Heterogeneous interface engineering to enhance oxygen electrocatalytic activity for rechargeable zinc–air batteries

The electrocatalytic activity of catalysts can be significantly enhanced through the utilization of heterogeneous structures. Nevertheless, the optimization of both catalytic activity and durability via heterojunction engineering remains a considerable challenge. In this work, we fabricated electrocatalysts of Co/CoO heterojunctions on a highly porous hollow carbon material. The formation of heterojunctions increases the abundance of accessible active sites and optimizes the electrocatalytic reaction kinetics and reactivity. Thus, the prepared catalysts (Co/CoO@N–C-40) deliver robust and stable bifunctional oxygen electrocatalytic activity during the oxygen reduction/evolution reaction (ORR/OER) process. The performance of rechargeable zinc–air batteries (ZABs) greatly depends on bifunctional oxygen electrocatalysts, which are crucial for efficient charging and discharging processes. Consequently, the Co/CoO@N–C-40-based ZABs have superior cycling stability (750 h) and show a stable energy efficiency of 55.10% at 10 mA cm⁻² (53.46% after 555 h). This work offers a high-quality oxygen electrocatalyst for ZABs and extends the application of heterogeneous interfacial catalysts in various energy storage and conversion devices.