Anomalous Structural Disorder in Supported Pt Nanoparticles

作者：Vila Fernando D^*; Rehr John J; Nuzzo Ralph G; Frenkel Anatoly I

来源：Journal of Physical Chemistry Letters, 2017, 8(14): 3284-3288.

DOI：10.1021/acs.jpclett.7b01446

Supported Pt nanocatalysts generally exhibit anomalous behavior, including negative thermal expansion and large structural disorder. Finite temperature DFT/MD simulations reproduce these properties, showing that they are largely explained by a combination of thermal vibrations and low-frequency disorder. We show here that a full interpretation is more complex and that the DFT/MD mean-square relative displacements (MSRD) can be further separated into vibrational disorder, "dynamic structural disorder" (DSD), and long-time equilibrium fluctuations of the structure dubbed "anomalous structural disorder" (ASD). We find that the vibrational and DSD components behave normally, increasing linearly with temperature while the ASD decreases, reflecting the evolution of mean nanoparticle geometry. As a consequence the usual procedure of fitting the MSRD to normal vibrations plus temperature-independent static disorder results in unphysical bond strengths and Gruneisen parameters.

• 出版日期2017-7-20