Surface Area Of Carbon Nanofibers Research Articles

Flexible electrospun carbon nanofibers/silicone composite films for electromagnetic interference shielding, electrothermal and photothermal applications

• Large-area flexible CNFFs are first prepared for EMI shielding material. • Stacking hot-pressing is suitable for large-scale preparation of AMS films. • The EMI shielding efficiency can reach ~ 100 dB with a low thickness of 0.6 mm. • The AMS films present excellent electro-thermal and photo-thermal performances. High-performance conductive films with electromagnetic interference (EMI) shielding, electrothermal, and photothermal properties are highly promising for the development of wearable devices, artificial intelligence, medical care, etc. However, designing such a film with flexibility and toughness remains a challenge. Here, a flexible and multi-responsive composite film for EMI shielding is proposed by coating large-area electrospun carbon nanofiber films (CNFFs) and silicone with an alternating multilayer structure (AMS). The optimal AMS film presents superior EMI shielding (the EMI shielding effectiveness can reach ~ 100 dB with a low thickness of 0.6 mm). Moreover, ultrafast electrothermal response and gratifyingly photothermal performances are also achieved, which can guarantee the normal functioning of AMS films in cold conditions. Furthermore, the outstanding flexibility can be still maintained even after 1000 continuous bending cycles, without worsening the EMI shielding, electrothermal, and photothermal performances. Such superior properties are attributed to the high electrical conductivity, the large specific surface area of carbon nanofibers (CNFs), and strong interface bonding strength, as well as the alternating multilayer structure. Considering the extraordinary performance and the facile preparation method, AMS films show tremendous potential in large-scale applications as advanced EMI protection materials.

Growth of carbon nanofibers by the catalytic decomposition of methane over Ni-Cu/Al2O3 catalyst

This paper shows that the catalytic decomposition of methane over Ni-Cu/Al2O3 catalyst at pressures of up to 5 bar leads to formation of carbon nanofibers of bamboo-like morphology with a “fish bone” structure with bridges inside the channel. When increasing the pressure, the change of textural characteristics of carbon nanofibers occurs. The surface area of carbon nanofibers increases from 130 to 166 m2/g, the volume of micropores grows from 0.005 to 0.014 cm3/g, the specific surface area of mesopores ranges from 117 to 137 m2/g at the pressure increase from 1 to 5 bar.

Investigation of the potential for utilization of sugarcane bagasse lignin for carbon fiber production: Thailand case study

Lignin is an attractive biomaterial to replace petroleum aromatics due to its intrinsic aromatic structure and availability. In Thailand, the sugar industry has potential as a source of around 7.5 million tons of lignin per annum. Sugarcane bagasse lignin was developed as a low-cost precursor in carbon fiber production to replace polyacrylonitrile, a petroleum-derived polymer using the electrospinning technique. A technical study and financial assessment of carbon fiber production feasibility from bagasse lignin at the laboratory scale were performed in parallel, and the Thai carbon fiber market was surveyed. Results showed that electrospun carbon nanofiber could be produced from a mixture of 25% lignin and 75% polyacrylonitrile with diameter of 171 nm. The surface area of carbon nanofiber produced from lignin-polyacrylonitrile mixture was higher than that of pure polyacrylonitrile. However, increasing lignin content in the mixture resulted in lower conductivity. Lignin-polyacrylonitrile carbon nanofiber obtained was appropriate for those where higher surface area was required rather than structural application. A market survey indicated increasing exploitation of carbon fiber in Thailand during the last 5 years even though there was no industrial production of carbon fiber due to technical and financial constraints. Both carbon nanofiber and lignin production costs at laboratory scale (12.4 $/g) were 27 times lower compared to commercial carbon nanofiber (343.4 $/g) available in a similar form. This price difference presents an opportunity to further development of carbon nanofiber for industrial application, although intensive research and development are still required.

Adsorption of Heavy Metal Ions by Carbon‐Nanofibers‐Blended Carbon Nanotubes

AbstractBy spinning different proportions of carbon nanotubes (CNTs) and polyacrylonitrile into filaments, discussing the structure of CNTs exposed on the surface of nanofibers after carbonization treatment at different temperatures, and the relationship between CNTs and pores in carbon nanofibers. Different pH, dosage, initial concentration of pollutants and adsorption time on the adsorption of Cr(VI) was studied on carbon nanofiber porous materials with carbon nanotubes. The results showed that the specific surface area of carbon nanofibers blended with CNTs increased to 37.627 m2/g and the pore volume reached 3.832cc/g. The porous adsorption material can reach the adsorption capacity of 25.17mgg−1 within 20 min. When the adsorption reached equilibrium, the adsorption capacity reached 76.62mgg−1.

Effect of Modification Techniques on Surface of Carbon Nanofiber as Catalyst Support

The intrinsic surface of carbon nanofiber (CNF) is important for supported catalyst preparation. The surface changes due to various techniques applied such as N2 thermal and HNO3 oxidation methods. The combination of different analyses is to observe the internal structure through Raman spectroscope, textural properties via N2 physisorption and morphology of CNF using transmission electron microscope or through quantification of oxygen containing groups by acid base titration. As results, an extension of residence time increases the amount of amorphous and damages the structure of mesoporous CNF texture unexpectedly. The change from hydrophobic to hydrophilic surface of CNF is due to the growing number of oxygen. The surface area of CNF by HNO3 treatment method produces 115.14m2/g which is higher than that of using thermal method.

Carbon nanofibers in catalytic membrane microreactors

Abstract In this study, we report on the fabrication and operation of new hybrid membrane microreactors for gas–liquid–solid (G–L–S) reactions. The presented reactors consist of porous stainless steel tubes onto which carbon nanofibers (CNFs) are grown as catalyst support, all encapsulated by a gas permeable coating. Such reactors benefit from a controlled G–L–S interface of a membrane reactor and high surface area of carbon nanofibers as catalyst support. Preparation steps such as porous stainless steel hollow fiber fabrication, CNF growth on the stainless steel surface, palladium catalyst immobilization and an outer gas permeable polymeric coating steps are presented. The fabricated microreactors have high surface area, mechanical strength and catalytic activity for nitrite reduction in water. Results proved high nitrite reduction performance of these reactors, even without the presence of palladium (Pd) or additional hydrogen (H 2) supply. Our results suggest intrinsic reductant properties and catalytic activity of the reactors, which make them very suitable for hydrogenation reactions.