Porous Pd layer-coated au nanoparticles supported on carbon: Synthesis and electrocatalytic activity for oxygen reduction in acid media

This paper reports the simple synthesis and characterization of carbon-supported Pd layer-coated Au nanoparticles (AuPd/C). A series of AuPd/C with various Pd/Au weight percentage ratios were prepared by the spontaneous deposition of a Pd shell on a Au nanoparticle core using different Pd precursor concentrations (0.5, 5, 10, 20 mM PdCl₂). Au nanospheres encapsulated by the porous Pd shells are confirmed by transmission electron microscopy (TEM), UV-vis absorption spectroscopy, and scanning TEM. The catalytic activity of the AuPd/C for the oxygen reduction reaction (ORR) was investigated by rotating disk electrode voltammetry in 0.5 M H₂SO₄. In particular, a AuPd/C with a Pd/Au ratio of 0.61 shows superior ORR activity along with satisfactory stability and methanol tolerance under acidic conditions.