Insights into oxygen activation on metal clusters for catalyst design

Abstract

The activation mechanism of O₂ molecules plays a vital role in the development of catalysts for aerobic oxidation reactions. To gain insights into the activation mechanism of O₂, square fragments of metal clusters are designed as the most promising active sites for the activation of O₂ in aerobic oxidation reactions, where both the adsorption energy of O₂ (E_ad-O2) and the O–O bond energy (E_O–O) in the adsorbed O₂ are simultaneously small. A new descriptor E_sum, combining E_ad-O2 and E_O–O, is proposed for evaluating the catalytic activity of aerobic oxidation reactions. The above insights are verified in the Ag₃₈ cluster for CO oxidation by density functional theory calculations. The energy barrier for CO oxidation on the square Ag₄ fragment is found to be 0.30 eV, which indicates that CO oxidation could occur at room (even lower) temperature.