The development of highly efficient bifunctional catalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is of paramount importance for rechargeable Zn-air batteries. Herein, cobalt (II) oxide (L-CoO) nanosheets with hierarchical nanostructures were grown on the stainless steel (SS) substrate via the facile heat treatment of 2D layered Co(OH)₂; and this binder-free 3D air electrode exhibits superior ORR/OER activity and stability (over 1000 h) in the rechargeable Zn-air flow battery. Importantly, X-ray absorption spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS) were employed to reveal the origins of the excellent bifunctional catalytic performance of this catalyst. Moreover, the evolution of the atomic-scale structures revealed by operando XAS strongly supports the excellent stability of L-CoO during electrocatalytic operation. Our work suggests a facile strategy to construct oxygen vacancy active sites; meanwhile, it offers a deep understanding at the atomic level on the excellent cycling stability in the Zn-air flow battery through X-ray spectroscopy.

对于可再充电的锌空气电池，开发用于氧还原反应（ORR）和氧释放反应（OER）的高效双功能催化剂至关重要。在此，通过对2D层状Co（OH）_2进行便捷的热处理，在不锈钢（SS）衬底上生长了具有分层纳米结构的氧化钴（II）纳米片（L-CoO）。; 这种无粘结剂的3D空气电极在可充电Zn空气流通电池中具有卓越的ORR / OER活性和稳定性（超过1000小时）。重要的是，采用X射线吸收光谱（XAS）和X射线光电子能谱（XPS）揭示了该催化剂优异的双功能催化性能的起源。此外，由操作XAS揭示的原子级结构的演变有力地支持了L-CoO在电催化操作过程中的出色稳定性。我们的工作提出了构建氧空位活跃位点的简便策略。同时，它通过X射线光谱学在原子水平上对Zn空气流通电池的出色循环稳定性提供了深刻的理解。