Carbon-supported pseudo-core-shell Pd-Pt nanoparticles for ORR with and without methanol

Carbon-supported Pd-rich pseudo-core-shell Pd-Pt (Pd@Pt/C) nanoparticles, with Pt coverage close to a monolayer, were prepared from a simple galvanic replacement reaction between Pd/C particles and PtCl(4)(2-) at 100 degrees C. The pseudo-core-shell architecture was confirmed by extensive microstructural characterization techniques. The binding energy shifts in the Pt 4f X-ray photoelectron spectra, in particular, suggest an electron exchange between Pd and Pt, and possible strain effects in Pt caused by the underlying Pd core. The activity of the pseudo-core-shell nanoparticles in the oxygen reduction reaction (ORR) was studied in acidic solutions with and without methanol. The electrocatalysts prepared as such were active for ORR at room temperature, even in the presence of 0.1 M methanol. The pseudo-core-shell Pd(70)@Pt(30) catalyst, in particular, compared rather favorably with a Pt/C catalyst with twice the Pt mass loading in terms of the ORR activity, cost, and methanol tolerance. (c) 2008 The Electrochemical Society.