Boosting oxygen reduction catalysis with abundant single atom tin active sites in zinc-air battery

Abstract Zinc (Zn)-air battery provides us an option to address both energy conversion and environment pollution issues. Herein, we successfully synthesized a type of Sn–N–C single atom catalyst and tailored the loading mass of single atom Sn. Sn1–N–C with the highest Sn loading mass exhibits the highest oxygen reduction reaction (ORR) activity (0.87 V vs. RHE for half-wave potential), near 4 e− selectivity, and excellent durability. Furthermore, Sn1–N–C based home-made Zn-air battery with a power density of 161 mW·cm−2 at 250 mA·cm−2 outperforms the one assembled from 20 wt.% Pt/C (63 mW·cm−2 at 140 mA·cm−2) and shows superior stability (can last at least for 20 days until the overall consuming of 1 mm thick zinc plate), rendering it to be a promising alternative to replace noble metal Pt. The atomically dispersed Sn catalyzes ORR process via the 2 e− + 2 e− consequential pathway. This work potentially opens the door to provide valuable insights and principles for rational design of single atom Sn catalysts in Zn-air battery.