Gram-Scale-Synthesized Pd₂Co-Supported Pt Monolayer Electrocatalysts for Oxygen Reduction Reaction

Gram-scale synthesis of PtML electrocatalysts with a well-defined core−shell structure has been carried out using method involving galvanic displacement of an underpotential deposition Cu layer. The Pt shell thickness can be controlled by stepwise deposition. The Pt@Pd2Co/C nanoparticles were characterized by X-ray powder diffraction, aberration-corrected scanning transmission electron microscopy, high-resolution energy-loss spectrometry, and in situ X-ray absorption spectroscopy. A complete Pt shell of 0.6 nm on a Pd2Co core has been confirmed. The Pt@Pd2Co/C core−shell electrocatalysts showed a very high activity for the oxygen reduction reaction; the Pt mass and specific activity were 0.72 A mgPt−1 and 0.5 mA cm−2, respectively (3.5 and 2.5 times higher than the corresponding values for commercial Pt catalysts), at 0.9 V in 0.1 M HClO4 at room temperature. In an accelerated potential cycling test, a loss in active surface area and a decrease in catalytic activity for gram-scale-synthesized PtML catalysts were also determined.