Molecular dynamics simulations of ternary PtxPdyAuz fuel cell nanocatalyst growth

Molecular dynamics simulation of PEMFC cathodes based on ternary Pt₇₀Pd₁₅Au₁₅ and Pt₅₀Pd₂₅Au₂₅ nanocatalysts dispersed on carbon indicate systematic Au segregation from the particle bulk to the surface, leading to an Au layer coating the cluster surface and to the spontaneous formation of a Pt@Pd@Au core-shell structure. For Au content below 25 at%, surface Pt_xPd_y active sites are available for efficient oxygen reduction reaction, in agreement with DFT calculations and experimental data. Simulations of direct core@shell system prepared in conditions mimicking those of plasma sputtering deposition pointed out an increase of the number of accessible Pt_xPd_y surface active sites. Core-shell nanocatalyst morphology changes occur due to impinging Pt kinetic energy confinement and dissipation.