Structural evolution of MoS2 supported gold nanoclusters under CO oxidation condition and the effect on reaction activity

Abstract

The understanding of structural evolution of metal nano-catalysts under real reaction condition is crucial for studying the catalytic properties. DFT calculations with van der Waals correction were performed to study the CO oxidation catalytic activity of Au nanoclusters with reconstruction due to CO adsorption. The global minimum structures of bare and MoS2 supported Aun (n = 1–20) nanoclusters, as well as Aun (n = 6, 12, 16 and 19)/MoS2 with different CO coverages, were obtained by minimum hopping algorithm to study the structural evolution. It is noted that three-dimensional Au19 supported on MoS2 transforms into two-dimensional structure for Au19(CO)6/MoS2 and quasi-2D structure for Au19(CO)12/MoS2 with CO coverage increasing. The stability of Aun(CO)m/MoS2 at 300 K was confirmed by ab initio molecular dynamics simulations, and the effect of CO adsorption on nanoclusters diffusion was also observed. Microkinetic analysis results indicated that the MoS2 support and structural reconstruction caused by CO adsorption both have remarkable effect on the CO oxidation activity, and the effect varies with Au nanocluster size.