Size-dependent oxygen reduction property of octahedral Pt-Ni nanoparticle electrocatalysts

The size effect on the electrocatalytic property of octahedral Pt-Ni alloy nanoparticles in the oxygen reduction reaction (ORR) was studied by making particles with different sizes and conducting electrochemical measurements. Octahedral Pt-Ni nanoparticles on carbon support (Pt-Ni/C) were produced using a facile and surfactant-free solid-state chemistry method. Two groups of octahedral Pt-Ni/C, including Pt3Ni/C and Pt1.5Ni/C, with particle size ranging from around 4 to 8 nm were prepared. Both the ORR activity and the stability of the two group catalysts were studied, which exhibited varying dependence over the particle size. The different relationships between the Pt-Ni size and the ORR property were investigated and attributed to alterations in the particle electronic/geometric structure and the Ni leaching behaviour.