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PdAg electrocatalyst was prepared following two different methods, i.e. borohydride reduction of metallic ions and sonochemistry. X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations indicate the formation of crystalline PdAg particles with an average particle size of 10 nm from chemical reduction, and 12 nm from sonochemistry. The electrocatalytic activity of PdAg, for the oxygen reduction reaction (ORR) was characterized using cyclic voltammetry (CV), rotating disk electrode (RDE) and electrochemical impedance spectroscopy (EIS), in 0.5M H2SO4. Mass-transfered-corrected Tafel plots show an enhancement of the electrocatalytic activity associated to the incorporation of silver to palladium. EIS diagrams of PdAg electrocatalyst present one or two time constants depending on the electrode potential, E. The E at which appears the second time constant depends on the method of catalyst preparation. The difference in E was attributed to the different crystalline percentage due to the catalyst preparation method.
PdAg Electrocatalyst; Oxygen Reduction Reaction; Impedance Spectroscopy.
This research project was partially supported by a Grant of National Science and Technology Council of Mexico, CONACYT (Ref. 83247) and by the Mexico City Science and Technology Institute, ICYTDF (OSF). DCMC thanks to CONACYT for doctoral fellowship. GVH thanks the financial support from CONACYT through a postdoctoral grant. The authors acknowledge to Juan Antonio Jimenez, Carlos Flores and Dr. José Chavez for the technical assistance in XRD and TEM measurements.
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