Investigation of Au/Co 3 O 4 nanocomposites in glycol oxidation by tailoring Co 3 O 4 morphology.

The interfacial perimeter of nanogold and supports is often deemed as the catalytically active site for multiple reactions while the geometrical configuration of the interfacial perimeter at atomic scale is less studied. Herein, gold nanoparticles (NPs) of ca. 2.0 nm are dispersed on Co 3 O 4 support in the shape of nanocubes (dominant Co 3 O 4 (001) facet) and nanoplates (Co 3 O 4 (111)), which forms different Au-Co 3 O 4 interfaces with respect to the specific facet of the oxide support. A comparison is made on the basis of the interfacial structures and catalytic behavior of ethylene glycol oxidation. STEM analysis identifies that these metallic Au NPs interact with Co 3 O 4 with an orientation relationship of Au/Co 3 O 4 (001) and Au/Co 3 O 4 (111). XPS and Raman spectroscopy investigations reveal the important variations in the reactivity of surface oxygen, surface O ads /O L ratio, and evolution of surface oxygen vacancies upon variation of the Co 3 O 4 shape. Au/Co 3 O 4 -P exhibits much better catalytic activity than the Au/Co 3 O 4 -C counterpart in the aerobic oxidation of ethylene glycol, which is promoted by surface oxygen vacancies and intrinsic defects. It has been revealed that the surface oxygen vacancies participate in activating O 2 , thus making Co 3 O 4 -P a superior support for Au NPs in the catalysis of ethylene glycol oxidation.