Robust Electronic Correlation of Co-CoN4 Hybrid Active Sites for Durable Rechargeable Zn-Air Batteries

The rational design of bifunctional catalysts with excellent activity and stability toward the oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is essential for rechargeable Zn-air batteries (ZABs). In this study, a facile coordination bridging strategy is proposed to construct bifunctional Co-CoN4 hybrid active sites embedded in porous N-rich carbon nanolamellas (denoted as Co-CoN4@NCNs) for both the ORR and OER. Synchrotron X-ray absorption spectroscopy and density functional theory calculations reveal that the increased intrinsic ORR/OER activities can be attributed to the efficient interfacial charge transfer between the atomic Co-N sites and metallic Co sites due to their robust electronic correlation. In situ Raman spectroscopy confirms that the OER activity depends on the CoOOH intermediates formed during the reaction. Co-CoN4@NCNs exhibits superior bifunctional catalytic performance for the ORR (E-1/2 = 0.83 V) and OER (eta = 310 mV at 10 mA cm(-2)) conducted in alkaline media. The assembled rechargeable Co-CoN4@NCNs-based ZAB displays an open-circuit voltage of 1.47 V, peak power density of 118.8 mW cm(-2), specific capacity of 776.7 mAh g(-1), and outstanding cycling stability over 1500 cycles. The regulation of the interfacial electronic properties can contribute to the rational design of bifunctional electrocatalysts used in rechargeable metal-air batteries.

Automated summary

In this study, bifunctional Co-CoN4 hybrid active sites embedded in porous N-rich carbon nanolamellas were successfully constructed through a facile coordination bridging strategy. The designed catalyst exhibited excellent activity and stability for both the ORR and OER, making it a promising candidate for rechargeable Zn-air batteries.