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.& COPY; 2022 Institute of Process Engineering, Chinese Academy of Sciences. Publishing services by Elsevier B.V. on behalf of KeAi Communications Co., Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

Developing efficient Pd-based electrocatalysts for alkaline membrane fuel cells poses challenges due to strong oxygen adsorption and easy agglomeration. To address these issues, Pd/Co3O4-N-C multidimensional materials with porous structures were designed as ORR catalysts. The formation of Co-N and C-N bonds provided efficient active sites while the electronic interaction between Pd and N-doped Co3O4 prevented agglomeration and ensured exposure of active sites, leading to enhanced ORR kinetics. The Pd/Co3O4-N-C nanocompounds exhibited excellent ORR catalytic performance, ideal Pd mass activity, and durability, indicating their potential for fuel cell applications.