Oxygen reduction electrocatalyst of Pt on Au nanoparticles through spontaneous deposition.

A straightforward one-step spontaneous deposition approach for growth of Pt atomic shell on Au nanoparticles and the superior activity and durability of the resulted Pt-on-Au nanoparticles for the oxygen reduction reaction (ORR) are reported. Transmission electron microscopy, X-ray photoelectron spectroscopy, energy-dispersive spectrometry, and electrochemical measurements indicate that Pt can be spontaneously deposited on Au surface upon simply dispersing carbon-supported Au nanoparticles in PtCl42–-containing solution, without introducing any extraneous reducing agents or any pre/post-treatments. The deposited Pt atoms are uniformly distributed on the surface of Au nanoparticles, with coverage tunable by the concentration of PtCl42– and temperatures. An approximate monolayer of Pt forms at temperature of ca. 80 °C and PtCl42– concentrations of above 10–4 mol/L. The obtained Pt-on-Au core–shell nanoparticles catalyze the ORR with specific and mass activities of Pt that are 3.5 times higher than that of pure Pt nanoparticles. Moreover, they exhibit no visible activity degradation after undergoing long-term oxidization/reduction cycling in O2-saturated acid media, therefore showing great prospect as durable cathode electrocatalysts in proton-exchange membrane fuel cells.