Byungrak Park

Robust superhydrophilic/hydrophobic surface based on self-aggregated Al2O3 nanowires by single-step anodization and self-assembly method.

Superhydrophilic and superhydrophobic surfaces were studied with an eye to industrial applications and use as research tools. Conventional methods involve complex and time-consuming processes and cannot feasibly produce large-area three-dimensional surfaces. Here, we report robust and large-area alumina nanowire structures with superhydrophobic or superhydrophilic properties, generated by an inexpensive single-step anodization process that can routinely create arbitrary three-dimensional shapes. This process is expected to open up diverse applications.

Improving the tensile strength of carbon nanotube yarn via one-step double [2+1] cycloadditions

The tensile strength of a CNT yarn was improved through simple one-step double [2+1] cycloaddition reactions that crosslinked the constituent CNTs using a polyethylene glycol (PEG)-diazide crosslinker. The FT-IR spectrum confirmed that the azide groups in the PEG-diazide were converted into aziridine rings, indicating that the cycloaddition reaction was successful. The generation of crosslinked CNTs was also supported by the observation of N1s peak in the XPS spectrum and the increased thermal stability of the material, as observed by TGA. The tensile strength of the CNT yarn was increased from 0.2GPa to 1.4GPa after the crosslinking reaction when twisted at 4000 twists/ meter. The appropriate selection of the crosslinker may further optimize the CNT yarn crosslinking reaction. The simplicity of this one-step crosslinking reaction provides an economical approach to the mass production of high-strength CNT yarns.

Silicon-based Floating-body Synaptic Transistor

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A large-scale water-harvesting device with β-Al(OH)3 microcone arrays by simple hydrothermal synthesis

As the scarcity of fresh water emerges as a major global problem, fog-water harvesting is considered as a sustainable method for obtaining water resources. Although water-harvesting technologies based on special wetting surfaces have attracted considerable interest because of their high efficiency, many problems remain, including high cost and difficulties in the fabrication of special wetting surfaces. Here we report a novel approach to fabricate conical microstructures on aluminum substrates using a cost-effective and scalable hydrothermal synthesis method. Due to their morphological features, the microcone surfaces exhibit extremely high wettability and excellent water-collection capacity. Furthermore, we suggest a practical water-harvesting device that allows an effective and sustainable way to collect fresh water from moist air and has enhanced adaptability to environmental conditions. These features enable us to develop a highly promising water-harvesting system for overcoming problems associated with water shortage.