Efficient and selective aerobic partial oxidation reactions via in situ-hydrogen peroxide generation electrocatalyzed by metal oxide-supported gold nanoparticles

• Metal oxide-supported Au nanoparticles (Au/MOs) catalyze 2e − -ORR. • Au/MOs exhibit catalytic activity for selective aerobic oxidation of alcohols. • Positive correlation exists between the activities and the MO conduction band edge. • In-situ H 2 O 2 generation mechanism was proposed for the aerobic alcohol oxidations. • This reaction mechanism has the potential to develop new organic synthesis processes. The partial aerobic oxidation of organic compounds is an ideal oxidation process in terms of the high oxygen utilization efficiency of O 2 and reduced environmental impact. However, the aerobic oxidation is usually spin-forbidden because the ground state O 2 is a triplet and the other reactants and products are singlet. Therefore, inactive O 2 must be activated, but under such conditions, complete oxidation of organic compounds tends to proceed. Meanwhile, H 2 O 2 is also very attractive as a clean and mild oxidant that is easier to activate than O 2 , but its high cost hinders its versatility. Active research on Au catalysts has revealed that Au nanoparticles (NPs) loaded on metal oxides (Au/MOs) show high catalytic activity and selectivity at low temperatures for various important chemical reactions, including aerobic alcohol oxidation. The catalytic activity is known to strongly depend on the type of MO support as well as the loading of Au and its particle size. In this Perspective, we discuss the reaction mechanism of Au/MO-catalyzed aerobic oxidation of alcohols to aldehydes, with a particular focus on the MO support effect on the catalytic activity. Firstly, electrochemical data and theoretical calculation results show that O 2 is reductively activated to produce H 2 O 2 on the Au/MO surface. Secondly, two-electron oxygen reduction reaction can also proceed chemically over the Au/MO catalysts, and the conduction band minimum level of the MO support is a good descriptor of the catalytic activity. Thirdly, based on these results and the key findings reported so far, an in situ - H 2 O 2 generation (HPG) mechanism is proposed for the Au/MO-catalyzed aerobic oxidation of alcohols. Finally, we summarize the conclusions and describe the future prospects for oxidative chemical transformations through in situ -HPG generation.