Palladium is an important catalyst for many industrial processes and chemical reactions. The conjunction of Pd and a metal oxide is of particular interest for improving catalytic performance in heterogeneous catalysis. Here we report the synthesis of Pd/Fe3O4 hybrid nanoparticles with controllable interface and the evaluation of their catalytic activities for CO oxidation. The synthesis involves a seed-mediated process in which Pd nanoparticles serve as seeds, followed by the deposition of the Fe3O4 layer in the solution phase. The adhesion of the oxide layer to the metal surface is through the reduced form of Fe. Upon thermal annealing, the Fe3O4 layer evolved from complete to partial coverage on the Pd core surface. This process is accompanied by increased crystallinity of Fe3O4. The resultant Pd–Fe3O4 nanoparticles with a partial Fe3O4 shell significantly lower the light-off temperature of CO oxidation.

A major goal in the field of ionic liquids is correlating transport property trends with the underlying liquid structure of the compounds, such as the degree of charge organization among the constituent ions. Traditional techniques for experimentally assessing charge organization are specialized and not readily available for routine measurements. This represents a significant roadblock in elucidating these correlations. We use a combination of transmission and polarized-ATR infrared spectroscopy to measure the degree of charge organization for ionic liquids. The technique is illustrated with a family of 1-alkyl-3-methylimidazolium trifluoromethansulfonate ionic liquids at 30°C. As expected, the amount of charge organization decreases as the alkyl side chain is lengthened, highlighting the important role of short-range repulsive interactions in defining quasilattice structure. Inherent limitations of the method are identified and discussed. The quantitative measurements of charge organization are then correlated with trends in the transport properties of the compounds to highlight the relationship between charge and momentum transport and the underlying liquid structure. Most research laboratories possess infrared spectrometers capable of conducting these measurements, thus, the proposed method may represent a costeffective solution for routinely measuring charge organization in ionic liquids.

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It has come to our attention that the equation describing the transverse optic-longitudinal optic (TO-LO) mode splitting is incorrectly written in our paper. The equation for TO-LO splitting was first derived by Decius 1 and was written in terms of angular frequency, ω, with units of rad s −1 . In later papers, however, Decius and co-workers 2−5 favored the symbol ν in lieu of ω for the vibrational frequency (see especially refs 4 and 5). Unfortunately, we did not realize the author's notation change from ω to ν was not accompanied by a change in units from rad s −1 to s −1 . Therefore, our eq 1 should be written Addition/Correction pubs.acs.org/JPCB