Papers by Author: Han Chang Shih

Abstract: Carbon nanotubes (CNTs) were functionalized using a simple method of heat treatment under oxygen atmosphere followed by an immersion in a tin nitrate aqueous solution. And well-dispersed SnOx nanodots were decorated on the surface of CNTs. X-ray photoelectron spectroscopy (XPS) analysis showed that the O/C ratio increases with oxygen-treated time. The distribution of carbon-containing functional groups on the CNTs surface, i.e., C−C, C−O, C=O, O−C=O, and π−π* shake up bonds can be identified and deconvoluted by a symmetrical Gauss function. The contact angle of H2O and CNTs is dependent on O/C ration. The relationships between the fraction of carbon-containing functional groups and various oxygen treatment times are also discussed.

Abstract: This work explores an estimation of adsorptive surface coverage for carbon tetrachloride onto different carbon nanofibers (CNFs). Two kinds of CNFs with various pore characteristics are fabricated by template-based and thermal chemical vapor deposition methods, respectively. The pore size distributions of these carbons, determined according to the density functional theory model, are found to vary with synthesis methods. The results of adsorption experiments show that CCl4 adsorption isotherms of these CNFs are of Langmuir-type model during the restricted pressure of 0–0.2 atm at 30°C. The surface coverage capable of adsorbing CCl4 molecules onto the CNFs can be determined based on the monolayer adsorption model. Interestingly, the CCl4 capacity of these CNFs does not proportionally increase with their specific surface area, and the CNFs with more micropore fraction facilitate the adsorptive surface coverage. This finding attributes to a fact that micropores in the CNFs have stronger adsorption energies, thus, become a major provider for carbon tetrachloride adsorption.

Abstract: Through self-assembly monolayer surface treatment, metal oxide nanoparticles uniformly dispersed onto carbon nanotubes (CNTs) surface are investigated. At first, oxidation treatment was performed to increase O/C ratio of CNTs surface at 250°C for 1 hr under an oxygen atmosphere. X-ray photoelectron spectroscopy (XPS) analysis shows that O/C ratio is a increasing function of oxidating time. Distribution of oxygen functional groups on CNTs surface, i.e., carboxyl, carbonyl, phenolic groups, can be identified and deconvoluted by a symmetrical Gauss function. Experiments indicate that heat time for 5hr can produce a greater O/C ratio on CNTs surface. It is observed that carboxyl groups acts an important role to link with metal ions via an ionic interaction, thus, forming a monolayer adsorption on CNTs surface. By heating the treated CNTs, a completely composite nanostructure is thus formed. In the present work, we successfully fabricate three kinds of nanoparticles including SnO2, and RuO2, with an average diameter of 5-10 nm coated on the CNTs.