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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 ...

The effect of growth conditions on the structural and electronic properties of the polar/non-polar LaCrO$_3$/SrTiO$_3$ (LCO/STO) interface has been investigated. The interface is either insulating or metallic depending on growth conditions. A high sheet carrier concentration of 2x10$^{16}$ cm$^{-2}$ and mobility of 30,000 cm$^2$/V s is reported for the metallic interfaces, which is similar to the quasi-two dimensional gas at the LaAlO$_{3}$/SrTiO$_{3}$ interface with similar growth conditions. High-resolution synchrotron X-ray-based structural determination of the atomic-scale structures of both metallic and insulating LCO/STO interfaces show chemical intermixing and an interfacial lattice expansion. Angle resolved photoemission spectroscopy of 2 and 4 uc metallic LCO/STO shows no intensity near the Fermi level indicating that the conducting region is occurring deep enough in the substrate to be inaccessible to photoemission spectroscopy. Post-growth annealing in flowing oxygen causes a reduction in the sheet carrier concentration and mobility for the metallic interface while annealing the insulating interface at high temperatures and low oxygen partial pressures results in metallicity. These results highlight the critical role of defects related to oxygen vacancies on the creation of mobile charge carriers at the LCO/STO heterointerface.