Paper SS-TuA7
Nanocatalysis: New Developments in Catalytic Performance of Size- and Shape-Controlled Metal Nanoparticles

Tuesday, November 1, 2011, 4:00 pm, Room 109

Tailoring the chemical reactivity of nanomaterials at the atomic level is one of the most important challenges in catalysis research. In order to achieve this elusive goal, fundamental understanding of the geometric and electronic structure of these complex systems at the atomic level must be obtained. To study these effects, homogeneous size-and shape-selected Pt nanoparticles (NPs) were synthesized by means of diblock copolymer encapsulation.

The influence of the nanoparticle shape on the reactivity of Pt nanocatalysts supported on nanocrystalline γ-Al₂O₃ will be described. Nanoparticles with similar size distributions (~0.8-1 nm) but with different shapes were found to display distinct reactivities for the oxidation of 2-propanol. A correlation between the number of undercoordinated atoms at the nanoparticle surface and the onset temperature for 2-propanol oxidation was observed, demonstrating that catalytic properties can be controlled through shape-selective synthesis. Furthermore, the complex interaction between catalysts and reactants was investigated under operando conditions via X-ray absorption fine-structure spectroscopy. Platinum oxides were found to be the active species for the partial oxidation of 2-propanol (<140°C), while the complete oxidation (>140°C) was catalyzed by oxygen-covered metallic Pt NPs. Our findings highlight the decisive role of the nanoparticle structure and chemical state in oxidation catalytic reactions.