• Carbon letters
• /
• v.18
• /
• pp.30-36
• /
• 2016

Well-dispersed Ag₃VO₄ nanoparticles @polyacrylonitrile (PAN) nanofibers were synthesized by an easily controlled, template-free method as a photo-catalyst for the degradation of methylene blue. Their structural, optical, and photocatalytic properties have been studied by X-ray diffraction, transmission electron microscopy, field-emission scanning electron microscopy equipped with rapid energy dispersive analysis of X-ray, photoluminescence, and ultraviolet-visible spectroscopy. The characterization procedures revealed that the obtained material is PAN nanofibers decorated by Ag₃VO₄ nanoparticles. Photocatalytic degradation of methylene blue investigated in an aqueous solution under irradiation showed 99% degradation of the dye within 75 min. Finally, the antibacterial performance of Ag₃VO₄ nanoparticles @PAN composite nanofibers was experimentally verified by the destruction of Escherichia coli. These results suggest that the developed inexpensive and functional nanomaterials can serve as a non-precious catalyst for environmental applications.

• Journal of Sensor Science and Technology
• /
• v.24 no.6
• /
• pp.419-422
• /
• 2015

Pure and Mo-doped ZnO hollow nanofibers were prepared by single capillary electrospinning and their gas sensing characteristics toward 5 ppm ethanol, trimethylamine (TMA), CO and $H_2$ were investigated. The gas responses and responding kinetics were dependent upon sensing temperature and Mo doping. Mo-doped ZnO hollow nanofibers showed high response to 5 ppm TMA ($R_a/R_g=111.7$, $R_a$: resistance in air, $R_g$: resistance in gas) at $400^{\circ}C$, while the responses of pure ZnO hollow nanofibers was low ($R_a/R_g=47.1$). In addition, the doping of Mo enhanced selectivity toward TMA. The enhancement of gas response and selectivity to TMA by Mo doping to ZnO nanofibers was discussed in relation to the interaction between basic analyte gas and acidic additive materials.

• Journal of the Korean Society of Combustion
• /
• v.9 no.1
• /
• pp.18-24
• /
• 2004

Synthesis of carbon nanomaterials on a metal substrate by an ethylene fueled inverse diffusion flame was illustrated. Two stainless steel plates coated with $Ni(NO_3){_2}$ were folded with each other and used as a catalytic metal substrate. Carbon nanotubes and nanofibers with diameters of 20 - 60nm were found on the substrate. From the TEM-EDS analyses, most of the nanomaterials turned out to be Nicatalyzed. Carbon nanotubes were formed on the substrate in the region ranging from about 1,400K to 900K. The formation mechanisms of nanotubes and nanofibers were similar. The synthesis temperature of the nanofibers was lower than that of the nanotubes. The higher synthesis temperature of nanotubes might enhance the activity of the catalyst metal and produce more condensed carbons. The accumulated graphite layers led to form compartments to release the compressive stress in the layers. The growth of carbon nanotubes was bamboo-shaped showing compartments in the inside hollow. The distances between those compartments represented the growth rate that depended on the synthesis temperature.

• Journal of the Korean Electrochemical Society
• /
• v.24 no.1
• /
• pp.1-6
• /
• 2021

In this study, new morphology of NCA cathode material for lithium ion batteries was obtained through the electrospinning method. The prepared NCA nanofibers formed a nano-bush structure, and the primary particles were formed on the surface of the nanofibers. The embossing primary particles increased the surface area thus increasing the reactivity of lithium ions. The nano-bush structure could shorten the Li+ diffusion path and improve the Li+ diffusion coefficient. Scanning electron microscopy (SEM) revealed that the synthesized material consisted of nanofibers. The surface area of the nanofibers increased by primary particles was measured using atomic force microscopy (AFM). X-ray diffraction (XRD) analysis was carried out to determine the structure of the NCA nanofibers.

• Journal of the Korean Ceramic Society
• /
• v.40 no.12
• /
• pp.1150-1153
• /
• 2003

Carbon nanofilaments were formed on silicon substrate using microwave plasma-enhanced chemical vapor deposition method. The structures of carbon nanofilaments were identified as carbon nanotubes or carbon nanofibers. The formation of bamboo-like carbon nanotubes was initiated by the application of the bias voltage during the plasma reaction. The growth kinetics of bamboo-like carbon nanotubes increased with increasing the bias voltage. The growth direction of bamboo-like carbon nanotubes was vertical to the substrate.

