Oxygen reduction reaction on carbon-supported palladium nanocubes in alkaline media

• Carbon-supported Pd nanocubes of three different size were synthesized.
• Specific activity of Pd nanocubes is higher than that of spherical Pd nanoparticles.
• The mass-activity of ~ 7 nm Pd nanocubes matches that of commercial Pd/C.
• The oxygen reduction reaction on Pd nanocubes proceeds via 4-electron pathway.

Carbon-supported Pd nanocubes with the size of 30, 10 and 7 nm were prepared and their electrocatalytic activity towards the oxygen reduction reaction (ORR) in alkaline solution was studied. For comparison carbon-supported spherical Pd nanoparticles and commercial Pd/C catalyst were used. The catalysts were characterised by transmission electron microscopy, electro-oxidation of carbon monoxide and cyclic voltammetry and the ORR activity was evaluated using the rotating disk electrode method. The ORR on all studied Pd/C catalysts proceeded via four-electron pathway where the rate-limiting step was the transfer of the first electron to O2 molecule. The specific activity of Pd nanocubes was more than two times higher than that of spherical Pd nanoparticles and increased with increasing the particle size.

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