• 한국수소및신에너지학회논문집
• /
• 제24권3호
• /
• pp.193-199
• /
• 2013

In this work, thin film type Cu/ZnO nanostructure catalysts were fabricated by several synthetic routes in order to maximize the performance of the micro reforming system. For this work, various Cu/ZnO nanostructure catalysts could be synthesized by means of four approaches which are chemical vapor method, wet solution method and their hybrid method. The reforming performance of these as-synthetic catalysts was evaluated as compared to the conventional catalysts. Among the as-synthetic nanostructures, sphere type catalysts with specific surface of $18.6m^2/g$ showed the best performance of hydrogen production rate of 30ml/min at the feed rate of 0.2ml/min. This work will give the first insight on thin film type Cu/ZnO nanostructure catalyst for micro reforming system for hydrogen production of portable electronic systems.

• 한국재료학회지
• /
• 제25권11호
• /
• pp.622-629
• /
• 2015

Cu circuits were successfully fabricated on flexible PET(polyethylene terephthalate) substrates using wettability difference and electroless plating without an etching process. The wettability of Cu plating solution on PET was controlled by oxygen plasma treatment and $SiO_x$-DLC(silicon oxide containing diamond like carbon) coating by HMDSO(hexamethyldisiloxane) plasma. With an increase of the height of the nanostructures on the PET surface with the oxygen plasma treatment time, the wettability difference between the hydrophilicity and hydrophobicity increased, which allowed the etchless formation of a Cu pattern with high peel strength by selective Cu plating. When the height of the nanostructure was more than 1400 nm (60 min oxygen plasma treatment), the reduction of the critical impalement pressure with the decreasing density of the nanostructure caused the precipitation of copper in the hydrophobic region.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2016년도 제50회 동계 정기학술대회 초록집
• /
• pp.130-130
• /
• 2016

Bioinspired hierarchical nanostructures for self-cleaning s-tnwjurface and SERS substrates are investigated. The multi-level hierarchy is combined with CuO nanowire and additional nanoscale structures. CuO nanowire, which has extremely high aspect ratio, serves as a base structure of multi-level hierarchy and additional flower like structures are placed on the CuO nanowires. Since as-fabricated CuO nanostructures are hydrophilic, the surface is coated with perfluorooctyltrichlorosilane in order to change its wetting property to hydrophobic. While those CuO based nanostructures have a sufficient roughness for superhydrophobic characteristics, hierarchical nanoflowers on nanowire structures lead to a self-cleaning surface. Furthermore, flower like nanostructures provide reentrant curvatures, thus enabling oleophobic property. The surfaces has a repellency even for a tiny droplet (10 nL) of low surface tension liquids (~35 mN/m). On the on hands, nanoflowers provide many number of nanoscale gaps. After a thin layer of silver is deposited on the surface of CuO nanostructures, those nanoscale gaps act as hot-spot for surface enhanced Raman scattering (SERS). To analyze SERS enhancement of the surfaces, Raman shift is measured with varying molar density of 4-Mercaptopyridine from mM to pM. From these results, hierarchical CuO nanostructures are suitable for self-maintenance and cost effective SERS sensing applications.

• Bulletin of the Korean Chemical Society
• /
• 제31권8호
• /
• pp.2283-2288
• /
• 2010

Nanostructured copper compounds were grown by electrochemical anodization of copper foil in aqueous NaOH under varying conditions including electrolyte concentration, reaction temperature, current density, and reaction time. Their morphology and atomic composition were investigated by using SEM, TEM, XRD, EDS and XPS. At the conditions ([NaOH] = 1 M, $20^{\circ}C$, $2\;mA\;cm^{-2}$), wire-like orthorhombic $Cu(OH)_2$ nanobundles with an average width of 100 - 300 nm and length of $10\;{\mu}m$ were synthesized with the preferential [100] growth direction. Furthermore, when the concentration decreased to 0.5 M NaOH, the 1D nanobundle structure became narrower and longer without any change in compositions or crystalline structure. Side reaction pathways appeared to compete with the 1D nanostructure formation channels: the formation of CuO nanoleaves at $50^{\circ}C$ via the sequential dehydration of $Cu(OH)_2$, CuO/$Cu_2O$ aggregates in 4 M NaOH, and $Cu_2O$ nanoparticles and CuO nanosheets at lower current density.

