In situ X-ray Absorption Spectroscopic Studies of Magnetic Fe@FexOy/Pd Nanoparticle Catalysts for Hydrogenation Reactions

Core@shell Fe@FexOy nano particles ( have attracted a great deal of interest as potential magnetic supports for catalytic metals via galvanic exchange reactions. In this study Fe@Fe x O y /Pd bimetallic NPs were synthesized through galvanic exchange reaction s using 50:1, 20:1 and 5:1 molar ratio s of Fe@Fe x O y NPs to Pd(NO 3 2 . The resulting Fe@Fe x O y /Pd NPs have Pd nanoparticles on the Fe ox ide surfaces, and the NPs are linked in chains as shown by TEM analysis and EDX mapping. After galvanic reactions with Pd , the particles still retain their response to external magnetic fields . The magnetic properties of the resulting materials led to the ir successful application as nanometer sized magnetic stir bars for hydrogenation reactions. The Fe@Fe x O y /Pd NPs derived f rom the 5:1 molar ratio of their respective salts (Fe:Pd) exhibit ed a higher catalytic activity than particles synthesized from 20:1 and 50:1 molar ratios for the hydrogenation of 2 methyl 3 buten 2 ol . T he highest turnover frequency reach ed 3600 h 1 using ethanol as a solvent. In situ X ray absorption near edge structure (XANES) spectra show that the Fe@Fe x O y core shell particles in the Fe@Fe x O y /Pd system are easily oxidized when dispersed in water, while they are very stable if ethanol is used as a solvent. This oxidative stability has important implications for the use of such particles in real world applications.