Seho Cho

Effects of surface chemical properties of activated carbon modified by amino-fluorination for electric double-layer capacitor.

The surface of phenol-based activated carbon (AC) was seriatim amino-fluorinated with solution of ammonium hydroxide and hydrofluoric acid in varying ratio to fabricate electrode materials for use in an electric double-layer capacitor (EDLC). The specific capacitance of the amino-fluorinated AC-based EDLC was measured in a 1 M H(2)SO(4) electrolyte, in which it was observed that the specific capacitances increased from 215 to 389 Fg(-1) and 119 and 250 Fg(-1) with the current densities of 0.1 and 1.0 Ag(-1), respectively, in comparison with those of an untreated AC-based EDLC when the amino-fluorination was optimized via seriatim mixed solution of 7.43 mol L(-1) ammonium hydroxide and 2.06 mol L(-1) hydrofluoric acid. This enhancement of capacitance was attributed to the synergistic effects of an increased electrochemical activity due to the formation of surface N- and F-functional groups and increased, specific surface area, and mesopore volumes, all of which resulted from the amino-fluorination of the electrode material.

Mechanical and thermal properties of MWCNT-reinforced epoxy nanocomposites by vacuum assisted resin transfer molding

Multi-walled carbon nanotube (MWCNT)/epoxy composites are prepared by a vacuum as- sisted resin transfer molding (VARTM) method. The mechanical properties, fracture sur- face morphologies, and thermal stabilities of these nanocomposites are evaluated for epoxy resins with various amounts of MWCNTs. Composites consisting of different amounts of MWCNTs displayed an increase of the work of adhesion between the MWCNTs and the matrix, which improved both the tensile and impact strengths of the composites. The tensile and impact strengths of the MWCNT/epoxy composite improved by 59 and 562% with 0.3 phr of MWCNTs, respectively, compared to the epoxy composite without MWCNTs. Thermal stability of the 0.3 phr MWCNT/epoxy composite increased compared to other ep- oxy composites with MWCNTs. The enhancement of the mechanical and thermal properties of the MWCNT/epoxy nanocomposites is attributed to improved dispersibility and strong interfacial interaction between the MWCNTs and the epoxy in the composites prepared by VARTM.

Fabrication and Characterization of Porous Non-Woven Carbon Based Highly Sensitive Gas Sensors Derived by Magnesium Oxide

Nanoporous non-woven carbon fibers for a gas sensor were prepared from a pitch/polyacrylonitrile (PAN) mixed solution through an electrospinning process and their gas-sensing properties were investigated. In order to create nanoscale pores, magnesium oxide (MgO) powders were added as a pore-forming agent during the mixing of these carbon precursors. The prepared nanoporous carbon fibers derived from the MgO pore-forming agent were characterized by scanning electron microscopy (SEM), N2-adsorption isotherms, and a gassensing analysis. The SEM images showed that the MgO powders affected the viscosity of the pitch/PAN solution, which led to the production of beaded fibers. The specific surface area of carbon fibers increased from 2.0 to 763.2 m 2 /g when using this method. The template method therefore improved the porous structure, which allows for more efficient gas adsorp tion. The sensing ability and the response time for the NO gas adsorption were improved by the increased surface area and micropore fraction. In conclusion, the carbon fibers with high micropore fractions created through the use of MgO as a pore-forming agent exhibited improved NO gas sensitivity.