The catalytic mechanism of CO oxidation in AlAu6 clusters determined by density functional theory

Abstract

We present density functional calculations of O2 and CO adsorption on an AlAu6 cluster. It is found that in the AlAu6 cluster the active sites would be first occupied by coming O2 rather than CO due to a more negative binding energy of the former. Furthermore, the catalytic mechanisms of CO oxidation in AlAu6 clusters, which are based on a single CO molecule and double CO molecules, are discussed. This investigation reveals that the reaction of a single CO molecule with the AlAu6O2 complex has the lowest activation barrier (0.27 eV), which is 0.51 eV lower than that of the pure Au6− cluster. For the AlAu6O2(CO)2 complex, due to the structural distortion of the AlAu6 cluster, the activation barrier of the determination rate is higher by 0.53 eV than that of the AlAu6O2CO complex, which shows that the cooperation effect of the second CO molecule can go against CO oxidation. For the Al@Au6O2(CO)2 complex, the activation barrier of the determination rate is lower by 0.07 eV than the path of one CO molecule, which demonstrates that the cooperation effect of the second CO molecule can prompt CO oxidation.