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

Abstract

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.

Nanoscale-faceting of metal surfaces induced by adsorbates

“…This has already been seen for various systems, such as Ag particles on a SiO 2 support, 6 nanoparticles of Au, Pt, Pd, or even PtNi alloys. 7,8 One way out of this dilemma of rather broad size and shape distributions might be the formation of well-defined nanostructures or facets on single-crystal surfaces, which provide a reproducible basis and model systems for studying structural sensitivity in (electro-)catalytic reactions. Examples for facet formation on small crystalline particles are well documented for supported metal catalysts 9,10 and oxide nanocrystals.…”

Molybdenum Doping Augments Platinum–Copper Oxygen Reduction Electrocatalyst

“…They hold much potential to address the most pressing issues with current Pt‐based fuel‐cell catalysts: high cost, limited longevity, and sluggish oxygen reduction reaction (ORR) kinetics in acidic media. Significant improvements over pristine Pt nanoparticle (NP) catalysts have been reported for bimetallic alloys, for which M=Co, Ni, Cu, Fe, and Cr or M=rare‐earth metal, such as Y . Abruña's group recently presented spherical Pt 3 Co NPs that showed a 200 % increase in terms of ORR mass activity with respect to Pt/C and other PtCo nanoalloys .…”

Synthesis of Carbon‐Supported Pt–YOx and PtY Nanoparticles with High Catalytic Activity for the Oxygen Reduction Reaction Using a Microwave‐based Polyol Method

“…Notable overviews of the development of ORR electrocatalysts have been presented by Gasteiger and Marković, Holade et al., and Shao et al . Recent reports have described that bimetallic Pt‐based alloyed nanoparticles on different substrates, such as Pt x M y (M=Ni, Co, Ti, Cu, W, Pd, Ag, Au, Rh, Zn, Sn, Fe, and Cr), show high ORR activity . In fact, PtCo alloy catalysts have been used in fuel cell automobiles (Mirai; Toyota Motor Corp.).…”