DUT‐58 (Co) Derived Synthesis of Co Clusters as Efficient Oxygen Reduction Electrocatalyst for Zinc–Air Battery

Abstract

Abstract To meet the requirement of fuel cells and metal–air batteries, non‐noble metal catalysts have to be developed to replace precious platinum‐based catalysts. Herein, Co nanoclusters (≈2 nm) are anchored on nitrogen‐doped reduced graphene oxide (Co/N‐r‐GO) by using DUT‐58 (Co) metal–organic framework and GO as precursors. Compared with single‐atom catalysts usually with ultralow concentration (<0.5 wt%), Co nanoclusters are more beneficial to break the OO bond to ensure four electronic way for oxygen reduction reaction (ORR), since they can provide more adsorption centers for reactants. Therefore, as expected, the sample with 6.67 wt% Co content (Co/N‐r‐GO‐5%‐850) exhibits better ORR activity with a higher half‐wave potential of 0.831 V, a more positive onset potential of 0.921 V than Pt/C, and a comparable limiting current density in alkaline medium. The Co nanoclusters enhance the catalytic performance for ORR in three aspects: quantum size effects, metal–support interactions, and low‐coordination environment of metal centers. Furthermore, the sample is assembled into a zinc–air battery as the outstanding durable ORR catalyst. It displays a higher specific capacity (795 mAh g−1 at the current density 50 mA cm−2) and power density (175 mW cm−2) than Pt/C (731 mAh g−1 and 164 mW cm−2, respectively).

Keywords

• Co nanoclusters
• graphene oxide
• metal–organic framework
• oxygen reduction reaction
• zinc–air batteries