Unexpectedly high stability and surface reconstruction of PdAuAg nanoparticles for formate oxidation electrocatalysis

High-performance Pd-based nanocatalysts for alkaline methanol and formate fuel cells have stimulated widespread attention. Hence, a series of ternary Pd-Au-Ag nanoalloys have been synthesized on carbon nanotubes, which demonstrate promising activity and unexpectedly high stability for the formate oxidation reaction (FOR) in alkaline medium. The ternary Pd 3 Au 3 Ag 1 nanoalloy catalyst showed an initial mass activity of 4.51 A mg Pd −1 and a retained mass activity of 1.32 A mg Pd −1 after chronoamperometric measurement for 3600 s, which are superior to the best values for all FOR catalysts reported so far. The Pd 3 Au 3 Ag 1 catalyst also showed a good specific activity of 4.32 mA cm −2 for the methanol oxidation reaction. Furthermore, surface reconstruction of the Pd 3 Au 3 Ag 1 nanoalloy was observed during FOR, where the activity of Pd 3 Au 3 Ag 1 catalysts increased up to 33% and the cycling durability retained 55% after cyclic voltammetry with the upper potential of 1.7 V. The FOR enhancement is attributed to the formation of mixed oxidation-state Ag sites and the increase in the Pd surface coverage, and provides a new prospect for the design of ternary nanoalloy electrocatalysts for various fuel oxidation reactions. Pd 3 Au 3 Ag 1 NPs on carbon nanotubes undergo a potential-driven surface reconstruction that improves the activity and durability for the electrocatalytic formate oxidation reaction.