Isolated transition metal nanoparticles anchored on N-doped carbon nanotubes as scalable bifunctional electrocatalysts for efficient Zn-air batteries.

Accelerating the sluggish anode reaction in a Zn-air battery can improve its energy efficiency, but the large-scale development of this battery is hindered by the lack of bifunctional catalysts. Herein, we designed a one-step carbonization strategy for synthesizing monodispersed Co nanoparticles supported on N-doped carbon nanotube (Co/CNT), which shows excellent bifunctional electrocatalytic performance with long-term durability for oxygen reduction reaction/oxygen evolution reaction. The formation of carbon substrates from the carbonization of nitrogenous organic molecules are benefit to capture more Co nanoparticles though strong metal-substrate interaction, then construct high-density effective active sites of the Lewis base for accelerating the electrocatalytic reaction process. To verify its superior performance, a rechargeable Zn-air battery with a Co/CNT air electrode was subsequently constructed. The battery exhibits an open-circuit voltage of 1.41 V and a specific discharge capacity of 835.2 mAh/g, which can be continuously charged and discharged with good cycle stability. Our study provides a new strategy for developing various practical carbon-based non-noble metallic bifunctional electrocatalysts with promising performance in electrocatalysis and batteries to achieve the target of carbon neutrality.