Orthorhombic CoSe 2 nanoparticles anchored in Ketjenblack as a bifunctional electrocatalyst for Zn‐air batteries

Avoiding agglomeration of nanoparticles and regulating the electronic properties are highly essential methods to improve the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activities of catalysts and enhance the cycle stability of rechargeable metal-air batteries. Herein, orthorhombic CoSe2 nanoparticles anchored in acid-treated Ketjenblack (o-CoSe2/AK) nanoparticles have been synthesized via a hydrothermal reaction and selenization treatment, and exhibit excellent ORR and OER performance (a half-wave potential of 0.84 V for ORR and an overpotential of 380 mV at 10 mA cm−2 for OER). As a catalyst for a rechargeable Zn-air battery, it possesses a largest powder density of 122.0 mW cm−2. Surprisingly, o-CoSe2/AK has demonstrated outstanding stability and durability, especially superior to noble metals. The excellent bifunctional electrocatalytic performance is mainly ascribed to a large specific surface area, and metallic o-CoSe2 nanoparticles with a high dispersion anchored in the AK substrate surface, regulating the electronic structure.