Hierarchical confinement of PtZn alloy nanoparticles and single-dispersed Zn atoms on COF@MOF-derived carbon towards efficient oxygen reduction reaction

Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) are attracting significant attention for their enormous range of applications because of their designable and controllable skeletons and porosities. Integrated MOF/COF materials are well developed in gas absorption, photocatalysis, and chemical sensors. Here, an ultrastable COF@MOF-derived catalyst has been first synthesized, in which hollow carbon acts as a support to confine Pt-Zn intermetallic nanoparticles and isolated Zn atoms. The COF on the surface of the MOF facilitates the construction of a hollow structure, and the MOF prevents the collapse and aggregation of the COF coating in the pyrolysis process. The resulting catalyst has Pt-Zn intermetallic nanoparticles with an average size of 3 nm supported on the hollow carbons with atomic Zn distributions. Based on the combination of the active Zn atoms and Pt-Zn clusters/nanoparticles, the catalyst displays high catalytic activity towards ORR with half-wave potentials of 0.85 and 0.85 V, which were more positive than those of Pt/C in alkaline and acidic conditions, respectively. More importantly, the catalyst exhibits excellent long-term stability over 20 hours. This work provides new guidance for designing core-shell MOF/COF materials for electrocatalysts, which is key to systems for energy conversion and storage.

Automated summary

Covalent organic frameworks (COFs) and metal-organic frameworks (MOFs) have been extensively studied for their designable and controllable structures, which can be used in a wide range of applications. A new COF@MOF-derived catalyst with high stability and catalytic activity for oxygen reduction reaction has been successfully synthesized, demonstrating excellent long-term stability.