Pd nanoparticles embedded in N-Enriched MOF-Derived architectures for efficient oxygen reduction reaction in alkaline media

Developing high efficient Pd-based electrocatalysts for oxygen reduction reaction (ORR) is still challenging for alkaline membrane fuel cell, since the strong oxygen adsorption energy and easy agglomerative intrinsic properties. In order to simultaneously solve these problems, Pd/Co3O4–N–C multidimensional materials with porous structures is designed as the ORR catalysts. In details, the ZIF-67 with polyhedral structure was firstly synthesized and then annealed at high-temperature to prepare the N-doped Co3O4 carbon-based material, which was used to homogeneously confine Pd nanoparticles and obtained the Pd/Co3O4–N–C series catalysts. The formation of Co–N and C–N bond could provide efficient active sites for ORR. Simultaneously, the strong electronic interaction in the interface between the Pd and N-doped Co3O4 could disperse and avoid the agglomeration of Pd nanoparticles and ensure the exposure of active sites, which is crucial to lower the energy barrier toward ORR and substantially enhance the ORR kinetics. Hence, the Pd/Co3O4–N–C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability in 0.1 mol L−1 KOH solution compared with Co3O4–N–C and Pd/C. The scalable synthesis method, relatively low cost, and excellent electrochemical ORR performance indicated that the obtained Pd/Co3O4–N–C electrocatalyst had the potential for application on fuel cells. The zeolitic imidazolate frameworks (ZIF-67) were employed as self-sacrificial precursors to prepare N-doped Co3O4 carbon-based materials, which could anchor the Pd nanoparticles. The obtained Pd/Co3O4–N–C exhibited excellent ORR catalytic performance, high Pd mass activity, and long-term durability. [Display omitted] •Zeolitic imidazolate frameworks (ZIF-67) were employed as self-sacrificial precursors.•Strong electronic interactions between the interface avoid the agglomeration of Pd nanoparticles and favor the exposure of active sites.•The Pd/Co3O4–N–C nanohybrids exhibit superior ORR performance, high Pd mass activity and excellent durability.