title: Metallic nature and surface diffusion of CO adsorbed on Ru nanoparticles in aqueous media: A 13C NMR study.
abstract: We report the first observation of the 13C nuclear magnetic resonance spectroscopy (NMR) of 13CO, adsorbed from 13CO saturated 0.5 M sulfuric acid solutions, onto the surfaces of commercial Ru-black nanoparticles. The 13C NMR spectra consist of a symmetrically broadened peak having a large isotropic shift as compared to CO adsorbed onto supported Ru catalysts. The variation of the spin-lattice relaxation rate follows Korringa behavior, indicating the metallic nature of adsorbed CO, in addition to varying across the spectrum in a Korringa-like manner. Motional narrowing of the NMR spectrum at higher temperatures, together with an additional contribution to the spin-lattice relaxation rate, indicate that adsorbed CO undergoes rapid diffusion on the particle surfaces. A two-band model analysis of the NMR results indicates that the CO adsorption bond is weaker on Ru as compared to either Pt or Pd. This is also supported by a reduction in the activation energy for CO diffusion on Ru vs either Pt or Pd nanoparticles.
authors.forename: Panakkattu K
authors.initials: PK
authors.lastname: Babu
authors.forename: Jong Ho
authors.initials: JH
authors.lastname: Chung
authors.forename: Seung Taek
authors.initials: ST
authors.lastname: Kuk
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kobayashi
authors.forename: Eric
authors.initials: E
authors.lastname: Oldfield
authors.forename: Andrzej
authors.initials: A
authors.lastname: Wieckowski
mesh_terms: D000327:Adsorption; D002247:Carbon Isotopes / Q000737:chemistry*; D002384:Catalysis; D009682:Magnetic Resonance Spectroscopy / Q000379:methods*; D053768:Metal Nanoparticles / Q000737:chemistry*; D008670:Metals / Q000737:chemistry*; D046529:Microscopy, Electron, Transmission; D008956:Models, Chemical; D010165:Palladium / Q000737:chemistry; D010984:Platinum / Q000737:chemistry; D012413:Rubidium / Q000737:chemistry*; D013696:Temperature; D014867:Water / Q000737:chemistry
chemical_list: D002247:Carbon Isotopes; D008670:Metals; D014867:Water; D010984:Platinum; D010165:Palladium; D012413:Rubidium