Adsorción y oxidación de monóxido de carbono en una lamina de ß-grafino: Estudio teórico

AUTOR(ES)
FONTE

Matéria (Rio J.)

DATA DE PUBLICAÇÃO

19/07/2018

RESUMO

ABSTRACT This work presents a study, based on the Density functional theory (DFT), of the adsorption and oxidation of CO on a free platinum catalyst constituted from a sheet of Graphyne. Graphyne is a new allotrope of carbon, its structure is two-dimensional and is constituted by a monolayer of carbon atoms with sp-sp2 hybridization. Depending on the different ways to insert the carbon-carbon triple bond, three types of Graphyne can be distinguished: alpha, beta and gamma Graphyne. The structural, energetic and electronic properties have been studied, as well as the chemical reactivity to the adsorption and oxidation of carbon monoxide of a β-graphyne sheet. Therefore we propose a possible reaction route, using the Eley-Rideal mechanism. The calculations were performed using DFT, the functional hybrid B3PW91 and a 6-31 G basis for optimization of oxygen and carbon atoms was used. The transition state was obtained from the QST2 method, furthermore, vibrational frequencies were calculated to confirm the transition state and intrinsic reaction coordinates (IRC) to obtain the reaction mechanism. All calculations are performed according to the formalism of Gaussian09 program. Our results indicate that the coexistence of carbon with sp and sp2 hybridization in grafino promotes carbon atoms to perceive electropositive characteristics which favors the dissociation of oxygen and subsequent oxidation of CO. The study of the oxidation reaction through the Eley-Rideal mechanism shows that it is a concerted, exothermic and spontaneous process.

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