Associating Co single atoms with RuO2 nanoparticles anchor on nitrogen-doped ultrathin porous carbon nanosheets as effective bifunctional oxygen electrocatalysts for rechargeable Zn–air batteries

Abstract

For developing rechargeable zinc–air batteries (ZABs), designing reasonably high-activity and robust endurance electrocatalysts toward oxygen evolution/reduction reactions (OER/ORR) is of paramount importance. Single-atom catalysts (SACs) have been considered as ideal candidates for driving oxygen electrocatalysis in ZABs owing to their high electrocatalytic activity and atom utilization. However, oxidation and aggregation hinder their practical application. To address this issue, Co single atom-decorated RuO₂ nanoparticles loaded on nitrogen-doped ultrathin porous carbon nanosheets (designated as Co_SA-RuO₂-NUCN) were synthesized. We provide an effective method for stabilizing cobalt atom with ruthenium dioxide; the strong interfacial interaction between Co_SA-RuO₂ makes the Co–O–Ru interface extremely stable in the electrocatalytic oxidation reaction. Meanwhile, Co_SA-RuO₂ combines with ultrathin carbon nanosheets to enhance the conductivity. Consequently, the obtained Co_SA-RuO₂-NUCN exhibits outstanding performance toward ORR (half-wave potential of 0.90 V) and OER (280 mV at 10 mA cm⁻²), respectively. Moreover, the rechargeable ZAB with Co_SA-RuO₂-NUCN shows high open-circuit voltage (1.55 V), ultrahigh specific capacity (766.14 mA h g⁻¹), and superb long-term cycling stability (800 h), outperforming the commercial Pt/C + RuO₂. This study not only presents a method to obtain a high-activity and strong stability electrocatalyst but also encourages to explore advanced materials to promote the development of ZABs.