title: A comparative in situ 195Pt electrochemical-NMR investigation of PtRu nanoparticles supported on diverse carbon nanomaterials.
abstract: This paper reports a detailed in situ 195Pt electrochemical-nuclear magnetic resonance (EC-NMR) study of PtRu nanoparticles (NPs) that had a nominal atomic ratio of Pt : Ru = 1 : 1 and were supported on carbon nanocoils and carbon black (Vulcan XC-72) respectively. The particle sizes of the two samples were determined by X-ray diffraction using the Sherrer equation: 3.6 nm for the former and 3.2 nm for the latter, which were further corroborated by transmission electron microscope measurements. By taking advantage of a unique correlation between the spectral frequency of the 195Pt NMR resonance and the radial atomic position in a particle, qualitatively- and spatially-resolved local Pt atomic fractions in the particles were deduced by using a Ruderman-Kittel-Kasuya-Yosida (RKKY) J-coupling-based method as a function of different electrode potentials. The results indicated that both samples had Pt-enriched cores and Pt-deprived surfaces and, most importantly, the local Pt concentration varied as the electrochemical environment changed. The spatially-resolved Fermi level local densities of states (E(f)-LDOS), which are a measure of the electronic frontier orbitals in metals, were deduced across the NMR spectrum and correlated with the EC activity in methanol electro-oxidation. The results were also compared to those obtained previously from Pt/Ru NPs supported respectively on carbon and graphite nanofibers.
authors.affiliation: Department of Chemistry, Georgetown University, 37th & O Streets, NW, Washington DC 20057, USA.
authors.forename: Fatang
authors.initials: F
authors.lastname: Tan
authors.forename: Bingchen
authors.initials: B
authors.lastname: Du
authors.forename: Aaron L
authors.initials: AL
authors.lastname: Danberry
authors.forename: In-Su
authors.initials: IS
authors.lastname: Park
authors.forename: Yung-Eun
authors.initials: YE
authors.lastname: Sung
authors.forename: YuYe
authors.initials: Y
authors.lastname: Tong
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D003102:Colloids / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D004579:Electron Transport; D009682:Magnetic Resonance Spectroscopy; D008956:Models, Chemical; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D010084:Oxidation-Reduction; D010984:Platinum / Q000737:chemistry*; D012413:Rubidium / Q000737:chemistry*; D013499:Surface Properties
chemical_list: D003102:Colloids; D010984:Platinum; D002244:Carbon; D012413:Rubidium