Hydrothermal Sol-Gel Synthesis of Monolithic Pyrrolic N-Doped Carbon Gels

Developing scalable strategies for carbon materials that simultaneously incorporate covalently bonded frameworks and chemically tunable surfaces remains a significant challenge. Here, we report a straightforward hydrothermal sol-gel process utilizing glucose and pyrrole precursors to produce monolithic N-doped carbon gels (MNCGs). By controlling synthesis duration, the morphology is precisely tuned from quantum dots to macroscopic monolithic hydrogels. The primary building blocks are 5 nm hydrophilic carbon dots featuring crystalline graphitic cores and amorphous shells with 2-10 wt.% nitrogen doping, predominantly composed of pyrrolic-N species (up to 80.21%). Following thermal activation at 700°C, MNCGs with a specific surface area of 448.72 m²/g and a pore volume of 0.50 cm³/g are obtained. Notably, the resulting gels demonstrate exceptional mechanical integrity, achieving a compressive strength of 1.42 mPa and a wear resistance of 95.83%. These robust monolithic frameworks provide significant advantages in noble metal catalysis, effectively preventing nanoparticle sintering, and in supercapacitors, exhibiting a high specific capacitance of 221.9 F/g (at 1 A/g) with a 61% retention rate at 100 A/g. This strategy resolves the traditional trade-off between structural integrity and surface functionality.