Construction of imide-linked covalent organic frameworks with palladium nanoparticles for oxygen reduction reaction

Covalent organic frameworks (COFs) have been widely employed as electrocatalysts for oxygen reduction reaction (ORR) due to their diverse and tunable skeletons and pores. However, their electrocatalytic activity was limited due to the lack of highly active catalytic sites. In this work, we have first immobilized palladium nanoparticles (NPs) into the crystal, porous, and stable imide-linked COF for ORR. The newly designed COF had pyridine linkers with imide-linkages in the frameworks serving as the binding sites to anchor Pd sites, and the high surface area and open pore channels provide fast mass transport pathway to the active Pd sites, which contributed highly active performance in ORR. And the designed catalyst delivered onset potential and the half-wave potential of COF-Pd of 0.97 and 0.83 V, with a limited current density of 6.1 mA cm⁻², respectively. This work provides us insights into developing high crystalline COFs with metal NPs in electrocatalytic systems.