A influência dos elementos da primeira série de transição nas propriedades eletrônicas de aglomerados de paládio: um estudo baseado na Teoria do Funcional de Densidade (TFD)

• Autor(a) principal: Almeida, Ricardo de
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações da UERJ
• Texto Completo: http://www.bdtd.uerj.br/handle/1/15795
• topic: DFT; pd Clusters; first-row transition; ab Initio; DFT; aglomerado de paládio; primeira série de transição; ab initio; CNPQ::CIENCIAS EXATAS E DA TERRA::QUIMICA::QUIMICA ANALITICA::ANALISE DE TRACOS E QUIMICA AMBIENTAL

In the area of catalysis, interactions of small molecules such as H2, N2, O2, CO, NO etc. with metal clusters, have in their chemical adsorption key step in the catalytic activities. Palladium is among the most used metals in catalysts used in many heterogeneous catalytic processes. In this present work was carried out a series of calculations based on Density Functional Theory (DFT or DFT) employing the BP86 method / LANL2DZ / 6-311 + G (d, p) to study the adsorption of NO molecule was used as prototype to interact on the molecular clusters and pure palladium doped with transition metals of the first transition series (Pd3M and Pd9M). In this context, the scope of this study was to: (i) information about possible structural and electronic changes in palladium clusters when doped with the first series of transition metals (TM), (ii) to study the changes in the atom's behavior palladium in their respective pure clusters, compared to clusters doped with transition metals of the first series, (iii) to seek possible patterns of influence of MT in the properties of palladium clusters (eg energies of the frontier orbitals, giving electronic transfers and retrodoação, spin densities, orbital hybridizations responsible for links with adsorbents molecules etc). After performing the calculations based on DFT, the results show that, for the study of clusters containing four atoms was obtained direct correlation between the charge acquired by the metal M in the metal cluster and molecular orbital LUMO frontier calculated for Pd3M. This direct correlation does not hold when the palladium cluster size is increased from four to ten ring atoms. The adsorption energy made by the NO molecule correlates well with the LUMO energy regardless of the number of atoms and the geometry of the cluster and the nature of the dopant metal. The NO molecule adsorbs more favorably in Bridge mode, regardless of which metal is doping the Pd9M cluster. However, for the cluster Pd3M the adsorption mode depend on the nature of the dopant metal. The change in geometry and number of palladium atoms in the cluster causes changes in mood and energy of adsorption of NO adsorbent molecule. A further investigation to find other possible correlations between the properties of the first series metals and doped with palladium clusters them