Sun-Woo Choi

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SnO2-ZnO core-shell nanofibers were synthesized via a novel two-step process. First, SnO2 nanofibers were synthesized by electrospinning. In sequence, ZnO shell layers were deposited using atomic layer deposition on the electrospinning synthesized SnO2 nanofibers. To demonstrate the practical applications of the synthesized core-shell nanofibers, we(More)
We report a significant enhancement in the gas sensing properties of In(2)O(3) nanowires by functionalizing their surfaces with Pt nanoparticles. For Pt-functionalization, In(2)O(3)-Pt core-shell nanowires are synthesized by the sputtering deposition of Pt layers on bare In(2)O(3) nanowires. Next, continuous Pt shell layers are transformed into Pt(More)
We report a novel method for fabricating a highly sensitive chemical sensor based on a ZnO nanorod array that is epitaxially grown on a Pt-coated Si substrate, with a top–top electrode configuration. To practically test the device, its O 2 and NO 2 sensing properties were investigated. The gas sensing properties of this type of device suggest that the(More)
Networked SnO(2) nanowire sensors were achieved using the selective growth of SnO(2) nanowires and their tangling ability, particularly on on-chip V-groove structures, in an effort to overcome the disadvantages imposed on the conventional trench-structured SnO(2) nanowire sensors. The sensing performance of the V-groove-structured SnO(2) nanowire sensors(More)
γ-ray radiolysis is applied to synthesizing Pd nanodots on networked SnO(2) nanowires. The growth behavior of Pd nanodots is systematically investigated as a function of the precursor concentration, illumination intensity, and exposure time of the γ-rays. These factors greatly influence the growth behavior of the Pd nanodots. Selectively grown networked(More)
We report a dual functional sensing mechanism for ultrasensitive chemoresistive sensors based on SnO2-ZnO core-shell nanowires (C-S NWs) for detection of trace amounts of reducing gases. C-S NWs were synthesized by a two-step process, in which core SnO2 nanowires were first prepared by vapor-liquid-solid growth and ZnO shell layers were subsequently(More)
We report, and propose a mechanism for, the exceptional hydrogen gas (H2) sensing ability of ZnO nanofibers. In comparison to SnO2 nanofibers, ZnO nanofibers show outstanding H2 gas response and unmistakable H2 selectivity. Different from the reducing gas effect observed in SnO2 nanofibers, a semiconductor-to-metal transition that occurs in the presence of(More)
Networked ZnO nanowires were fabricated via a vapor-phase selective growth method. Pt nanoparticles were functionalized on the networked ZnO nanowires. In this study, for the functioanlization, γ-ray radiolysis was applied. By the method, Pt nanoparticles of - 10 nm in diameter were uniformly anchored on the surface of each ZnO nanowire. The sensing(More)
We propose a novel approach to improve the gas-sensing properties of n-type nanofibers (NFs) that involves creation of local p-n heterojunctions with p-type reduced graphene oxide (RGO) nanosheets (NSs). This work investigates the sensing behaviors of n-SnO2 NFs loaded with p-RGO NSs as a model system. n-SnO2 NFs demonstrated greatly improved gas-sensing(More)
A novel one-pot synthesis method for Pt-loaded SnO2 nanofibers is reported on the basis of the sol-gel and electrospinning-combined process. The ultraviolet illumination was used for in-situ growth of Pt nanoparticles in the electrospinning solution. The sensing capability of pure SnO2 nanofibers was significantly improved by loading Pt nanoparticles. The(More)