Steel was anodized in 10 M NaOH to enhance its surface texture and internal surface area for application as an electrode in supercapacitors. A mechanism was proposed for the anodization process. Field-emission gun scanning electron microscopy (FEGSEM) studies of anodized steel revealed that it contains a highly porous sponge like structure ideal for supercapacitor electrodes. X-ray photoelectron spectroscopy (XPS) measurements showed that the surface of the anodized steel was Fe2O3, whereas X-ray diffraction (XRD) measurements indicated that the bulk remained as metallic Fe. The supercapacitor performance of the anodized steel was tested in 1 M NaOH and a capacitance of 18 mF cm(-2) was obtained. Cyclic voltammetry measurements showed that there was a large psueudocapacitive contribution which was due to oxidation of Fe to Fe(OH)2 and then further oxidation to FeOOH, and the respective reduction of these species back to metallic Fe. These redox processes were found to be remarkably reversible as the electrode showed no loss in capacitance after 10000 cycles. The results demonstrate that anodization of steel is a suitable method to produce high-surface-area electrodes for supercapacitors with excellent cycling lifetime.
Carbon nanotubes (CNTs) are grown on to steel substrates by aerosol-assisted chemical vapor deposition using ferrocene in ethanol as the carbon feedstock. The CNTs adopted a highly entangled morphology. Elemental analysis indicates that the main source of carbon for CNT growth is from the cyclopentadiene rings in ferrocene rather than the ethanol solvent. The CNT-coated steel substrates are evaluated for their performance as supercapacitor electrodes. The electrodes exhibit a high geometric capacitance of 3.4 mF cm À2 which is due to the high internal surface area, but a relatively low specific capacitance of 0.34 F g À1 .
Carbon emissions from industrial sources are of major global concern, especially contributions from the steel manufacturing process which accounts for the majority of emissions. Typical blast furnace gases consist of CO 2 (20-25%), CO (20-25%), H 2 (3-5%) and N 2 (40-50%) and trace amounts of other gases. It is demonstrated that gas mixtures with these compositions can be used at atmospheric pressure to grow carbon nanotubes (CNTs) by chemical vapor deposition (CVD) on to steel substrates, which act as catalysts for CNT growth. Computational modelling was used to investigate the CNT growth conditions inside the CVD chamber. The results show that industrial waste pollutant gases can be used to manufacture materials with significant commercial value, in this case CNTs.
In the lights of the steel industry contributing most to carbon emissions (CO2 greenhouse gases), carbon nanotubes (CNTs) are grown by chemical vapor deposition (CVD) on steel substrates which act as catalysts for the CNT growth.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.