• Proceedings of the Korean Institute of Surface Engineering Conference
• /
• 2012.11a
• /
• pp.90-90
• /
• 2012

Catechol moiety has enough reducing capability of reducing metal ions. Catechol-grafted polymer is chemically synthesized and electrospun into nanofibers as templates for metal nanostructures. The metal nanostructures are spontaneously generated on the catechol-grafted polymer nanofibers under ambient conditions.

• 한국신재생에너지학회:학술대회논문집
• /
• 2011.05a
• /
• pp.159.2-159.2
• /
• 2011

In this study, we prepared the activated graphite nanofibers (A-GNFs) via chemical activation with KOH reagent. The effect of A-GNFs on the surface and textural properties of Ni-loaded graphite nanofibers (Ni/GNFs) was investigated by X-ray diffraction (XRD), transmission electron microscope (TEM), and Brunauer-Emmett-Teller (BET). The textural properties of samples were investigated by $N_2$/77K adsorption isotherms. The electrochemical performances were investigated by cyclic voltammetry. As a results, the electrochemical performances of Ni/GNFs were improved with usage of A-GNFs. This could be interpreted by the high specific surface area and large total pore volume of the A-GNFs.

• Proceedings of the Polymer Society of Korea Conference
• /
• 2006.10a
• /
• pp.249-249
• /
• 2006

We have prepared an amphiphilic wedge-coil molecule consisting of a hydrophobic wedge-like segment and a hydrophilic poly(ethylene oxide) (PEO) segment. The wedge-coil block molecule self-assembles into cylindrical nanofibers in both polar as well as nonpolar solvents. Remarkably, the resulting nanofibers, as solvent polarity change from water to n-hexane, change from highly flexible coil-like to stiff rod-like characteristics. This dynamic switching in the stiffness of the nanofibers in response to solvent polarity is attributed to the structural inversion of cylindrical core from bulky dendritic segments with amorphous nature to crystallizable linear PEO segments.

• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.22 no.5
• /
• pp.218-222
• /
• 2012

FeNi alloy nanofibers have been prepared by an electrospinning process followed by air-calcination and H2 reduction to develop electromagnetic (EM) wave absorbers in the giga-hertz (GHz) frequency range. The thermal behavior and phase and morphology evolution in the synthetic processes were systematically investigated. Through the heat treatments of calcination and H2 reduction, as-spun PVP/FeNi precursor nanofiber has been stepwise transformed into nickel iron oxide and FeNi phases but the fibrous shape was maintained perfectly. The FeNi alloy nanofiber had the high aspect ratio and the average diameter of approximately 190 nm and primarily composed of FeNi nanocrystals with an average diameter of ~60 nm. The FeNi alloy nanofibers could be used for excellent EM wave absorbing materials in the GHz frequency range because the power loss of the FeNi nanofibers increased up to 20 GHz without a degradation and exhibited the superior EM wave absorption properties compared to commercial FeNi nanoparticles.

• Bulletin of the Korean Chemical Society
• /
• v.29 no.4
• /
• pp.777-781
• /
• 2008

In this work, silver nanoparticles-containing polyacrylonitrile (PAN) solutions in N,N-dimethylformamide (DMF) were electrospun to be webs consisting of nanofibers. The inputted voltage and PAN content in the solution were fixed at 15 kV and 10 wt.% in DMF with 10 cm of tip-to-collector distance (TCD). The PAN/Ag nanofiber webs were stabilized by oxidation at 250 ${^{\circ}C}$ for 2 h in air and carbonized at 1000 ${^{\circ}C}$ for 2 h in $N_2$. The resultant diameter distribution and morphologies of the nanofibers were evaluated by scanning electron microscope analysis. The electrochemical behaviors of the nanofiber webs were also observed by cyclic voltammetry tests. It was found that the presence of silver nanoparticles in carbon nanofiber webs led to the increase of specific capacitance and the decrease of fiber diameters.