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Controlling the stoichiometry of supported bimetallic nanoparticles is essential in many catalytic reactions, notably selective CO 2 hydrogenation. Thus, a new strategy to ensure the preferred stoichiometry (1:1) of supported bimetallic PdZn nanoparticles is presented, involving the deposition of a heterobimetallic precursor, [PdZn(μ-OOCMe) 4 ] 2 on a CeZrO x support. After calcination and reduction, the material contained mainly a PdZn alloy, as revealed by powder XRD and XAFS, and further supported by XPS, TEM-EDX, elemental analysis and in-situ IR at low temperature using CO as probe molecule. Moreover, a minor phase of oxidized Zn was determined by XAFS. This PdZn/CeZrOx reduced catalyst was combined with SAPO-34 to form a tandem catalytic system for CO 2 conversion to hydrocarbons. This system could readily convert CO 2 and H 2 at high temperature (380 °C) into hydrocarbons with a conversion of 24% and high relative selectivity in light hydrocarbons (C2–C3: 82%) with virtually no deactivation of the catalyst after 16 h on stream. Controlled experiments were performed with Pd/CeZrOx and Zn/CeZrOx in order to gain supplementary insights on this system: Pd/CeZrOx gave only methane and Zn/CeZrOx gave mainly CO under the same conditions. The latter clearly shows that the control of the formation of PdZn phase has great impact for the selective production of hydrocarbons. [Display omitted] • Development of PdZn supported on CeO 2 , ZrO 2 and CeZrOx for the conversion of CO 2 to methanol. • Catalyst PdZn/CeZrOx presents highly dispersed bimetallic PdZn nanoparticles with 1:1 ratio. • CO 2 conversion to light hydrocarbons is studied over tandem catalysts comprising PdZn supported on oxide and SAPO-34. • PdZn/CeZrOx/SAPO-34 catalysts present high CO 2 conversion and selectivity in light hydrocabons. [ABSTRACT FROM AUTHOR]

Abstract: We report on the fabrication of completely uniform monolayer graphene on a metal thin film over a 150mm Si substrate at a low temperature of 600°C by inductively coupled plasma-enhanced chemical vapor deposition (ICPCVD). Through novel use of bimetallic catalyst such as CuNi and AuNi alloys we were able to control catalytic reaction at the metal surface and grow complete monolayer graphene with a Ni content less than 20at.%. We also found that the 2D/G intensity ratio in the Raman spectra was almost invariant with growth time and the C 1s peak in the XPS spectra was observed only at the metal surface. This implies that monolayer graphene was possibly grown on these Ni-doped copper and gold catalysts by a self-limiting surface reaction under our CVD condition. From DFT calculations, it was shown that the catalytic activity of normally inactive Cu and Au could be enhanced through the addition of Ni atoms at surface sites, providing graphene growth at lower temperatures than pure Cu or Au. The carrier mobility of graphene films grown on these CuNi and AuNi alloy catalyst was measured to be over 9000cm2 V−1 s−1 at room temperature, which is comparable to that of CVD graphene film grown on Cu foil. Therefore, we suggest an efficient way in growing a complete monolayer graphene on thin films at low temperatures, which could be a key issue in the application of graphene devices. [Copyright &y& Elsevier]