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The thermal chemistry of 2-propanol and 2-propyl iodide on clean and oxygen-pretreated Ni(100) single-crystal surfaces was studied by temperature programmed desorption (TPD), X-ray photoelectron spectroscopy (XPS), and reflection−absorption infrared spectroscopy (RAIRS). 2-Propyl iodide was used as a precursor for the preparation of 2-propyl surface species, in analogy to chemistry reported for other halo hydrocarbons. Those 2-propyl groups were shown to convert to acetone on both oxygen- and hydroxide-covered Ni(100) surfaces by following a two step mechanism, starting with a facile oxygen insertion into the metal−alkyl bond. The resulting 2-propoxide surface moiety, an intermediate that can also be prepared via dehydrogenation of the hydroxyl group in adsorbed 2-propanol, is stable up to about 300 K, at which point it undergoes β-hydride elimination to acetone. Coadsorbed surface hydroxide facilitates the first oxygen insertion reaction, and surface oxygen enhances the latter conversion of 2-propoxide to acetone. Some alcohol dehydration to propene is also observed, presumably by reaction of two hydrogen-bonded alcohol molecules. These results point to the feasibility of designing nickel-based catalysts for the selective partial oxidation of hydrocarbons.

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Direct X-ray photoelectron (XPS) and reflection−absorption infrared (RAIRS) spectroscopic evidence is reported here for the formation of a C−O bond via the thermal activation of adsorbed 2-propyl groups in the presence of chemisorbed oxygen on a Ni(100) single-crystal surface. The resulting species, a 2-propoxide intermediate, was identified by a shift in binding energy of some of the C 1s photoelectrons to approximately 285.3 eV and by the appearance of a C−O stretching vibrational mode in the infrared spectrum at about 1095 cm-1. The propoxide species forms around 200 K and remains on the surface until temperatures above 300 K, at which point they undergo β-hydride elimination to yield acetone.

Structural studies have been carried out on Ag 2 V 4 O 11 ͑silver vanadium oxide, SVO͒ and Li x Ag 2 V 4 O 11 , lithiated SVO with x = 0.72, 2.13, and 5.59 using nuclear magnetic resonance ͑NMR͒ and X-ray absorption spectroscopy ͑XAS͒. Lithium-7 NMR indicates the formation of a solid electrolyte interphase layer on the x = 0.72 sample and lithium intercalation into both octahedral and tetrahedral sites in the SVO lattice, and that most but not all of the Ag ͑I͒ is reduced prior to initiation of V͑V͒ reduction. Vanadium-51 NMR studies of SVO and lithiated SVO show decreased crystallinity with increased lithiation, as previously reported. Silver XAS studies indicate the formation of metallic silver crystallites in all the lithiated samples. A comparison of X-ray absorption near edge spectroscopy spectra for vanadium in these samples with those of reference compounds shows that some reduction of vanadium ͑V͒ occurs in the lithiated SVO with x = 0.72 and increases with further lithiation leading to the formation of V͑IV͒ and V͑III͒ species. The results of this study indicate that vanadium͑V͒ reduction occurs in parallel with silver ͑I͒ reduction during the initial stages of SVO lithiation, leading ultimately to the formation of vanadium ͑IV͒ and ͑III͒ species with further lithiation.The lithium/silver vanadium oxide ͑SVO͒ primary cell is employed for a number of biomedical applications but its principal use is as a power source in implantable cardiac defibrillators ͑ICDs͒ which are required to produce 25-40 Joule pulses to paralyze the heart during fibrillation events, following which the normal heart beating rhythm resumes. This function requires a cell capable of producing 1-4 A pulses to charge a capacitor in addition to providing the background current of 10-30 A for pacing and sensing functions. Silver vanadium oxide ͓Ag 2 V 4 O 11 ͔, which belongs to the class of vanadium bronzes and possesses semiconducting properties, has been successfully used as the cathode in this system due to the inherent high rate capability of this material.Electrochemical reduction of SVO is a multistep process which occurs between 3.2 and 2.0 V with the following overall reaction: Ag 2 V 4 O 11 + 7Li = Li 7 Ag 2 V 4 O 11 . SVO has a theoretical capacity of 315 mAh/g to a 2.0 V background voltage cutoff. Extensive electrochemical characterization of the Li/SVO system has been carried out by several other groups. 1-3 Mechanistic studies of this multistep reduction have also been conducted and have identified the formation of silver metal in the early stage of the reaction, through the use of X-ray powder diffraction and scanning electron microscopy/ energy-dispersive spectroscopy ͑SEM/EDS͒. 4,5 However, electrochemical and X-ray diffraction measurements yield only average structural changes related to lithium insertion. The primary motivation of this work was to apply spectroscopic methods that reveal atomic level information about the environments of all three metal ions in lithiated SVO; lithium, through 7 Li nuclear magnetic resonan...