Enhanced Oxygen Evolution Reaction and Zinc-Air Battery Performance Enabled by Chiral-Induced Spin Selectivity and Cobalt-Doped Nickel Oxide

The imminent demand to alleviate the global warming and considerable consumption of fossil fuel have promoted development of sustainable energy conversion systems such as rechargeable Zn–air batteries (ZABs) due to their superior energy density, excellent safety, and abundancy of Zn source. However, sluggish reaction kinetics of oxygen evolution reaction (OER) as well as low conductivity of generally exploited low-cost oxygen evolution catalysts have been challenges for developing competitive ZABs. Although ruthenium and/or iridium noble catalysts have been utilized because of their superior catalytic activity for OER, the high cost as well as efficiency loss derived from the electrochemical decomposition of active sites could pose a serious problem. Therefore, rational strategies to boost the OER catalytic activity of earth abundant catalyst, which is stable under severe anodic condition, are essential for the advanced rechargeable ZABs.<br/>Herein, we report a distinct approach using cobalt-doped nickel oxide (Co-NiO) with a chiral structure, obtained by a one-step hydrothermal process. Cobalt doping raises the conductivity as well as active site density of the catalyst, while the chiral structure triggers chiral-induced spin selectivity (CISS), which could boost the kinetic rates of OER by modulating the spin states of electrons to be aligned in a specific direction. The parallel alignment of spin configurations of electrons facilitates the production of triplet oxygen (³O₂), which is generated in a lower energy state than the singlet oxygen state (¹O₂), mitigating the overpotential for OER. Accordingly, our chiral Co-NiO-based electrode exhibited OER current density of 10 mA cm^–2 at 1.58 V versus the reversible hydrogen electrode, outperforming both achiral Co-NiO as well as undoped NiO. Furthermore, chiral Co-NiO-based rechargeable ZAB delivered a high open-circuit potential (1.57 V), low charge/discharge overpotential (0.79 V), and excellent operational stability for 100 h. Our findings represent a prominent pathway for the advancement of high-performance ZAB using low-cost OER catalyst mediated by CISS and hetero-atomic doping.