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Exploring computational materials for energy : from first principles to mesoscopic methodsPereira, Aline Olimpio January 2015 (has links)
Orientador: Prof. Dr. Caetano Rodrigues Miranda / Tese (doutorado) - Universidade Federal do ABC, Programa de Pós-Graduação em Nanociências e Materiais Avançados, 2015. / In this thesis, we explore computational materials science for energy technologies.
More specifically, a multiscale computational methodology ranging from atomistic to
mesoscopic methods was used to investigate the potential use of nanostructured materials
for applications in: (i) hydrogen and fuel cells, (ii) rechargeable batteries, and (iii) oil
recovery techniques.
First principles simulations based on the Density Functional Theory were successfully
employed to characterize and propose nanomaterials for hydrogen production and storage,
fuel cells, and battery technologies. It was possible to understand fundamental properties
that are essential to further development in these technologies, e. g. structural, electronic,
catalytic and kinetic properties. The structural, energetic and electronic properties
of layered metallic nanofilms of Pd, Pt and Au as catalysts for hydrogen and fuel
cell applications were investigated. We have shown that Pd and Pt nanofilms are
interesting systems, with improved catalytic activity for hydrogen, oxygen and ethanol.
The evaluation of the electronic structure of such nanofilms shows the existence of a linear
correlation between the d-band center and adsorption energies. The determination of such
trends represents a significative contribution to the design of new and improved catalysts,
since it is a valuable tool to predict the catalytic activity of nanofilms.
Significant breakthroughs were also obtained when applying first principles calculations
to battery technologies. The adsorption and di.usion properties of Li and Mg were
investigated in transition metal dichalcogenide inorganic nanotubes. A high ion mobility
is observed at the surface of MoS2 and WS2 nanotubes, which support the potential
application of the use of such systems as additive electrode materials for high-rate battery
applications.
By using classical molecular dynamics calculations, the structural and di.usion
properties of organic electrolytes could be determined and may help in the development
of rechargeable batteries. Our simulations have demonstrated that mixture of ethylene
carbonate and ethylmethyl carbonate present better di.usion properties as electrolyte in
lithium ion batteries, since it is possible to obtain a good degree of dissociation associated
to a good ionic conductivity.
xvi Abstract
In order to extent the nanoscale e.ects to the microscale, we also successfully propose
a hierarchical computational protocol that combines molecular dynamics and mesoscopic
lattice Boltzmann calculations. The e.ects of dispersed functionalized SiO2 nanoparticles
in brine to the oil recovery process in a covered clay pore structure is explored. Molecular
dynamics simulations have shown that the addition of functionalized nanoparticles to
the brine solution reduces the interfacial tension between oil and brine. Followed by
an increase of the contact angle. By mapping these results into lattice Boltzmann
parameters, the oil displacement process in hydrophilic pore models was investigated. Our
simulations indicate that the observed changes in the interfacial tension and wettability
by the inclusion of SiO2 nanoparticles indeed improve the oil recovery process in a
microscale, and seems to be a good alternative as injection fluids for enhanced oil recovery
techniques. Thus, our proposed hierarchical computational protocol that combines
molecular dynamics and lattice Boltzmann method simulations can be a versatile tool to
investigate the e.ects of the interfacial tension and wetting properties on fluid behavior
at both nano and micro scales.
Although it is clear that the search and development of new advanced materials
continues to be a key factor in energy technologies, the present thesis represent a significant
contribution to understand the fundamental phenomena underlying hydrogen production
and storage, fuel cells, batteries, and fossil fuel applications.
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