How to Solve the Structure of Size Selective Nanoparticles

1. X18B How to Solve the Structure of Size Selective Nanoparticles B. Roldan Cuenya, J. R. Croy, S. Mostafa, F. Behafarid, L. Li, Z. Zhang, J. C. Yang, Q. Wang, A. I. Frenkel University of Central Florida, University of Pittsburgh, and Yeshiva University • The structure, size, and shape of γ-Al2O3-suported Pt nanoparticles (NPs) synthesized by inverse micelle encapsulation have been resolved via a synergistic combination of imaging and spectroscopic tools. • It is shown that this synthesis method leads to 3D NP shapes even for sub-nanometer clusters, in contrast to the raft-like structures obtained for the same systems via traditional deposition-precipitation methods. • Furthermore, a high degree of atomic ordering is observed for the micellar NPs in H2 atmosphere at all sizes studied, possibly due to H-induced surface reconstruction in these high surface area clusters. • Our findings demonstrate that the influence of NP/support interactions on NP structure can be diminished in favor of NP/adsorbate interactions when NP catalysts are prepared by micelle encapsulation methods. EXAFS data (in r-space) showing sensitivity to the size and shape of the nanoparticles prepared by inverse micelle encapsulation method. Polyhedral shapes of these particles (inset) were refined by combined, quantitative analysis of EXAFS and electron microscopy data. B. Roldan Cuenya, J. R. Croy, S. Mostafa, F. Behafarid, L. Li, Z. Zhang, J. C. Yang, Q. Wang, A. I. Frenkel Solving the structure of size-selected Pt nanocatalysts synthesized by inverse micelle encapsulation J. Am. Chem. Soc. 132, 8747-8756 (2010)). Work performed on beamlines X18B.