Effects of coordination number of Au catalyst on oxygen species and their catalytic roles

To explore the effects of coordination number of Au nanoparticles on oxygen species and their catalytic roles is very important in gold catalysis. Based on the systematic study of oxygen adsorption on Au(997) by density functional theory calculation, the quantitative correlation for different oxygen species with coverage and Au coordination number is established in theory. The only O adatoms near step area with relatively low Au coordination numbers exist at low coverage (<1/18 ML), O adatoms adsorb at terrace areas with relatively high Au coordination numbers at medium coverage (1/18-2/9 ML); while oxygen islands form at high coverage (>2/9 ML). The theoretical predictions are in good agreement with the experimental observations in TDS spectrum. On the basis of Langmuir-Hinschelwood and Eley-Rideal mechanisms for NO oxidation, the activities of the three different oxygen species also exhibit correlation with Au coordination number. The oxygen island shows the highest oxidation activity, followed by the O adatom at terrace surface; while the O adatom near step area has the lowest oxidative performance. This work will shed light into the understanding of gold catalysis. (C) 2016 Elsevier B.V. All rights reserved.