Structure Evolution and Associated Catalytic Properties of Pt- Sn Bimetallic Nanoparticles

Bimetallic nanoparticles (NPs) often show new catalytic properties that are different from those of the parent metals. Carefully exploring the structures of bimetallic NPs is a prerequisite for understanding the structure-associated properties. Herein, binary Pt- Sn NPs with tunable composition are prepared in a controllable manner. X-ray characterizations reveal that their structures evolve from SnO_2-x-patched PtSn alloys to SnO_2-x-patched Pt clusters when more tin is incorporated. An obvious composition-dependent catalytic performance is observed for the hydrogenation of α,β-unsaturated aldehydes: the selectivity to unsaturated alcohol increases substantially at high tin content, whereas the reaction rate follows a volcano shape. Furthermore, Pt sites are responsible for hydrogen dissociation, whereas oxygen vacancy (O_vac) sites, provided by SnO_2-x, drastically enhance the adsorption of carbonyl group.