Reações de adsorção e formação de vacâncias em nanotubos de MoS2

Abstract

Due to environmental restrictions that are increasingly severe, elimination of sulfur from petroleum feedstocks is necessary. MoS2 NT have several applications, though there is little information about the applicability of these materials in hydrorefining processes. DFT calculations were employed to predict the formation energy, Gibbs free energy, and energy barriers of the sulfur vacancy for pristine and Co-doped MoS2 nanotubes. In order to gain more insight about the accessibility of the catalytic sites, a group of small organosulfur molecules was studied by force-field-based molecular dynamics in which it was possible to confirm that these species are able to enter the nanotube channel, thus reaching a possible sulfur vacancy. DFT calculations were once again carried out to study the interaction between the guest organosulfur molecules and the sulfur vacancies, enabling the observation of possible chemisorption phenomena. The computational results demonstrated that the bending of the MoS2 nanosheet, compared to the flat monolayer, favors formation of the sulfur vacancy as well as the interaction between the studied guest molecules and the active site.