Catalytic ethylene oxidation by Cu–Au core–shell nanoclusters: a computational study

Abstract

We have studied the catalytic activity of Cu–Au core–shell nanoclusters toward the ethylene oxidation based on periodic first-principles computations. The adsorption behaviors of O2 and C2H4 on the Cu–Au core–shell nanoclusters as well as the C2H4–O2 coadsorption were examined. We found that O2 and C2H4 are preferably bound at bridge (B) and top (T) sites with adsorption energies of − 2.09 and − 0.65 eV for Cu32–Au6 nanocluster and − 1.06 and − 0.62 eV for Au32–Cu6 nanocluster. The oxidation reaction occurs via the Langmuir–Hinshelwood (LH) mechanism which has been illustrated by employing the climbing image nudged elastic band method. The overall reaction of O2 + C2H4 → epoxide + O is exothermic by ~ 3.31 eV for Cu32–Au6 nanocluster and 2.17–2.26 eV for Au32–Cu6 nanocluster, while those are 3.76–4.24 eV and 2.91–2.73 eV for the generation of acetaldehyde. The Cu–Au core–shell nanoclusters, especially the hexagonal fcc(111)-like face of Cu32–Au6 and the square fcc(100)-like face of Au32–Cu6 core–shell nanoclusters, exhibit better catalytic properties and selectivity for the ethylene oxidation compared with the Cu and Au nanoparticles.