CO adsorption on size-controlled Au nanoparticles grown on an h-BN/Rh(111) nanomesh surface has been examined to probe their potential catalytic properties. A combination of high-resolution electron energy loss spectroscopy (HREELS), temperature-programmed desorption (TPD), and density functional theory (DFT) calculations demonstrate that the CO adsorption strength depends heavily on the Au deposition coverage and particle morphology. Particles resulting from low Au coverages deposited at the liquid nitrogen temperature exhibit significantly enhanced CO binding relative to bulk crystalline Au. The resulting CO TPD spectra, and the significantly red-shifted C-O stretching frequency and negative charging of the Au nanoparticles as evidenced by HREELS and DFT, all correspond to those reported for catalytically active Au nanoparticles grown on reactive metal oxides, even though the h-BN/Rh(111) surface is free of carbon, oxygen, or defects. DFT modeling further suggests that the enhanced CO adsorption occurs at highly undercoordinated Au atoms on the perimeters of the nanoparticles. As the Au coverage is increased, the CO adsorption energy and C-O stretching frequency converge toward values associated with bulk Au. Annealing to 600 K results in bulk-like CO adsorption characteristics at any Au coverage. These results suggest that the h-BN/Rh(111) surface represents a potential platform for evaluating the role of Au vs support in low-temperature CO oxidation.
Publication Source (Journal or Book title)
Journal of Physical Chemistry C
McKee, W., Patterson, M., Huang, D., Frick, J., Kurtz, R., Sprunger, P., Liu, L., & Xu, Y. (2016). CO Adsorption on Au Nanoparticles Grown on Hexagonal Boron Nitride/Rh(111). Journal of Physical Chemistry C, 120 (20), 10909-10918. https://doi.org/10.1021/acs.jpcc.6b01645