The mechanism of methanol dehydrogenation on the PdAu(1 0 0) surface: A DFT study

Abstract

Density functional theory (DFT) was employed to investigate the mechanism of CH3OH dehydrogenation on the PdAu(1 0 0) surface. The adsorption of intermediates involved in the methanol dehydrogenation process was identified and all the elementary reactions were calculated. The route 3 “CH3OH → CH2OH → CHOH → CHO → CO” is determined as the most preferable pathway, of which the rate-limiting step is the dehydrogenation of CH3OH to CH2OH. PdAu has an enhanced catalytic performance towards MOR comparing to the monometallic Pd and Au systems. The strengthened adsorption of CH3OH and the decreased energy barrier of the rate-limiting step account for the enhanced activity, while the weaker CO adsorption contributes to the better anti-poisoning ability. On the PdAu(1 0 0) surface, Pd atoms play as the active sites while Au strengthens the activity and poisoning tolerance of the neighboring Pd. The synergistic effect of PdAu is explained by the d-band theory. The upshifted d-band center suggests that the Pd atoms on the PdAu(1 0 0) surface are more active than those on the Pd(1 0 0) surface. Our theoretical study reveals the mechanism of CH3OH dehydrogenation on the PdAu(1 0 0) surface, which is in favor of the further optimization of the promising non-platinum PdAu catalysts for DMFCs.