A Stable Rechargeable Aqueous Zn-Air Battery Enabled by Heterogeneous MoS 2 Cathode Catalysts.

Aqueous rechargeable zinc (Zn)-air batteries have recently attracted extensive research interest due to their low cost, environmental benignity, safety, and high energy density. However, the sluggish kinetics of oxygen (O 2 ) evolution reaction (OER) and the oxygen reduction reaction (ORR) of cathode catalysts in the batteries result in the high over-potential that impedes the practical application of Zn-air batteries. Here, we report a stable rechargeable aqueous Zn-air battery by use of a heterogeneous two-dimensional molybdenum sulfide (2D MoS 2 ) cathode catalyst that consists of a heterogeneous interface and defects-embedded active edge sites. Compared to commercial Pt/C-RuO 2 , the low cost MoS 2 cathode catalyst shows decent oxygen evolution and acceptable oxygen reduction catalytic activity. The assembled aqueous Zn-air battery using hybrid MoS 2 catalysts demonstrates a specific capacity of 330 mAh g -1 and a durability of 500 cycles (~180 h) at 0.5 mA cm -2 . In particular, the hybrid MoS 2 catalysts outperform commercial Pt/C in the practically meaningful high-current region (>5 mA cm -2 ). This work paves the way for research on improving the performance of aqueous Zn-air batteries by constructing their own heterogeneous surfaces or interfaces instead of constructing bifunctional catalysts by compounding other materials.