Surface Modification on Pd Nanostructures for Selective Styrene Oxidation with Molecular Oxygen

The catalytic oxidation based on molecular oxygen (O-2) is one of the most preferable choices for oxidation reactions toward atom-efficient utilization of oxidants, in which heterogeneous catalysts based on palladium (Pd) nanostructures have been commonly used. However, in terms of selective styrene oxidation, it is still a great challenge to balance reactivity and selectivity by employing pure Pd catalysts. Herein, a well-designed model for seeking a selective oxidation catalyst based on surface lattice engineering is described. In the proposed model, Au atoms are sparsely deposited on the surface of concave Pd nanostructures. As such, the activation degree of adsorbed O-2 can be altered by simply tailoring the concentration of Au atoms on surface, suppressing the formation of over-oxidized byproducts. Moreover, the Pd@Au nanostructures reported here have sufficient plasmonic cross-sections for light harvesting, which enables light-driven catalysis through a photothermal effect. Taken together, the Pd@Au-0.08 concave nanostructures with an Au/Pd ratio of 8% achieve 87% main product selectivity with a conversion of 44% in the aerobic oxidation of styrene using molecular O-2 (1 atm) without additional initiator.