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.