Browsing by Subject "fuel cell"

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Open Access
Adsorption and dissociation of hydrogen molecule on carbon nanotubes
(2004) Öztürk, Yavuz
Earlier, it has been suggested that carbon nanotubes can provide high storage capacity and other physical properties suitable for the fuel cell technologies. In this thesis we have investigated adsorption, desorption and dissociation of hydrogen molecule on the surface of the zigzag (8,0) single-wall carbon nanotube (SWNT) by carrying out extensive first-principles pseudopotential plane wave calculations within the Density Functional Theory (DFT). We found that while H2 molecule cannot be bound to the surface of bare SWNT, an elastic radial deformation leading to the elliptical deformation of the circular cross-section renders the physisorption of the molecule possible. Coadsorption of Li atom on the SWNT makes the similar effect, and hence enhances the physisorption. That an adsorbed H2 can be desorbed upon releasing the elastic radial strain is extremely convenient for the storage. In addition to that, we found that a Pt atom coadsorbed on the SWNT can form a strong chemisorption bond with a H2 molecule. If a single H2 molecule engages in interactions with more than one coadsorbed Pt atom at its close proximity it dissociates into single H atoms, which, in turn, make Pt-H bonds. The interaction between H2 and coadsorbed Pd atom is similar to Pt, but it is weaker. We believe that these findings clarify earlier controversial results related to the storage of H2 in carbon nanotubes, and makes important contributions to fuel cell technology.
Open Access
Hierarchical Electrospun Nanofibers for Energy Harvesting, Production and Environmental Remediation
(Royal Society of Chemistry, 2014) Kumar, P. S.; Sundaramurthy, J.; Sundarrajan, S.; Babu, V. J.; Singh, G.; Allakhverdiev, S. I.; Ramakrishna, S.
As the demand for energy is rapidly growing worldwide ahead of energy supply, there is an impulse need to develop alternative energy-harvesting technologies to sustain economic growth. Due to their unique optical and electrical properties, one-dimensional (1D) electrospun nanostructured materials are attractive for the construction of active energy harvesting devices such as photovoltaics, photocatalysts, hydrogen energy generators, and fuel cells. 1D nanostructures produced from electrospinning possess high chemical reactivity, high surface area, low density, as well as improved light absorption and dye adsorption compared to their bulk counterparts. So, research has been focused on the synthesis of 1D nanostructured fibers made from metal oxides, composites, dopants and surface modification. Furthermore, fine tuning these NFs has facilitated fast charge transfer and efficient charge separation for improved light absorption in photocatalytic and photovoltaic properties. The recent trend in exploring these electrospun nanostructures has been promising in-terms of reducing costs and enhancing the efficiency compared to conventional materials. This review article presents the synthesis of 1D nanostructured fibers made via electrospinning and their applications in photovoltaics, photocatalysis, hydrogen energy harvesting and fuel cells. The current challenges and future perspectives for electrospun nanomaterials are also reviewed.