Effect of Sulfur Concentration on the Morphology of Carbon Nanofibers Produced from a Botanical Hydrocarbon

Carbon nanofibers (CNF) with diameters of 20–130 nm with different morphologies were obtained from a botanical hydrocarbon: Turpentine oil, using ferrocene as catalyst source and sulfur as a promoter by simple spray pyrolysis method at 1,000 °C. The influence of sulfur concentration on the morphology of the carbon nanofibers was investigated. SEM, TEM, Raman, TGA/DTA, and BET surface area were employed to characterize the as-prepared samples. TEM analysis confirms that as-prepared CNFs have a very sharp tip, bamboo shape, open end, hemispherical cap, pipe like morphology, and metal particle trapped inside the wide hollow core. It is observed that sulfur plays an important role to promote or inhibit the CNF growth. Addition of sulfur to the solution of ferrocene and turpentine oil mixture was found to be very effective in promoting the growth of CNF. Without addition of sulfur, carbonaceous product was very less and mainly soot was formed. At high concentration of sulfur inhibit the growth of CNFs. Hence the yield of CNFs was optimized for a given sulfur concentration

The effect of carbon nanofillers on the performance of electromechanical polyaniline-based composite actuators

Different types of crystalline carbon nanomaterials were used to reinforce polyaniline for use in electromechanical bilayer bending actuators. The objective is to analyze how the different graphitic structures of the nanocarbons affect and improve the in situ polymerized polyaniline composites and their subsequent actuator behavior. The nanocarbons investigated were multiwalled carbon nanotubes, nitrogen-doped carbon nanotubes, helical-ribbon carbon nanofibers and graphene oxide, each one presenting different shape and structural characteristics. Films of nanocarbon-PAni composite were tested in a liquid electrolyte cell system. Experimental design was used to select the type of nanocarbon filler and composite loadings, and yielded a good balance of electromechanical properties. Raman spectroscopy suggests good interaction between PAni and the nanocarbon fillers. Electron microscopy showed that graphene oxide dispersed the best, followed by multiwall carbon nanotubes, while nitrogen-doped nanotube composites showed dispersion problems and thus poor performance. Multiwall carbon nanotube composite actuators showed the best performance based on the combination of bending angle, bending velocity and maximum working cycles, while graphene oxide attained similarly good performance due to its best dispersion. This parallel testing of a broad set of nanocarbon fillers on PAni-composite actuators is unprecedented to the best of our knowledge and shows that the type and properties of the carbon nanomaterial are critical to the performance of electromechanical devices with other conditions remaining equal.JCGG is grateful to CONACYT (2008-2010) and University of Alicante (2010-2012) for scholarship support. YIVC and FJRM thank CONACYT (Mexico) for grants SEP-CB-106942 and SEP-CB-2008-107082, respectively, for the parts of this work performed in Mexico, and the Rede NANOBIOTEC-Brasil (Edital 04/CII-2008 CAPES/MEC), as well as FACEPE and UFPE for additional support for a visiting professor stay at UFPE. IMG and JAC acknowledge support from the University of Alicante, MINECO (CTQ2013-44213-R) and GVA (PROMETEOII/2014/007 and ISIC/2012/008)

Novel application for graphene oxide-based ionanofluids in flat plate solar thermal collectors

Abstract This study presents new ionanofluids (INF) composed of 1-ethyl-3-methylimidazolium acetate ionic liquid (IL) and graphene oxide (GO) nanoparticles which have been assessed for the first time in an experimental flat plate solar thermal collector (FPSC). For this purpose, four types of INFs were synthesized, maintaining a constant concentration of GO nanoparticles dispersed in different base fluids: ionic liquid (IL/GO), a mixture of ionic liquid and water in varying concentrations (IL-water (75–25)%/GO and IL-water (50–50)%/GO), and water (Water/GO). These four INFs were characterized and their thermophysical and physicochemical properties were determined. The results indicated a 37.4% improvement in efficiency and up to a 2.5-fold increase in temperature within the collector when the IL was applied exclusively as the base fluid, compared to water. Furthermore, IL/GO demonstrated excellent stability, showing no signs of deterioration or nanoparticle precipitation two years after preparation and testing. These findings suggest that INFs based on IL and GO nanoparticles significantly enhance the efficiency of FPSC, presenting a promising option for solar energy applications and opening a new research avenue for INFs in the production of domestic hot water

Production of Carbon Nanotubes from Polyethylene Pyrolysis Gas and Effect of Temperature

Carbon nanotubes (CNTs) were produced by catalytic chemical vapor deposition using, as carbon source, a mixture of hydrocarbons and hydrogen that simulates the effluent gases from pyrolysis of polyethylene (PE). An Fe/Al3O3 catalyst was used in a range of temperatures from 600 to 800 °C. Multiwall carbon nanotubes of 20 nm in diameter and length on the order of micrometers were obtained. Higher yields were observed at 650 °C, where no prior catalyst reduction was necessary. Transmission electron microscopy, X-ray diffraction, and Raman spectrometry show a higher crystalline quality at 750 °C, although the balance yield–quality indicates that 650 °C is a satisfactory temperature for producing CNTs at a reasonable cost, since no extra hydrogen is necessary for the process. In addition to this, the effluent gas from the process can be further used for energy production.The CTQ 2008-05520 project of the Spanish Ministry of Science and Innovation and Prometeo 2009/043/FEDER