A Density Functional Theory Study of the Water-Gas Shift Reaction Promoted by Neutral, Anionic, and Cationic Gold Dimers

作者：Wang Yingying; Zhang Dongju^*; Zhu Rongxiu; Zhang Changqiao; Liu Chengbu

来源：Journal of Physical Chemistry C, 2009, 113(15): 6215-6220.

DOI：10.1021/jp8108489

While nanoscale gold particles show exceptional catalytic activity toward the water-gas shift (WGS) reaction, not much is known about the detailed reaction mechanism and the influence of charge state of Au nanoparticles on the reactivity. We here report a systematic theoretical study by carrying out density functional theory calculations for the WGS reaction promoted by cationic, neutral, and anionic Au dimers, which represent three simplest prototypes of Au nanoparticles with different charge states. The reaction mechanism is explored along two possible entrances: one involves the complexes of the dimers with CO and the other is related to the complexes of the dimers with H(2)O. In all cases, it is found that the catalytic cycle proceeds via the formate mechanism and involves two sequential elementary steps: the rupture of the O-H bond in H(2)O and the formation of H(2) molecule. The calculated results show that the reaction mediated by Au(2)( ) is energetically most favorable compared to those promoted by Au(2) and Au(2)(-), indicating that the charge state of Au dimers plays an essential role for the catalyzed WGS. The present theoretical study rationalizes the early experimental findings well and enriches our understanding of the catalytic WGS by Au-based catalysts.

• 出版日期2009-4-16
• 单位山东大学