| AVS 62nd International Symposium & Exhibition | |
| Nanometer-scale Science and Technology | Wednesday Sessions |
| Session NS+EN+MG+SS+TF-WeA |
| Session: | Nanoscale Catalysis and Surface Chemistry |
| Presenter: | Sampyo Hong, University of Central Florida |
| Authors: | S. Hong, University of Central Florida G. Shafai, University of Central Florida T.S. Rahman, University of Central Florida |
| Correspondent: | Click to Email |
We have studied the effects of γ-Al2O3(110) support on the geometry and electronic structures of H-coveredPtx (x=22,44) nanoparticles (NP) using density functional theory (DFT). We find that the unoccupied d-band center of γ-Al2O3(110) supported Pt NPs exhibits a blue shift with decreasing Pt size similarly as the measured XANES absorption peak energy of Pt NP samples. In fact, our DFT results reveal that the shift of the unoccupied d-band center of Pt NPs is dependent of surface hydroxylation level on γ-Al2O3(110). At higher hydroxylation the calculated unoccupied d-band center can even show red shift. Thus, consideration of hydroxylation level on γ-Al2O3(110) is needed to properly interpret support effect from XANES spectra. Overall, the strength of Pt- γ-Al2O3(110) binding seems to be a reasonable measure of the shift of unoccupied d-band center as a result of metal-support interaction: the stronger the interaction the more the blue shift. In the light of these results, it is plausible to postulate that the adsorption energy shift of XANES spectra represent the strength of metal-support interaction (support effect). A remarkable example of such hydroxylation tuned metal-support interaction is structural transition of Pt22 from a biplanar to a 3D-like geometry as a function of support hydroxylation.
This work is supported in part by DOE Grant DE-FG02-07ER15842.