Yonsei University · Engineering
Professor Dong Won Chun's research lab specializes in advanced materials synthesis and nanofabrication, with a focus on silicon-based micro/nanostructures, magnetic and catalytic materials for energy applications, and functional materials for biomedical sensing. The lab develops innovative techniques such as magnetically guided metal-assisted chemical etching (MACE) to enable precise, high-speed fabrication of vertically aligned Si micro- and nanostructures, while also exploring hydrogen storage materials like Mg–Fe hydrides and magnetic alloys such as FePtSn for high-performance permanent magnets. Their work bridges fundamental materials science with practical applications in renewable energy, medical diagnostics, and nanoelectronics.
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Herein, the bulk micromachining of Si by a magnetically guided metal-assisted chemical etching (MACE) process is demonstrated. To improve the etching performance of Si, a trilayer metal catalyst (Au/Fe/Au) is deposited on Si to obtain faster etching speed by a magnetic pulling force. An annealing process is performed on the catalyst to obtain rougher surface morphologies due to agglomeration and improve ferromagnetic properties, which increase the etching rate for magnetically guided MACE. By th
We report on the preconcentration-enhanced fast collection of myoglobin protein for the rapid detection of myocardial infarction. We use a one-dimensional micro/nanofluidic chip for electrokinetic preconcentration and demonstrate that the preconcentration factor of 1 ng/ml Alexa Fluor 488-labeled myoglobin is ∼1000 within 200 s, where the protein had a weak negative charge, thereby making it hard to perform electrokinetic trapping for neutral-like proteins. The potential feasibility with new ass
Abstract Herein, real‐time observations of dehydrogenation of a Mg 2 FeH 6 –MgH 2 composite by means of in situ transmission electron microscopy (TEM) with advanced spatial ( ≈ 0.8 Å) and temporal (25 frames s −1 ) resolution are reported. Careful control and systematic variations of the reaction temperature and electron dose rate enable detailed and direct visualization of the characteristic decomposition of Mg 2 FeH 6 into Mg and Fe, which occurs on the nanometer scale under optimal experiment
In this work, vertically aligned Si nanowire arrays were fabricated by magnetically guided metal-assisted directional chemical etching. Using an anodized aluminum oxide template as a shadow mask, nanoscale Ni dot arrays were fabricated on an Si wafer to serve as a mask to protect the Si during the etching. For the magnetically guided chemical etching, we deposited a tri-layer metal catalyst (Au/Fe/Au) in a Swiss-cheese configuration and etched the sample under the magnetic field to improve the d
Metal-assisted chemical etching (MACE) is widely used to fabricate micro-/nano-structured Si owing to its simplicity and cost-effectiveness. The technique of magnetically guided MACE, involving MACE with a tri-layer metal catalyst, was developed to improve etching speed as well as to adjust the etching direction using an external magnetic field. However, the controllability of the etching direction diminishes with an increase in the etching dimension, owing to the corrosion of Fe due to the etch
An attempt has been made in this study to incorporate an alloying element to lower the order-disorder transformation temperature of Fe–Pt alloy and the effect of Sn addition was investigated for this purpose. The coercivity of the FePtSn film is measured to be about 5000 Oe, whereas that of FePt film is several hundred Oe at the annealing temperature of 300 °C. Therefore, Sn addition is effective to promote the L10 ordering and reduce the ordering temperature of FePt alloy. Analysis of crystal s
Rational design of catalytic nanomaterials is essential for developing high-performance fuel cell catalysts. However, structural degradation and elemental dissolution during operation pose significant challenges to achieving long-term stability. Herein, the development of multi-grained NiPt nanocatalysts featuring an atomically ordered Ni<sub>3</sub>Pt<sub>5</sub> phase within intragrain is reported. Ultrasound-assisted synthesis facilitates atomic transposition by supplying sufficient diffusion
The excessed Ni will embed full-hesuler TiNi 2 Sb nanoprecipitates into the matrix, which can improve the thermoelectric performance by scattering low-energy carriers and phonons.
Abstract Radiation chemistry enables the synthesis of colloidal nanoparticles without chemical reducing agents, yielding metal nanoparticles via simple and direct processes. Aliphatic alcohols are widely used to promote the formation of nanoparticles in radiolytic synthesis by inhibiting the reoxidation of these metal nanoparticles by scavenging hydroxyl radicals. However, the role of the scavenger has been limited to simply accelerating the formation of the nanoparticles without altering their
An attempt is made in this study to employ vanadium containing chromium (CrV) alloy underlayer to control the microstructure and ultimately to facilitate the <i xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">in-situ</i> ordering of Fe-Pt thin film. CrV alloys with V contents ranging from 0 to 15 at% were investigated to evaluate their effects on the magnetic properties and structural modification of FePt thin film. Addition of V in Cr underlayer results
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