NaCl sealing Strategy-Assisted synthesis CoO-Co heterojunctions as efficient oxygen electrocatalysts for Zn air batteries

Developing highly efficient, low-cost, and stable bifunctional oxygen electrocatalysts is essential for the wide popularization of rechargeable Zn-air batteries. Combining zero-dimensional metal nanoparticles with two-dimensional metal oxide nanosheets is an appealing strategy to balance performance and cost. However, the precise construction of these composites remains a great challenge, and their interaction mechanisms lack thorough study. Herein, a cobalt-oxide-based bifunctional oxygen electrocatalyst comprising a rich Co-CoO heterointerface (CoO/Co@NG) was synthesized via a NaCl sealing-assisted pyrolysis strategy. The NaCl crystals played the role of a closed nanoreactor , which facilitated the formation of a CoO-Co heterojunction . Experimental results and theoretical calculations confirmed that the ingeniously constructed heterojunction expedited the oxygen reduction reaction and oxygen evolution reaction kinetics, which is superior to Pt/C. When serving as the air electrode in an assembled liquid-state Zn-air battery , the battery shows high power density (215 mW cm −2 ), specific capacity (710 mAh g zn −1 ), and outstanding durability (720 h at 10 mA cm −2 ). This work provides an innovative avenue to design high-performance heterojunction electrocatalysts for perdurable Zn-air batteries.