O2 Adsorption and Oxidative Activity on Gold-Based Catalysts with and without a Ceria Support

Understanding the O-2 adsorption and oxidative activity on gold-based catalysts is of great significance for gold catalysis. According to the adsorption behaviors of O-2 on Au(111)(+), 3Au/Au(111)(+), Au-19(+), and Au-9/CeO2(111), the electronic, nature of why O-2 weakly interacts with free positively charged Au substrate while it strongly interacts with Au cluster supported on ceria is well-explained herein. The ceria support serves as an electronic repository, where it gains and stores electrons from the supported metal cluster and releases them when the metal cluster interacts with molecular O-2. The possible oxygen species on gold-based catalysts have been systematically confirmed for the first time. On the Au-9/CeO2 modeling catalyst, a peroxide species forms when O-2 locates at the hollow site of Au-9, while a superoxide forms for O-2 at the top site of a Ce atom. It is very interesting to find that Ce3+ ion distributions in Au /CeO2 catalysts have diverse possibilities. The superoxide close to Au-9 has the highest oxidative activity. The interface between the Au cluster and ceria surface is the active site for Au /CeO2 catalysts. The present work sheds light on understanding the oxidative mechanism of metal/support catalysts, as well as the development of new catalysts with high performance at relatively low temperature.