Adsorption and Reaction of C₂H₄ and O₂ on a Nanosized Gold Cluster: A Computational Study.

We have investigated the adsorption and reaction mechanisms of C2H4 and O2 catalyzed by a Au38 nanoparticle based on periodic density-functional theory (DFT) calculations. The configurations of the adsorption of C2H4/Au38, O2/Au38, and O/Au38 as well as the coadsorption of C2H4-O2/Au38 were predicted. The calculation results show that C2H4, O2, and O are preferably bound at top (T), bridge (B), and hexagonal (h) sites with adsorption energies of -0.66, -0.99, and -3.93 eV, respectively. The detailed reaction mechanisms for ethylene epoxidation on the Au38 nanoparticle has been illustrated using the nudged elastic band (NEB) method. The oxidation process takes place via the Langmuir-Hinshelwood (LH) mechanism to generate ethylene oxide and acetaldehyde. The overall reaction of C2H4 + O2 + Au38 → ethylene oxide + O/Au38 is exothermic by 2.20-2.40 eV whereas those are 3.03-3.08 eV for the production of acetaldehyde and O/Au38. The nature of the interaction between the adsorbate and gold nanocluster has been analyzed by the detailed electronic local density of states (LDOS) to understand the high catalytic activity of the gold nanoclusters.