Polyacrylamide Gel-Derived Nitrogen-Doped Carbon Foam Yields High Performance in Supercapacitor Electrodes

Porous carbons play a vital role in supercapacitor electrodes. The capacitive performance of porous carbons depends mostly on the pore structure and surface chemistry. It is highly desirable to develop robust methods to prepare porous carbons with controlled structures and compositions. Herein, a nitrogen-doped carbon foam was prepared on the basis of polyacrylamide gel with K₂CO₃ and K₂B₄O₇ as the activating agent and salt template, respectively. Due to the constraint effect of the cross-linked polyacrylamide network, K₂CO₃ and K₂B₄O₇ can be homogeneously embedded in the polymer matrix. The subsequent carbonization results in the nitrogen-doped carbon foam (PACF) with a hierarchically porous structure and high specific surface area (∼3404.8 m² g^–1). K₂B₄O₇ not only serves as the soluble salt template but can also reinforce the carbonaceous skeleton during carbonization. PACF yields an outstanding specific capacitance (346.9 F g^–1 at 0.5 A g^–1), good rate performance (224.4 F g^–1 at 50 A g^–1), and excellent cycle capability (retaining 97.2% of the initial capacitance after 10,000 consecutive charge–discharge cycles). This study demonstrates the potential of polyacrylamide gel as a promising carbon precursor and enriches the tool box for the preparation of porous carbons.