The electrochemical codeposition method has been used to prepare a series of Pt/MoO x /glassy carbon ͑GC͒ electrodes with different atomic ratios of Pt to Mo. The advantage of this method is the mixing of metal and support on a microscopic level ͑atomic or molecular scale͒. That is, to disperse the Pt microparticles into the molybdenum oxide on a GC substrate. The Pt/MoO x /GC electrode was prepared by scanning the electrode potential between 0.55 and Ϫ0.70 V vs. Hg͉Hg 2 SO 4 in potassium hexachloroplatinate, sodium molybdate, and 2.2 M sulfuric acid solution at a GC substrate using a scan rate of 20 mV/s. The scanning electron microscopy results show that the Pt and MoO x microparticles are uniformly dispersed on the GC electrode surfaces. In addition, the modified electrode exhibits electrocatalytic activity for the oxidation of methanol. Based on the catalytic properties, the optimal concentrations for the preparation of the composite electrode is 3.0 mM in K 2 PtCl 6 and 300 mM of Na 2 MoO 4 . X-ray photoelectron spectroscopy ͑XPS͒ analyses indicate that the best Pt to Mo atomic ratio is in the range between 1.5 and 2.0. In addition, the XPS spectra present a broad peak in the Mo ͑3d͒ binding energy region revealing the existence of Mo 6ϩ species as well as lower valence state Mo 5ϩ and Mo 4ϩ . Finally, a reaction mechanism is suggested for methanol oxidation at this composite Pt/MoO x GC electrode.Numerous research studies have been conducted on the development of a catalyst for the anode in direct methanol-air fuel cells ͑DMFCs͒ in the last ten years. As an example, we could mention PPy/Pt, 1 Pt/Ru/Os/Ir, 2 Pt/Ru/Os, 3 Pt/Re, 4 Pt/Ru, 5-12 Pt/Sn, 13-15 and Pt/Mo 16-18 composite systems. Nevertheless, the step toward the practical application has not been developed as fast as had been expected. Mainly, the poisoning of the anode catalysts hinders DMFC performance by the adsorbed carbonyl species derived from methanol oxidation. [19][20][21][22][23][24][25] Dispersed noble metal catalysts supported on high surface area inorganic oxides are of considerable interest for catalysis. 26,27 The support is used to separate the catalytic particles physically and decrease their agglomeration rate. The oxide support is believed to modify the electronic nature of the metal particles as well. Thus, affecting their chemisorptive and catalytic properties. The enhancement of surface catalytic activity by the metal-support interaction, as well as the large surface area achieved with the low loading levels, makes such systems attractive for the application in DMFCs. The requirement of these catalytic systems is that the intimate contact between metal and support should be as great as possible.Rolison and co-workers 10-12 have reported a thermogravimetric and X-ray photoelectron spectroscopy ͑XPS͒ analysis of as-received Pt-Ru electrocatalysts. These results indicate that DMFC materials contain substantial amount of hydrous ruthenium oxide (RuO x H y ). A potential misidentification of nanoscale Pt-Ru blacks arises because RuO...

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Representative organoborane mixtures were quantitatively converted to their borohydrides through their reaction with activated KH (KH), permitting their detailed analysis by (11)B NMR. Through the treatment of commercial KH with a THF solution of lithium aluminum hydride (LAH), a dramatic change in the surface morphology results as revealed by scanning electron microscopy (SEM). Energy dispersed spectroscopy (EDS) was employed to reveal that the LAH treatment deposits a significant amount of an unknown aluminum-containing species on the surface of the KH, which imparts a unique reactivity to the KH. Even highly hindered organoboranes are quantitatively converted to their borohydrides by replacing electronegative groups (e.g., OR, halogen) with hydrogen, retaining only the carbon ligation. Through this simple KH treatment, complex organoborane reaction mixtures are converted to the corresponding borohydrides whose (11)B NMR spectra normally exhibit resolved signals for the individual species present. The integration of these signals provides quantitative information on the relative amounts of each component of the mixture. New generalities for the effect of alpha-, beta-, and gamma-substituents have also been determined that provide a new, simple technique for the determination of the isomeric distribution in organoborane mixtures resulting from common organoborane processes (e.g., hydroboration). Moreover, the (1)H-coupled (11)B NMR spectra of these mixtures reveal the extent of alkylation for each species present. Representative organoboranes were examined by this new technique permitting a simple and convenient quantitative analysis of the regio- and diastereomeric composition of a variety of asymmetric organoborane processes. Previously unknown details of pinene-based hydroborations and reductions are revealed for the first time employing the KH (11)B NMR technique.

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