Self-supported bimetallic nanoporous networks (BNNs) function as a unique model system for direct analysis of the reactivity of bimetallic catalysts without any masking support or surfactant effects. Here we show a simple and highly versatile approach for synthesis of BNNs and demonstrate the influence of preparation conditions on the BNN structure, composition and catalytic reactivity. Pt-Re BNN was prepared by reduction of double complex [Pt(NH3)4][Re(Cl6)] salt crystals, in which two oppositely-charged metal complexes are evenly distributed in each unit cell in a 1:1 ratio. Exposure of the salt crystals to reducing conditions induced the evaporation of the inorganic ligands, collapse of the salt structure and reduction of the metal ions for the formation of high surface area Pt-Re BNNs. Single-particle X-ray fluorescence tomography and in-situ X-ray absorption spectroscopy measurements identified that the bulk and surface composition of the bimetallic structure and the oxidation state of the two metals can be tuned by adjusting the reduction conditions of the bimetallic salt. Pt-Re BNN showed reactivity in deoxydehydration reaction of glycerol toward the selective formation of allyl alcohol. Combination of reactivity and spectroscopic measurements revealed that enhanced reactivity was correlated to the presence of highly oxidized Re species (mostly Re+7) and equal distribution of Pt and Re on the BNN surface.

Pt-Re nanoporous networks: A well-defined model system for elucidating composition-reactivity correlations in bimetallic catalysts

2019 Spring National Meeting

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