Metal clusters have unique activity as their length scale decreases to the nanometer scale as the electronic structure is perturbed by the reduction in the number of metal-metal bonds. X-ray absorption spectroscopy is highly effective method for interrogating the electronic structure under reaction conditions. In this work, we examine the XANES of Pt nanoparticles for a variety of sizes over a variety of supports in combination with density functional theory calculations (DFT) to determine how size effects, adsorbate effects and alloy effects manifest themselve.  Our work helps to explain the competing effects of undercoodination and lattice contraction that occur in small metal nanoclusters. We found that that the shifts and changes in intensity in the edge may be explained in terms of molecular orbitals that may form between adsorbates and the metal surface during the bonding event. Finally we determined that hybridization dominates changes in the PDOS in d-band transition metal alloys.

Understanding XANES of supported Pt particles: Size, adsorbate and alloy effects

243rd National Meeting (2012)

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