Estudo da adsorção de hidrogênio e sulfeto na superfície de paládio: aspectos experimentais (eletroquímica) e teóricos (ab initio e Teoria do Funcional da Densidade)

Abstract

Recebido em 5/4/00; aceito em 29/11/00 EXPERIMENTAL (ELECTROCHEMISTRY) AND THEORETICAL (AB INITIO AND DENSITY FUNCTIONAL THEORY) STUDIES OF HYDROGEN AND SULFIDE ADSORPTION ON PALLADIUM (100) SURFACE. The adsorption of H and S 2species on Pd (100) has been studied with ab initio, density-functional calculations and electrochemical methods. A cluster of five Pd atoms with a frozen geometry described the surface. The computational calculations were performed through the GAUSSIAN94 program, and the basis functions adapted to a pseudo-potential obtained by using the Generator Coordinate Method adapted to the this program. Using the cyclic voltammetry technique through a Model 283 Potentiostat/Galvanostat E.G.&G-PAR obtained the electrochemical results. The calculated chemisorption geometry has a Pd-H distance of 1.55Å, and the potential energy surface was calculated using the Becke3P86//(GCM/DFT/SBK) methodology. The adsorption of S 2ions on Pd surface obtained both through comparison between the experimental and theoretical results, at MP2 level, suggest a S 2absorption into the metallic cluster. The produced Pd-(S 2-) system was show to be very stable under the employed experimental conditions. The paper has shows the powerful aid of computational methods to interpret adsorption experimental data.