제59권1호
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• pp.112-117
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• 2021

본 연구에서는 생물학적 공유결합인 다이타이로신 결합을 모방하여 비가역적 공유결합을 기반으로 한 펩타이드의 자기조립 방법을 연구하였다. 고밀도의 다이타이로신 결합을 달성하기 위해 Tyr-Tyr-Leu-Tyr-Tyr (YYLYY) 의 서열을 갖는 펩타이드 단량체를 선택하였다. 다이타이로신 결합으로 자기조립 된 펩타이드 나노입자는 가시광선 하에서 Ru(BPY)3Cl2 촉매를 사용하여 단일공정 광가교를 통해 합성되었다. 펩타이드 나노 입자의 크기에 대한 각 성분의 농도 효과는 동적 광산란, UV-Vis 분광법 및 투과 전자 현미경을 사용하여 확인하였다. 이를 통해 130 nm~350 nm범위의 펩타이드 나노입자의 크기별 최적의 합성 조건을 제시하였다.

• 한국표면공학회지
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• 제56권4호
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• pp.219-226
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• 2023

Utilizing low-dimensional structures of oxide semiconductors is a promising approach to fabricate relevant gas sensors by means of potential enhancement in surface-to-volume ratios of their sensing materials. In this work, vertically aligned cupric oxide (CuO) nanorods are successfully synthesized on a transparent glass substrate via seed-mediated hydrothermal synthesis method with the use of a CuO nanoparticle seed layer, which is formed by thermally oxidizing a sputtered Cu metal film. Structural and optical characterization by x-ray diffraction (XRD), scanning electron microscopy (SEM), and Raman spectroscopy reveals the successful preparation of the CuO nanorods array of the single monoclinic tenorite crystalline phase. From gas sensing measurements for the nitrogen monoxide (NO) gas, the vertically aligned CuO nanorod array is observed to have a highly responsive sensitivity to NO gas at relatively low concentrations and operating temperatures, especially showing a high maximum sensitivity to NO at 200 ℃ and a low NO detection limit of 2 ppm in dry air. These results along with a facile fabrication process demonstrate that the CuO nanorods synthesized on a transparent glass substrate are very promising for low-cost and high-performance NO gas sensors.

• 마이크로전자및패키징학회지
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• 제19권4호
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• pp.25-31
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• 2012

Tin(II) acetate 전구체를 사용한 습식 환원 합성법으로 나노입자를 제조하는 공정에서 친환경 환원제(슈거) 및 캡핑제(젤라틴)를 사용하여 합성 조건 및 합성 시간에 따른 주석 나노입자의 합성 특성을 분석하였다. 글루코스 환원제를 사용하여 $70-110^{\circ}C$의 온도에서 합성 시 불규칙한 사슬 형태로 군집체를 이루면서 배열된 환원 나노입자들이 관찰되었다. FFT 패턴 분석으로부터 이러한 나노입자들은 $SnO_2$ 상으로 분석되었다. 수크로오스 환원제로 사용하여 $110^{\circ}C$에서 합성을 실시한 경우에서는 3시간의 합성 시간에서 평균 약 10 nm급의 미세한 구형 나노입자들을 형성시킬 수 있었으나, 합성 시간을 9시간으로 증가시킨 경우에서는 불규칙하게 뭉친 나노입자들 외에도 사슬 형태의 나노입자 군집체들이 국부적으로 형성되는 거동이 관찰되었다. 그러나 $130^{\circ}C$ 합성 시에는 사슬 형태의 나노입자 군집체들만을 관찰할 수 있었다. 그 결과 구형의 나노입자는 순수 Sn 상으로, 사슬 형태 나노입자 군집체들은 $SnO_2$ 상으로 각각 분석되었다.

• ETRI Journal
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• 제26권3호
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• pp.252-256
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• 2004

We formed silver nanocrystallites by the thermal decomposition of a $Ag^{+1}$-oleate complex, which was prepared by a reaction with $AgNO_{3}$ and sodium oleate in a water solution. The resulting monodispersed silver nanocrystallites were produced by controlling the temperature (290$^{\circ}$C). Transmission electron microscopic (TEM) images of the particles showed a 2-dimensional assembly of the particles with a diameter of $9.5{\pm}0.7nm$, demonstrating the uniformity of these nanocrystallites. An energy-dispersive X-ray (EDX) spectrum and X-ray diffraction (XRD) peaks of the nanocrystallites showed the highly crystalline nature of the silver structure. We analyzed the decomposition of the $Ag^{+1}$-oleate complex using a Thermo Gravimetric Analyzer (TGA) and observed the crystallization process using XRD.

• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2592-2596
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• 2012

Cysteine capped silver nanoparticles (Cys-AgNPs) have been synthesized by employing electrochemically active biofilm (EAB), $AgNO_3$ as precursor and sodium acetate as electron donor in aqueous solution at $30^{\circ}C$. Cys-AgNPs of 5-10 nm were synthesized and characterized by UV-Vis, FT-IR, XRD and TEM. Capping of the silver nanoparticles with cysteine provides stability to nanoparticles by a thiolate bond between the amino acid and the nanoparticle surface and hydrogen bonding among the Cys-AgNPs. In addition, the antibacterial effects of as-synthesized Cys-AgNPs have been tested against two pathogenic bacteria Escherichia coli (O157:H7) and Pseudomonas aeruginosa (PAO1). The results demonstrate that the as-synthesized Cys-AgNPs can proficiently inhibit the growth and multiplication of E. coli and P. aeruginosa.