Investigação &lt;i&gt;ab initio&lt;/i&gt; dos mecanismos de formação de nanoligas &lt;i&gt;core-shell&lt;/i&gt; com platina e metais de transição dos períodos 3&lt;i&gt;d&lt;/i&gt;, 4&lt;i&gt;d&lt;/i&gt; e 5&lt;i&gt;d&lt;/i&gt;

Justo, Stella Granatto

doi:10.11606/d.75.2018.tde-16012018-101637

Cited by 2 publications

(9 citation statements)

References 64 publications

(142 reference statements)

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“…Considering other theoretical studies, the deviations could be related to the different Source: Own study methodologies employed to calculate te property and technical details, such as the choice of computational parameters, slab construction and different vacuum regions; however, such deviations do not change the aforementioned periodic trends for the TM surfaces. Moreover, comparing our results for σ with the values from a previous study in our group, 136 which also employed PAW-PBE, we found excellent agreement, within 0.01 eV, except for Fe and Co surfaces, due to deviations from the magnetic moments.…”

Section: Surface Energysupporting

confidence: 81%

“…The choice of the 12.5 % multiplier is based on several previous studies of the properties of transition-metal bulks, surfaces and nanoclusters reported extensively in the literature 35,37,[133][134][135][136][137] This allowed the quick selection of well-converged computational parameters for the present study. Here, we selected some model systems to demonstrate the convergence of the properties with respect to the most important computational parameters.…”

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

“…Based on this demonstrative test and on the previous experience of the research group, the optimization of volume, a 3 0 , of crystals was performed using a cutoff energy of 2.0 times the recommended value (ENMAX) and a grid of k-points generated using a length of 50 for the subdivisions; this sampling of k-points is more rigorous than what is required for fcc Cu, but it allows good convergence for properties (such as the lattice parameter and total energy) for all bulks in our set, as verified in previous studies. 35,136 Differently from the optimization of the cell volume, for total energy calculations not involving stress tensor calculations, a multiplier of 1.125 was employed for ENMAX, as it is sufficient to obtain well converged results.…”

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

“…These choices are based on a large number of previous studies. 9,37,133,134,136,137 Notice that for the 1×1 slabs using large k-point meshes does not cause problems with the computational cost, since the system contains only a few atoms, this was applied for the study of the clean surfaces, Chapter 3.…”

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

“…Furthermore, the profile of σ for the 3d metals has some natural deviations that were addressed in the literature, 162 and attributed to magnetism. 163 The results obtained here for σ were compared to reference data from the literature, 136,143,160,[162][163][164]166 shown in Table 6. Although the profiles obtained for the surface energy versus the type of metal are correct, the deviations with respect to experimental data are significant, such deviations can be attributed to the clear distinction between the theoretical slab model and a real surface subjected to experimental conditions, as commented before.…”

Section: Surface Energymentioning

confidence: 99%

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>i<Ab Initio>/i< investigation of the adsorption of molecules, involved in carbon dioxide and glycerol utilization, on transition-metal substrates

Mendes¹

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This study was motivated by technologies involving the utilization of glycerol and carbon dioxide to obtain higher value products, which are economically promising and can benefit the environment. Carbon dioxide is a greenhouse gas, abundant in the atmosphere, that could be converted into monomers, fuels and other moieties, while glycerol is a polyol, accumulated as a byproduct in the production of biodiesel, that can be used to obtain other three-carbon alcohols. The aforementioned technologies could be developed by the use of transition-metal substrates as nanoparticles or extended surfaces to design catalysts with great control over properties, such as particle size, morphology and composition, which can be tuned towards optimal catalytic performance. Our study focused on adsorption, a pivotal step of the catalytic process. In this thesis, we present an extensive ab initio investigation, based on density functional theory, of the adsorption of carbon dioxide, glycerol and additional small model molecules on finite-sized and extended TM substrates. Concerning size effects, we found that the adsorption properties for physisorbed and chemisorbed CO 2 depended significantly on the particle size. For CO and H 2 , there was alternation of the most stable adsorption site for the various substrate sizes, which resulted in small size-induced oscillations of properties, while for H 2 O, the adsorption was almost independent of size effects. We also studied the adsorption of CO 2 on Pt-based nanoalloys and found that for systems containing metals with completely filled d-states, alloying with Pt facilitated the charge transfer to CO 2 ; on the other hand, for metals from groups 8, 9 and 10 of the periodic table, alloying with increasing Pt content either caused small effects on the adsorption properties or impaired charge transfer to CO 2 . Moreover, we explored several stable morphologies and chemical orderings and found that CO 2 tends to bend on low-coordinated and heterogeneous adsorption sites. Concerning glycerol and other three-carbon alcohols, we systematically studied the influence of OH groups on the adsorption on model surfaces and found that increasing the number of OH groups increases the adsorption strength, while changing their relative positions leads to similar adsorption strength, but with distinctions of other properties, such as bond stretching for the molecules, such trends were discussed in terms of the reactivities of the alcohols.

