Synthesis, electrochemical characterization and molecular dynamics studies of surface segregation of platinum nano-alloy electrocatalysts.

Alloy Pt-M (M = Co, Ni) nanocatalysts, supported on carbon Vulcan XC-72, were synthesized using the carbonyl chemical route. A high dispersion on such substrate was revealed by transmission electron microscopy (TEM). Alloy formation on the nanometre scale length was shown by high-resolution transmission microscopy (HRTEM) and energy dispersive X-ray spectroscopy (EDX) on a nanoparticle. The metal M in Pt-M nanoalloys segregates preferentially on the nanoparticles' surface, as determined by the hydrogen adsorption electrochemical reaction. An increased tolerance towards methanol of such nanoalloy materials was observed for the oxygen reduction reaction (ORR) in acid media. To better understand the structure and segregation phenomena of these nanoalloys, molecular dynamics (MD) with a self-optimized reactive force field was applied.