• 한국표면공학회:학술대회논문집
• /
• 한국표면공학회 2014년도 추계학술대회 논문집
• /
• pp.112-113
• /
• 2014

The submicron-rods of $Cu_2O$ with diameters of 100-700 nm and lengths of $2-8{\mu}m$ were synthesized by radio frequency magnetron sputtering. The abundance of Cu species, which is modulated by the $Ar/O_2$ ratio during the sputtering process affect directly to the growths of the $Cu_2O$ branches on the bodies of the submicron-rods. Transmission electron microscopy and elemental mapping reveal that metallic Cu are existed on the heads of the $Cu_2O$ rods. The growth rate, catalyst phase and shape reveal that vapor-quasiliquid-solid was the growth mechanism of the formations of those structures.

• Korean Chemical Engineering Research
• /
• 제56권5호
• /
• pp.705-710
• /
• 2018

본 연구에서는 백금 나노입자가 분산된 산화구리 나노구조체 기반의 비효소적 글루코스 센서를 개발하였다. 3차원 구조의 산화구리 나노구조체는 hydrothermal method를 통해 Cu foil 위에 직접 합성되었으며, 합성된 나노구조체 표면위에 전기화학적 증착법으로 백금 나노입자들을 분산시켜 전극을 제작하였다. 준비된 전극 샘플의 표면 구조는 주사 전자 현미경(SEM)과 에너지분산형 분광기(EDS)을 이용하여 분석하였으며, 전기화학적 특성 및 센싱 성능은 알칼리 상태에서 시간대전류법 (CA)과 순환전압 전류법(CV)을 통하여 조사하였다. 개발된 비효소적 글루코스 센서는 산화구리 나노구조체와 백금 나노입자의 접목에 의한 시너지 효과 덕분에 높은 감도와 넓은 선형 구간, 빠른 감응 속도 등의 향상된 센싱 특성을 보였다.

• 공업화학
• /
• 제27권6호
• /
• pp.555-564
• /
• 2016

대기 중 이산화탄소의 재활용 기술과 재생에너지에 의한 물 분해 기술의 접목이 최근 가능해지면서 메탄올은 많은 관심을 받고 있다. 경제성이 유리하도록 메탄올 경제를 실현하기 위해서는 고활성 메탄올 합성 촉매를 제조하여야 하며, 이를 위해서는 논리적인 접근법이 필요하다. 공침법을 통해 제조하는 Cu/ZnO 기반의 촉매는 침전, 숙성, 여과, 세척, 건조, 소성, 환원 등의 복잡한 단계로 제조되며, 100년의 역사를 가지고 있음에도 불구하고 최근에야 침전 화학과 촉매 나노구조에 대한 기초적인 이해가 이루어지고 있다. 이에 본 고에서는 단계별로 합성 변수가 침전, 소성, 환원상태 물질의 물성에 미치는 영향에 대한 최근 결과들을 리뷰하고, 화학적 기억 효과라고 부르는 이들 물성들과 최종 촉매의 활성 사이의 관련성을 논의하였다. 제조 변수별 설명은 메탄올 합성을 위한 Cu/ZnO 기반 고활성 촉매를 제조하는 방법에 초점이 맞추어져 있다. 논의된 합성 전략은 공침법을 기반으로 하는 타 금속 또는 금속 산화물 담지 촉매의 제조에 활용 가능할 것으로 판단된다.

