Interatomic diffusion in Pd-Pt core-shell nanoparticles

Publication date: May 2020Source: Chinese Journal of Catalysis, Volume 41, Issue 5Author(s): Yanfeng Zhang, Shangqian Zhu, Lili Zhang, Dong Su, Minhua ShaoAbstractPt monolayer-based core-shell catalysts have garnered significant interest for the application of low temperature fuel cell technology as their use may enable a decreased loading of Pt while still providing sufficient current density to meet volumetric requirements. One promising candidate in this class of materials is a Pd@Pt core-shell catalyst, which shows enhanced activity toward oxygen reduction reaction (ORR). One concern with the use of Pd@Pt, however, is the durability of the core-shell structure as Pd atoms are thermodynamically favored to migrate to the surface. The pathway of the migration has not been systematically studied. The current study explores the stability of this structure to thermal annealing and probes the effect of this heat treatment on the catalyst surface structure and its oxygen reduction activity. It was found that surface alloying between Pd and Pt occurs at temperatures as low as 200 °C, and significantly alters the structure and ORR catalytic activity in the range of 200–300 °C. Our results shed lights on the thermal induced interatomic diffusion in all core-shell and thin film structures.Graphical AbstractThe Pd@Pt core-shell structure can be destroyed by thermal annealing lowering the activity toward oxygen reduction reaction.
Source: Chinese Journal of Catalysis - Category: Chemistry Source Type: research