| AVS 58th Annual International Symposium and Exhibition | |
| Surface Science Division | Wednesday Sessions |
| Session SS2-WeM |
| Session: | Chemisorption on Metal & Oxide Nanoparticles |
| Presenter: | Li Liu, Texas A&M University |
| Authors: | L. Liu, Texas A&M University Y. Xu, Oak Ridge National Laboratory Z. Zhou, Texas A&M University Q. Guo, Chinese Academy of Sciences, China Z. Yan, Texas A&M University Y. Yao, Texas A&M University L. Semidey-Flecha, Oak Ridge National Laboratory D.W. Goodman, Texas A&M University |
| Correspondent: | Click to Email |
Single-layer graphene supported on transition metals provides a unique substrate for synthesizing metal nanostructures due to the high crystallographic quality, thermal stability, and chemical inertness of the graphene. Contrary to its formation of three-dimensional (3-D) nanoclusters on graphene supported on a SiO2 substrate, Au forms two-dimensional (2-D) islands on graphene moiré/Ru(0001). These Au islands maintain their 2-D structures up to 1 monolayer (ML) equivalent of Au dosage and are stable at room temperature. Our scanning tunneling microscopic study further shows that the 2-D Au islands are most likely two layers high, and conform to the graphene moiré in the lateral direction. Spin- and angle-resolved photoemission studies indicate even though these Au islands are largely electronically isolated, a weak through-graphene coupling exists between the Au islands and the Ru(0001) substrate. The structure for these 2-D Au islands and the corresponding electronic band structures are proposed based on DFT calculations.
Parallel studies using polarization modulation infrared reflection absorption spectroscopic (PM-IRAS) and high resolution electron energy loss spectroscopic (HREELS) indicate that CO adsorbs on these 2-D gold islands at 85 K with a characteristic CO stretching feature at 2095 cm-1 for a saturation coverage. Preliminary data obtained by dosing molecular oxygen onto this CO pre-covered surface suggest that the 2-D gold islands catalyze the oxidation of CO. These electron-rich, weakly coupled 2-D Au islands provide a unique platform to study the intrinsic catalytic activity of low-dimensional Au nanostructures.