• 한국진공학회:학술대회논문집
• /
• 한국진공학회 2013년도 제45회 하계 정기학술대회 초록집
• /
• pp.249-249
• /
• 2013

Surface-enhanced Raman spectroscopy (SERS) is a sensitive approach to detect and to identify a variety of molecules. To enhance the Raman signal, optimization of the gap between nanostructures is quite important. One-dimensional materials such as nanowires, nanotubes, and nanograsses have great potential to be used in SERS due to their unique sizes and shape dependent characteristics. In this study we investigate a simple way to fabricate SERS substrates based on randomly grown copper oxide (CuO) nanowires. CuO nanograss is fabricated on pre-cleaned Cu foils. Cu oxidized in an ammonium ambient solution of 2.5 M NaOH and 0.1 M $(NH_4)_2S_2O_8$ at $4^{\circ}C$ for 10, 30, and 60 minutes. Then, Cu(OH)2 nanostructures are formed and dried at $180^{\circ}C$ for 2 h. With the drying process, the Cu(OH)2 nanostructure is transformed to CuO nanograss by dehydration reaction. CuO nanograss are grown randomly on Cu foil with the average length of 10 ${\mu}m$ and the average diameter of a 100 nm. CuO nanograsses are covered by Ag with various thicknesses from 10 to 30 nm using a thermal evaporator. Then, we immerse uncoated and Ag coated CuO nanowire samples of various oxidation times in a 0.001M methanol-based 4-mercaptopyridine (4-Mpy) in order to evaluate SERS enhancement. Raman shift and SERS enhancement are measured using a Raman spectrometer (Horiba, LabRAM ARAMIS Spectrometer) with the laser wavelength of 532 nm. Raman scattering is believed to be enhanced by the interaction between CuO nanograss and Ag island film. The gaps between Ag covered CuO nanograsses are diverse from <10 nm at the bottom to ~200 nm at the top of nanograsses. SERS signal are improved where the gaps are minimized to near 10s of nanometers. There are many spots that provide sufficiently narrow gap between the structures on randomly grown CuO nanograss surface. Then we may find optimal enhancement of Raman signal using the mapping data of average results. Fabrication of CuO nanograss based on a solution method is relatively simple and fast so this result can potentially provide a path toward cost effective fabrication of SERS substrate for sensing applications.

• 한국분말재료학회지
• /
• 제26권1호
• /
• pp.45-48
• /
• 2019

Quantum dots (QDs) are an attractive material for application in solar energy conversion devices because of their unique properties including facile band-gap tuning, a high-absorption coefficient, low-cost processing, and the potential multiple exciton generation effect. Recently, highly efficient quantum dot-sensitized solar cells (QDSCs) have been developed based on CdSe, PbS, CdS, and Cu-In-Se QDs. However, for the commercialization and wide application of these QDSCs, replacing the conventional rigid glass substrates with flexible substrates is required. Here, we demonstrate flexible CISe QDSCs based on vertically aligned $TiO_2$ nanotube (NT) electrodes. The highly uniform $TiO_2$ NT electrodes are prepared by two-step anodic oxidation. Using these flexible photoanodes and semi-transparent Pt counter electrodes, we fabricate the QDSCs and examine their photovoltaic properties. In particular, photovoltaic performances are optimized by controlling the nanostructure of $TiO_2$ NT electrodes.

• 한국표면공학회지
• /
• 제49권6호
• /
• pp.539-548
• /
• 2016

The non-noble 1D nanofibers(NFs) prepared by electrospinning and calcination method were used as oxygen evolution reaction (OER) electrocatalyst for water electrolysis. The electrospinning process and rate of solution composition was optimized to prepare uniform and non-beaded PVP polymer electrospun NFs. The diameter and morphology of PVP NFs changed in accordance with the viscosity and ion conductivity. The clean metal precursor contained electrospun fibers were synthesized via the optimized electrospinning process and solution composition. The calcined $CuCo_2O_4$ NFs catalyst showed higher activity and long-term cycle stability for OER compared with other $Co_3O_4$, $NiCo_2O$ NF catalysts. Furthermore, the $CuCo_2O_4$ NFs maintained the OER activity during long-term cycle test compared with commercial $CuCo_2O_4$ nanoparticle catalyst due to unique physicochemical and electrochemical properties by1D nanostructure.