Adsorbate-Induced Segregation of Cobalt from PtCo Nanoparticles: Modeling Au Doping and Core AuCo Alloying for the Improvement of Fuel Cell Cathode Catalysts.

A sharp contrast in size dependence of the activity was revealed between PtCo/C and PtNi/C catalysts in the size range from 1.5 to 9 nm, with a subtle increase in activity for PtNi/C and a maximum for sizes between 6 and 7 nm, while PtCo/C catalysts showed a clear trend of decrease in activity with increasing particle size, peaking at the smallest sizes just above 2 nm in diameter. 18 Additionally, PtCo NPs of different compositions have already been synthesized and tested for satisfactory ORR activity within the 1.5–3.0 nm range. 66 , 67 Here, a magic number 147 atom cluster has been chosen as a representative model for PtCo catalyst system as it offers three levels to study the segregation events–core (central atom with surrounding first shell), subshell, and shell.

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