FePd nanowires modified with cyclodextrin as improved catalysts: effect of the alloy composition on colloidal stability and catalytic capacity

Abstract

In the present work, FePd nanowires of different compositions, namely Fe₈₅Pd₁₅, Fe₆₅Pd₃₅, Fe₅₅Pd₄₅ and Fe₀Pd₁₀₀, were synthesized by electrodeposition into the nanopores of alumina membranes. The samples were characterized by XRD, SEM, EDS, XPS, and magnetometry. The surface of the nanowires was functionalized with a cyclodextrin derivative (βCDMOD14) to obtain stable aqueous dispersions. A comprehensive study on the relationship between the alloy composition and the catalytic capacity of FePd nanowires (FePdNWs) modified with βCDMOD14 was conducted through the analysis of the rate constants (k_obs) of the reduction reaction of 4-nitrophenol to 4-aminophenol with sodium borohydride mediated by the FePdNWs in water. The highest value of k_obs was observed for Fe₅₅Pd₄₅ NWs, but the catalytic performance of Fe₆₅Pd₃₅ NWs was similar to the previous one, in spite of its lower Pd content. The presence of Fe atoms and the synthesis method promotes the formation of an fcc phase in the alloy, which shows higher catalytic activity than pure Pd, possibly because of a synergistic effect exerted by Fe. The catalysts can be easily recovered by taking advantage of their magnetic properties, to be reused after reactivation with βCDMOD14.