Estudo teórico via DFT da adsorção de glicerol sobre catalisadores de Pt e Pt-Sn

Abstract

Glycerol is considered as a good candidate for fuel cell application, however, in these systems a catalyst is required to oxidize it and its interaction with the catalyst is not fully understood. Thus, in this work, glycerol adsorption on the Pt (001) and Pt3Sn1 (001) surfaces was investigated through the Functional Theory of Density (DFT) using van der Waals correction for long range interactions and using the PBE-GGA functional in our calculations. The three structures for glycerol were constructed based on coordinates reported in the literature or designed and optimized, being the three different structures for this alcohol used in this work, which were placed on the metal surfaces in different positions. The metal structures were constructed as 2x2x1supercells from their unit cells. The glycerol on the surfaces configurations showed that the interaction of only one OH group is weaker than the interaction involving two or three OH groups. The data from projected state densities (PDOS) indicate that glycerol interactions with surfaces occur, mainly, via the oxygen atoms. Also the variations in charge densities confirm this fact. In addition, we verified that the use of van der Waals correction favored the configuration in which glycerol interacts with surfaces through both oxygen atoms of the terminal CH2OH groups, while without this correction the lower energy configuration contained the oxygen atom of the central CH2OH group being the closest to the surfaces.