X-ray photoelectron and m?ssbauer spectroscopy studies of bimetallic ~(57)Fe-Pd nanocomposites prepared by metal-vapor synthesis

摘要

X-ray photoelectron and M?ssbauer spectroscopy were used to study the composition and structure of ~(57)Fe-Pd bimetallic black and ~(57)Fe-Pd/SiO_2 nanocomposites prepared by metal-vapor synthesis. The main parameters of the core level photoelectron spectra of ~(57)Fe-Pd systems were determined. The bimetallic system was shown to be a disordered amorphous structure consisting of Pd particles, superparamagnetic γ-Fe_2O_3 nanoparticles with size 8-10 nm, and a Fe-O-Pd solid solution. Considerable broadening of Pd 3d peaks in ~(57)Fe-Pd/SiO_2 and an increase in the O1s-Si 2p energy interval by 0.4 eV with respect to the spectrum of initial SiO2 were observed; this was evidence of the interaction of Pd with the support. The binding energy of Fe 2p_(3/2) peak in the nanocomposite spectrum was close to that of Fe_2O_3, but had a smaller width of the satellite peak and a larger spin-orbit splitting, which was indicative of a considerable amount of FeOOH on the surface compared with the other iron oxides.