Adsorption and Reaction of C<sub>2</sub>H<sub>4</sub> and O<sub>2</sub> on a Nanosized Gold Cluster: A Computational Study

2015-08-06T00:00:00Z (GMT) by Chen-Chi Lee Hsin-Tsung Chen
We have investigated the adsorption and reaction mechanisms of C<sub>2</sub>H<sub>4</sub> and O<sub>2</sub> catalyzed by a Au<sub>38</sub> nanoparticle based on periodic density-functional theory (DFT) calculations. The configurations of the adsorption of C<sub>2</sub>H<sub>4</sub>/Au<sub>38</sub>, O<sub>2</sub>/Au<sub>38</sub>, and O/Au<sub>38</sub> as well as the coadsorption of C<sub>2</sub>H<sub>4</sub>–O<sub>2</sub>/Au<sub>38</sub> were predicted. The calculation results show that C<sub>2</sub>H<sub>4</sub>, O<sub>2</sub>, 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 Au<sub>38</sub> 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 C<sub>2</sub>H<sub>4</sub> + O<sub>2</sub> + Au<sub>38</sub> → ethylene oxide + O/Au<sub>38</sub> is exothermic by 2.20–2.40 eV whereas those are 3.03–3.08 eV for the production of acetaldehyde and O/Au<sub>38</sub>. 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.