Yuang Xiong

N-doped carbon aerogels have garnered increasing research interest in the field of energy and environment due to their unique structural features. Organic dyes, which contain redox-active sites and act as pollutants, are attractive candidates for cathode materials in Li-ion batteries but still suffer from poor cycle stability and rate performance. Therefore, there is still a lack of an easy and effective approach to rationally design the pore structure of N-doped carbon aerogels for efficiently and stably trapping dye molecules and converting them into high-performance cathode materials. Herein, we propose an innovative strategy for preparing nitrogen-doped carbon aerogels with a well-defined micropore structure (MNCAs) for efficient adsorption of dye molecules, subsequently converting them into high-performance lithium-ion battery cathode materials. MNCAs were synthesized via Schiff-based polymerization using polyhedral oligomeric silsesquioxane (POSS) as a template, resulting in a carbon framework with well-defined micropores. Benefiting from their high specific surface area and well-defined micropore structure, MNCAs exhibited a maximum adsorption capacity at equilibrium of 2273 mg g⁻¹ for indigo. Notably, the indigo@nitrogen-doped carbon aerogel composite (IDG@MNCAs) exhibits high specific capacity, outstanding cycling stability, and remarkable rate capability. The discharge specific capacity of IDG@MNCAs retains 89% of its capacity (120 mAh g⁻¹) after 200 cycles at 100 mA g⁻¹ and maintains 70% capacity retention after 1200 cycles at the higher current density of 1000 mA g⁻¹, surpassing many recently reported organic cathode materials.

Fe-N-C materials have been regarded as one of the potential candidates to replace traditional noble-metal-based electrocatalysts for the oxygen reduction reaction (ORR). It is believed that the structure of carbon support in Fe-N-C materials plays an essential role in highly efficient ORR. However, precisely designing the morphology and surface chemical structure of carbon support remains a challenge. Herein, we present a novel synthetic strategy for the preparation of porous carbon spheres (PCSs) with high specific surface area, well-defined pore structure, tunable morphology and controllable heteroatom doping. The synthesis involves Schiff-based polymerization utilizing octaaminophenyl polyhedral oligomeric silsesquioxane (POSS-NH₂) and heteroatom-containing aldehydes, followed by pyrolysis and HF etching. The well-defined pore structure of PCS can provide the confinement field for ferroin and transform into Fe-N-C sites after carbonization. The tunable morphology of PCS can be easily achieved by changing the solvents. The surface chemical structure of PCS can be tailored by utilizing different heteroatom-containing aldehydes. After optimizing the structure of PCS, Fe-N-C loading on N,S-codoped porous carbon sphere (NSPCS-Fe) displays outstanding ORR activity in alkaline solution. This work paves a new path for fabrication of Fe-N-C materials with the desired morphology and well-designed surface chemical structure, demonstrating significant potential for energy-related applications.