A Self-Sacrificing Dual-Template Strategy to Heteroatom-Enriched Porous Carbon Nanosheets with High Pyridinic-N and Pyrrolic-N Content for Oxygen Reduction Reaction and Sodium Storage

Controllable synthesis of 2D carbon nanosheets with high heteroatom-doping level, large specific surface area, and hierarchically pore structure is difficult and desired. In this work, a novel and simple self-sacrificing in situ formed dual-template strategy is first developed to synthesize N/S codoped hierarchically porous carbon nanosheets. The in-situ formed g-C₃N₄ and amorphous ZnO act as self-sacrificing templates on account of their thermal decomposition and evaporation at higher temperature. The N/S codoped hierarchically porous carbon nanosheets simultaneously possess high heteroatom-doping level (N: 10.51 wt%; S: 1.71 wt%), large specific surface area (904.63 m² g⁻¹), and abundant hierarchically porous structure. Particularly, this material possesses a high content of pyridinic-N and pyrrolic-N configuration (65.66%). These unique structure advantages of N/S codoped hierarchically porous carbon nanosheets contribute to high oxygen reduction electrocatalytic activity in both basic and acidic environments. Additionally, as the anode material for sodium-ion batteries, the material also displays a high reversible capacity of 270.1 mAh g⁻¹ at a current density of 100 mA g⁻¹ and high stability (160.1 mAh g⁻¹ after 2000 cycles at 1000 mA g⁻¹ with a capacity retention of 82.3%). These results indicate a great potential of the material in energy conversion and storage applications.