The preparation of bimetallic nanoporous networks (BNNs) that combine the high surface area and thermal stability of inorganic nanostructures with the unique catalytic properties of bimetallic systems is highly desirable. Here we show a simple and highly versatile approach for synthesis of Pt-Re BNN 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 various ensemble-based spectroscopy measurements (X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy) identified that the bulk and surface compositions of the bimetallic structure and the oxidation state of the two metals can be tuned by adjusting the reduction temperature 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 Re7+) and equal distribution of Pt and Re on the BNN surface.
Bibliographical noteFunding Information:
X-ray tomography measurements were carried out on beamline P06 at Petra III at DESY, a member of the Helmholtz Association (HGF). X-ray absorption experiments were performed at CLAESS beamline at ALBA Synchrotron. S.D. acknowledges the Israeli Ministry of Energy and the Rudin fellowship for their financial support. Avishai Barnoy is acknowledged for his assistance in analysis of the X-ray tomography images.
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