Martin Cinke

CO2 adsorption in single-walled carbon nanotubes

Abstract Adsorption of CO 2 on purified single-walled carbon nanotubes (SWNTs) has been studied in the temperature range of 0–200 °C and found to be mainly a physisorption process. The SWNTs adsorb nearly twice the volume of CO 2 compared to activated carbon. The experimental results yield a CO 2 heat of adsorption of 2303 J/mol (0.024 eV) in SWNTs. Our computational study yields a similar binding energy and shows that the CO 2 is physisorbed side-on to the nanotube.

Pore structure of raw and purified HiPco single-walled carbon nanotubes

Abstract Very high purity single-walled carbon nanotubes (SWNTs) were obtained from HiPco SWNT samples containing Fe particles by a two-step purification process. The raw and purified samples were characterized using high resolution transmission electron microscopy (HRTEM), Raman spectroscopy and thermogravimetric analysis (TGA). The purified sample consists of ∼0.4% Fe and the process does not seem to introduce any additional defects. The N 2 adsorption isotherm studies at 77 K reveal that the total surface area of the purified sample increases to 1587 m 2 /g from 567 m 2 /g for the raw material, which is the highest value reported for SWNTs.

Impregnation of Catalytic Metals in Single-Walled Carbon Nanotubes for Toxic Gas Conversion in Life Support System

Carbon nanotubes (CNTs) possess extraordinary properties such as high surface area, ordered chemical structure that allows functionalization, larger pore volume, and very narrow pore size distribution that have attracted considerable research attention from around the world since their discovery in 1991. The development and characterization of an original and innovative approach for the control and elimination of gaseous toxins using single walled carbon nanotubes (SWNTs) promise superior performance over conventional approaches due to the ability to direct the selective uptake of gaseous species based on their controlled pore size, increased adsorptive capacity due to their increased surface area and the effectiveness of carbon nanotubes as catalyst supports for gaseous conversion. We present our recent investigation of using SWNTs as catalytic supporting materials to impregnate metals, such as rhodium (Rh), palladium (Pd) and other catalysts. A protocol has been developed to oxidize the SWNTs first and then impregnate the Rh in aqueous rhodium chloride solution, according to unique surface properties of SWNTs. The Rh has been successfully impregnated in SWNTs. The Rh-SWNTs have been characterized by various techniques, such as TGA, XPS, TEM, and FTIR. The project is funded by a NASA Research Announcement Grant to find applications of single walled nanocarbons in eliminating toxic gas Contaminant in life support system. This knowledge will be utilized in the development of a prototype SWNT KO, gas purification system that would represent a significant step in the development of high efficiency systems capable of selectively removing specific gaseous for use in regenerative life support system for human exploration missions.

Development of Metal-impregnated Single Walled Carbon Nanotubes for Toxic Gas Contaminant Control in Advanced Life Support Systems

ABSTRACT The success of physico-chemical waste processing and resource recovery technologies for life support application depends partly on the ability of gas clean-up systems to efficiently remove trace contaminants generated during the process with minimal use of expendables. Highly purified metal-impregnated carbon nanotubes promise superior performance over conventional approaches to gas clean-up due to their ability to direct the selective uptake gaseous species based both on the nanotube’s controlled pore size, high surface area, and ordered chemical structure that allows functionalization and on the nanotube’s effectiveness as a catalyst support material for toxic contaminants removal. We present results on the purification of single walled carbon nanotubes (SWCNT) and efforts at metal impregnation of the SWCNT’s. INTRODUCTION CARBON MATERIALS ON SPACE HABITATS Carbon materials have long been used in environmental remediation and waste treatment for removal of toxic contaminants in both gaseous and liquid environments. On Space Station Mir, the air revitalization system included: (i) an expendable charcoal canister (weighing 6 Kg and having 1.3 Kg activated charcoal), (ii) two regenerable canisters (weighing 16 Kg each and having 7.4 Kg activated carbon each) and which are regenerated every 20 days, (iii) an ambient temperature catalyst containing 0.5 Kg of a precious metal catalyst, and Activated carbon has been extensively used due to a number of factors that include low-cost production and high surface area. However, some of the drawbacks to activated carbons are 1) non molecular defined chemical structure, 2) lack of specificity due to broad pore size distribution, 3) small pore volume and the associated low uptake weight for volatile gases, including NO, compounds. CARBON NAN0 TUBES (CNT)

Characterizations of Enriched Metallic Single-Walled Carbon Nanotubes in Polymer Composite

Using different processing conditions, we disperse the single-walled carbon nanotube (SWNT) into the polymethyl methacrylate (PMMA) to form composites. In the melt-blended sample, the SWNTs originally semiconducting - became predominantly metallic after dispersion into the melt-blended composite. The interaction of the PMMA and SWNT is investigated by the polarized Raman studies. The structure changes in the PMMA and SWNT shows that the anisotropic interactions are responsible for SWNT electronic density of states (DOS) changes. The increased metallic SWNT percentage is confirmed by the conductivity and dielectric constant measurements .