In this work, AgxPt100-x/C (x = 60, 80, 90 and 95) colloidal nanostructured electrocatalysts for the oxygen reduction reaction (ORR) were prepared by sequential reduction of AgNO3 and H2PtCl6 using an ultrasound-assisted colloidal method. The synthesized materials were characterized by UV/Vis spectroscopy, XRD, EDS and HRTEM. In addition electrochemical measurements were performed using cyclic voltammetry (CV) and thin-film rotating-disk electrode (TF-RDE) technique in 0.5 M H2SO4 at room temperature. Results of the physical characterization showed ring-like morphology of the nanostructured catalyst with a size distribution in the range of 6-16 nm. From steady polarization measurements, the AgxPt100-x/C nanocatalysts showed electrocatalytic activity towards the ORR like that obtained for Pt/C catalyst under the same experimental conditions and also favored the multielectron (n=4e-) charge transfer process to water formation (i.e., O2+4H++4e- → 2H2O).
nanoparticles, sonochemistry, electrochemical properties, ORR, PEMFC
This work was partially supported by the National Science and Technology Council of Mexico (CONACYT, project 83247). Special thanks are due to Professor Miguel J. Yacaman, from the International Center for Nanotechnology and Advanced Materials (ICNAM), at the University of Texas - San Antonio, U.S.A., for assistance with HRTEM observations and to Luzma Avilés-Arellano for her technical support.
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