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Section: Surface Energysupporting

confidence: 81%

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

Section: Adjusting the Cutoff Energy For The Basis Set And Sampling The Brillouin Zonementioning

confidence: 99%

Section: Surface Energymentioning

confidence: 99%

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>i<Ab Initio>/i< investigation of the adsorption of molecules, involved in carbon dioxide and glycerol utilization, on transition-metal substrates

Mendes¹

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Estudos teóricos sobre difusão de prata metálica em óxidos ternários induzida por irradiação eletrônica

Jiupato¹

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Agradeço primeiramente ao Senhor Jesus,por todos os ensinamentos que aprendi e ainda aprenderei de acordo com a palavra de Deus e por ter me amparado nos momentos que tive durante o todo o percorrer da minha vida até este momento de defesa.Agradeço aos meus pais por toda paciência e influência, ensinamentos que me passaram para me tornar o que sou hoje, sem eles não teriam alcançado os meus objetivos e os meus sonhos.Agradeço especialmente a minha esposa Tayná Eloyane Barreto Rodrigues, por todo o carinho e atenção, pois me ensinou a ser mais compreensivo e paciente, mas principalmente, por insistir a minha vinda para Unicamp.Agradeço ao meu irmão Gabriel Rodrigues Pinheiro, que mesmo nas implicâncias me ensinou como ser uma pessoa melhor para com todos. Agradeço ao Prof. Miguel Angel San-Miguel pelo seu direcionamento e orientação ao longo desse período. Agradeço também aos meus colegas do grupo de pesquisa Unicamp Materials Simulation Lab: Cabral, Gabriella, Heitor e Otto. Em especial, ao Carlos, Felipe e ao Manoel, por toda a ajuda valiosa, que me foram essenciais para o desenvolvimento deste trabalho. Agradeço aos Professores Nelson Henrique Morgon e Leandro Martinez, pelas discussões e aperfeiçoamento do meu trabalho e para a minha formação. Aos Profs Drs. Edison Zacarias e Rafael Añez pelas discussões a respeito do meu trabalho e conselhos para apresentação. Agradeço ao Instituto de Química da Unicamp e a sua respectiva Comissão de Pós-Graduação (CPG-IQ), ao Centro de Computação CCJDR-IFGW e ao CDMF. Ao Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) pelo auxílio financeiro concedido em termos da bolsa de estudos de mestrado. Agradeço ao processo nº 2016/23891-6, 2013/07296-2, Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP), pelo financiamento concedido ao projeto temático ao qual o meu trabalho está vinculado. O presente trabalho foi realizado com apoio da Coordenação de Aperfeiçoamento de Pessoal de Nível Superior -Brasil (CAPES) -Código de Financiamento 001.

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Investigação <i>ab initio</i> dos mecanismos de formação de nanoligas <i>core-shell</i> com platina e metais de transição dos períodos 3<i>d</i>, 4<i>d</i> e 5<i>d</i>

Cited by 2 publications

References 64 publications

>i<Ab Initio>/i< investigation of the adsorption of molecules, involved in carbon dioxide and glycerol utilization, on transition-metal substrates

>i<Ab Initio>/i< investigation of the adsorption of molecules, involved in carbon dioxide and glycerol utilization, on transition-metal substrates

Estudos teóricos sobre difusão de prata metálica em óxidos ternários induzida por irradiação eletrônica

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