| AVS 65th International Symposium & Exhibition | |
| Fundamental Discoveries in Heterogeneous Catalysis Focus Topic | Thursday Sessions |
| Session HC-ThP |
| Session: | Fundamental Discoveries in Heterogeneous Catalysis Focus Topic Poster Session |
| Presenter: | Amy Brandt, University of South Carolina |
| Authors: | A.J. Brandt, University of South Carolina T.D. Maddumapatabandi, University of South Carolina D. Shakya, University of South Carolina S. Farzandh, University of South Carolina D.A. Chen, University of South Carolina |
| Correspondent: | Click to Email |
Bimetallic Pt-Re clusters are systematically investigated on model supports in order to understand the effects of metal-metal interactions and metal-support interactions on cluster formation and catalytic activity for clean hydrogen production via the water-gas shift (WGS) reaction. Bimetallic catalysts have exhibited unique characteristics different from their single metal constituents, and interactions with the support are believed to have an influence on the chemistry taking place at the interface. Pure and bimetallic Pt-Re surfaces were prepared in ultrahigh vacuum (UHV) by vapor-deposition on model supports of TiO2(110), Pt(111), and highly oriented pyrolytic graphite (HOPG). WGS activity was studied in a UHV-coupled microreactor operating at a temperature of 160 °C and pressures of ~1 atm. On the TiO2 support, bimetallic clusters consisting of Pt at the surface and Re residing subsurface were found to have the highest activity for the WGS reaction, with turnover frequencies (TOF) nearly twice as high as monometallic Pt on TiO2. The TOF on the Pt single crystal was lower than Pt clusters supported by TiO2. A Pt-Re alloy with pure Pt at the surface and Re residing subsurface showed enhanced activity over pure Pt(111). Pt clusters deposited on TiO2 were investigated by scanning tunneling microscopy and found to have an increasing number of perimeter atoms compared to total atoms at decreasing Pt coverages. WGS experiments revealed a trend of increasing TOF for Pt coverages with increasing perimeter atom percentages, suggesting the Pt/TiO2 interfacial sites contribute to WGS activity. An alternative support of HOPG confirmed that Pt clusters on TiO2 have a greater TOF than Pt clusters on HOPG for the WGS reaction. In contrast to bimetallic Pt-Re clusters on TiO2, Pt-Re clusters on HOPG consisted of higher concentrations of Re at the surface, leading to lower TOFs for Pt-Re clusters on HOPG than the monometallic Pt on HOPG surface.