Functionalized Carbon Nanofiber Research Articles

The effect of functionalized carbon nano-fiber (CNF) on gas separation performance of polysulfone (PSf) membranes

By mixing functionalized carbon nanofibers as inorganic substances with polysulfone (PSF) membrane, an extraordinary ability to separate CO2 from CH4 as well as N2 from O2 was developed in this study. The series of amine-functionalized-CNFs (F-CNFs)/PSf mixed matrix membrane with various F-CNFs contents (0–1.5wt.%) was prepared by solution casting method. In this paper, characterizations such as; morphology and crystalline structure have been conducted in details to investigate the structures and properties of mixed matrix membranes. The effects of F-CNF loading on the gas separation (O2, N2, CO2 and CH4) performance of the MMMs were evaluated using laboratory-scale gas separation apparatus. The MMMs exhibited higher CO2 permeability and perm-selectivity of CO2/CH4 due to higher interaction of amine groups on F-CNFs with CO2 as compared with the neat PSf membrane. The permeation measurement showed the CO2 and O2 permeability of about 3.57 and 1.58 (GPU), and CO2/CH4 and O2/N2 selectivity of about 7.7, 3.5, respectively, were obtained for MMM with 0.5wt.% F-CNFs loading. As a result, the developed membranes can be efficient for separating CO2 from CH4. The N2 selectivity was increased with addition of 0.5wt.% F-CNFs in the PSf casting solution, and then decreased with higher loading.

Localized surface grafting reactions on carbon nanofibers induced by gamma and e-beam irradiation

Electron beam and gamma-ray irradiation have potential application to modify the carbon fiber nanostructures in order to produce useful defects in the graphitic structure and create reactive sites. In this study, the methodology to functionalize carbon nanofiber (CNF), via a radiation process and using acrylic acid as a source of oxygen functional groups, was investigated. The samples were submitted to a direct grafting radiation process with electron beam and gamma-ray source. Several parameters were changed such as: acrylic acid concentration, radiation dose and percentage of inhibitor necessary to achieve functionalization, with higher percentage of oxygen functional groups on CNF surface, and better dispersion. The better results achieved were when mixing CNF in a solution of acrylic acid with 6% of inhibitor (FeSO4·7H2O) and irradiated at 100kGy. The samples were characterized by X-ray photoelectron spectroscopy and the surface composition (atomic%) showed a significant increase of oxygen content for the samples after irradiation. Also, the dispersion of the functionalized CNF in water was stable during months which may be a good indication that the functionalization process of CNF via ionizing radiation was successful.

Exceptional rate performance of functionalized carbon nanofiber anodes containing nanopores created by (Fe) sacrificial catalyst

Exceptional capacities and excellent rate performance have been achieved by anodes made from electrospun carbon nanofibers (CNFs) that possess synergies of (i) functionalization with carbonyl and carboxyl groups, (ii) presence of nanopores and (iii) embedded graphene layers. The Fe precursor incorporated into the polyacrylonitrile melt functions as both catalyst for graphitization and sacrificial phases. CNFs are functionalized and nanopores surrounded by graphene layers are simultaneously created during the chemical etching of Fe3C particles from the CNFs. The pore size and volume could be tuned by controlling the Fe precursor content. Both the functional groups and nanopores are accessible to Li ions, and the satisfactory electrical conductivity arising from graphitization allows fast transfer of electrons. Remarkable capacities of 983 and 318mAhg−1 are obtained when discharged at 100 and 3000mAg−1, respectively, along with excellent capacity retention after 100 cycles.

Polyamide‐12/Functionalized Carbon Nanofiber Composites: Evaluation of Thermal and Mechanical Properties

AbstractThis work aims at improving the interfacial bonding between polyamide‐12 and CNFs. CNFs were oxidized and dispersed in polyamide‐12 giving rise to polymer nanocomposites. The oxidation caused an increase in the specific surface area and structural defects of the fibers, as indicated by surface area and Fourier‐transform Raman spectroscopy. The nanocomposites exhibited improved thermal and thermo‐oxidative stabilities. The oxidized nanofibers had marginal effect on the crystallinity and crystallization of the polyamide‐12. An over‐proportional enhancement of stiffness due to the fibers could be achieved. In spite of these improvements the fiber/polymer adhesion should be further improved.magnified image

Pt–Ru nanoparticles supported PAMAM dendrimer functionalized carbon nanofiber composite catalysts and their application to methanol oxidation

Polyamidoamine (PAMAM) dendrimers has been anchored on functionalized carbon nanofibers (CNF) and supported Pt–Ru nanoparticles have been prepared with NaBH4 as a reducing agent. The samples were characterized by X-ray diffraction, scanning electron microscopy, and transmission electron microscopy (TEM) analysis. It was shown that Pt–Ru particles with small average size (2.6 nm) were uniformly dispersed on PAMAM/CNF composite support and displayed the characteristic diffraction peaks of Pt face-centered cubic structure. The electrocatalytic activities of the prepared-composites (20% Pt–Ru/PAMAM-CNF) were examined by using cyclic voltammetry for oxidation of methanol. The electrocatalytic activity of the CNF-based composite (20% Pt–Ru/PAMAM-CNF) electrode for methanol oxidation showed better performance than that of commercially available Johnson Mathey 20% Pt–Ru/C catalyst. The results imply that CNF-based PAMAM composite electrodes are excellent potential candidates for application in direct methanol fuel cells.

Ultrahigh-Surface-Area Metallic Electrodes by Templated Electroless Deposition on Functionalized Carbon Nanofiber Scaffolds

Electroless deposition of gold onto chemically functionalized carbon nanofibers leads to high-density nucleation of metal nanoparticles. These eventually form a highly textured coating, encapsulation the nanofibers. The gold-coated nanofibers show interfacial capacitances more than 10 times higher than those of the bare carbon nanofibers and 100 times larger than those of planar surfaces.