Molecular dynamics simulations of ternary PtxPdyAuz fuel cell nanocatalyst growth

Abstract

Molecular dynamics simulation of PEMFC cathodes based on ternary Pt 70 Pd 15 Au 15 and Pt 50 Pd 25 Au 25 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 25at%, surface Pt x Pd 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 x Pd y surface active sites. Core-shell nanocatalyst morphology changes occur due to impinging Pt kinetic energy confinement and dissipation.

Insights on the unique electro-catalytic behavior of PtBi/C materials

“…XRD patterns were recorded in the 20 ° ≤ 2θ ≤ 140 ° range (Figure 4). All the diffraction peaks were indexed to the face centered cubic (fcc) structure of Pt, and their position was found to be consistent with the JCPDS 04−0802 card for platinum except for the small peak at 2θ = 23.1° in all patterns and a massive of peaks centered at ca. 30° in the case of Pt0.8Bi0.2/C, which were attributed to the {002} set of planes of turbostratic graphite 34,35 and to the presence of isolated small (amorphous) Bi oxide clusters 36 , respectively.…”

“…Molecular dynamics (MDs) simulation is a very efficient method for the study of the growth and properties of nanoparticles, 22,23 because this method considers molecular scale processes.…”

Multiscale Molecular Dynamics Simulations of Fuel Cell Nanocatalyst Plasma Sputtering Growth and Deposition

“…To this end, many synthesis techniques such as plasma sputtering deposition have been investigated, including conventional magnetron, high-power impulse magnetron sputtering, and magnetron gas aggregation source depositions [4][5][6][7]. Since these deposition processes are of atomic nature, the description and insights into targeted growth processes to improve NP morphology, structure, and properties can successfully be explored using atomistic simulations, especially molecular dynamics [8][9][10][11][12][13][14][15][16]. Both growth in inert and reactive plasma environments has, thus, been shown feasible.…”

Pt3MeAu (Me = Ni, Cu) Fuel Cell Nanocatalyst Growth, Shapes, and Efficiency: A Molecular Dynamics Simulation Approach

“…Beyond the lowering of the platinum loading in the electrode catalytic layers, alloyed Pt-based materials display an improved catalytic activity towards the ORR [11], a better tolerance towards poisoning species [12,13] and, for some authors, an enhanced durability under fuel cell working conditions [14]. Addition of Au was indeed proposed to improve the durability of Pt-based nanocatalysts [14][15][16][17][18][19][20][21][22][23]. Nevertheless, only few fundamental studies on such kind of catalysts are available.…”