Built-in Electric Field in 1D/2D Heterostructure Boosts Zinc Air Battery Performance.

The realization of a rechargeable zinc-air battery (ZAB) is hindered by the low intrinsic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities. In this work, an abundant built-in electric field is noticed in a 1D/2D CoO/CoS heterostructure, triggering electron transfer from CoO to CoS associated with a downshifted d band center of the Co atom mitigating the strong electrochemical adsorption of *OH species on active sites; thereby, boosted OER and ORR performance are achieved. Namely, the OER specific activity of CoO/CoS is enhanced by 3.8- and 2.2-fold compared to the counterpart of CoO and CoS, respectively. Furthermore, the kinetic current density of CoO/CoS, a fingerprint of intrinsic ORR activity, is promoted by 46 and 6.6 times relative to CoO and CoS. The rechargeable ZAB performance attains 215.6 mW cm, 1.6-times better than Pt/C-IrO. Moreover, the superior performance remained for 600 h. Besides, the battery performance of the all-solid-state ZAB reaches 83.8 mW cm, revealing its promising application in wearable device.