Synthesis of ultra-high nitrogen doped hollow mesoporous carbon nanospheres via a universal solid–liquid interface self-assembly strategy

Functional mesoporous polymers, particularly their derived hollow mesoporous carbon spheres (HMCS), have introduced new opportunities in the field of energy storage. Traditional synthesis methods for HMCS typically rely on chemical etching, which often results in uniform chemical properties and structural control, thereby limiting their application in large-scale production and diverse fields. Therefore, in this study, we report a novel strategy for obtaining HMCS through the direct pyrolysis of a core matrix, melamine–formaldehyde resin (MF), to achieve hollow structures and ultra-high nitrogen doping (approximately 14.8 wt%). This new solid–liquid interfacial self-assembly approach enables the production of HMCS with remarkable electrochemical performance and practical application prospects in sodium-ion half-cells and full cells, thanks to the high nitrogen doping and unique structure. Notably, this strategy has been validated for its general applicability across 1D, 2D, and 3D solid matrices. Additionally, by adjusting the calcination temperature, this method allows for precise control over both the core size and nitrogen content of the egg yolk-shell structure mesoporous carbon spheres. In summary, the mesoporous materials developed in this study demonstrate flexibility, simplicity, versatility, and structural diversity, offering significant insights for future applications in energy storage and other fields.