Palladium–iridium nanowires for enhancement of electro-catalytic activity towards oxygen reduction reaction

• Palladium–iridium nanowires were synthesized via a facile hydrothermal process.
• The nanowires show high uniformity in diameter (1.5–2.0 nm) and rough surface.
• The Pd–Ir nanowires display high ORR activity and durability in acid media.
• Electron transfer numbers for oxygen reduction reaction are close to four.

In this work, palladium–iridium nanowires with a Pd/Ir atomic ratio of 2/1 are synthesized through a facile hydrothermal method. Transmission electron microscopy images show that the palladium–iridium nanowires have a uniform diameter below 2 nm and a rough surface with many atomic steps. The electro-catalytic performance of the carbon supported palladium–iridium catalyst towards oxygen reduction reaction has been examined in 0.1 M HClO4 solution. The carbon supported palladium–iridium catalyst displays comparable catalytic activity but much higher durability in comparison with those of the commercial carbon supported platinum catalyst. The excellent electro-catalysis might be attributed to the high accessible area, rough surface and iridium introduction. The work demonstrates that palladium–iridium nanocrystals are promising electro-catalysts for oxygen reduction electro-catalysis in acid media.

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