Effects of hydroxylated $\gamma $-Al$_{2}$O$_{3}$ support and H adsorbate on the Geometry and Electronic Structure of Pt Nanoparticles

We have studied the effects of hydroxylated $\gamma $-Al$_{2}$O$_{3}$(110) support and H adsorbate on the geometry and electronic structures of Pt$_{x}$ (n$=$22,44) nanoparticles (NP) using DFT. We find that Pt$_{22}$ interacts more strongly with a less hydrated support, while Pt$_{44}$ more with a hydroxylated one. We also find a structural transition of the Pt$_{22}$ (and not Pt$_{44})$ from a biplanar to a 3D-like shape as a function of hydroxilation. H induces a much larger shift in the unoccupied d-band center than does the support. Also, these shifts are well correlated with metal-support interaction. The increased hydroxylation on $\gamma $-Al$_{2}$O$_{3}$(110) causes weaker metal-support interaction. As a result, the d-band width of a Pt NP decreases causing the center of the unoccupied d band to shift to lower energy (red shift). In the light of these results, we will discuss the features of XANES spectra obtained for $\gamma $-Al$_{2}$O$_{3}$(110) supported Pt nanoparticles [1]. \\[4pt] [1] Behafarid et al, Phys. Chem. Chem. Phys. 14, 11766 (2012).