Nanoarchitectonics of hydrogel-derived ultrahigh surface area nanoporous carbon materials with enhanced supercapacitance performance

Abstract In the era of the decarbonization economy, supercapacitors offer a realistic solution to the energy storage problem due to their rapidly chargeable electrical double layers. Here, we present the energy performance of ultrahigh surface area nanoporous carbon materials having abundant hierarchical micro/mesopores obtained by in situ potassium carbonate (K2CO3) activation of polyacrylamide (PAM) hydrogel. The resulting nanoporous carbon materials obtained by the carbonization of the hydrogel in the temperature range 600 to 900 °C possess high Brunauer–Emmett–Teller surface areas up to ca. 3,038 m2 g−1 for the material prepared at 800 °C (PAM4-K800). Electron microscopy analyses revealed the formation of micro/mesoporous amorphous carbon structures. Surface composition and nitrogen and oxygen doping of the carbon matrix were verified by X-ray photoelectron spectroscopy. The electrochemical supercapacitance performance was tested using a 3-electrode system in an aqueous electrolyte (1 M H2SO4). The optimal sample (PAM4-K800) achieved the highest specific capacitance value of 313.3 F g−1 at a current density of 1 A g−1, with excellent capacitance retention of 97.5% after 10,000 charge/discharge cycles. Furthermore, a symmetric supercapacitor device prepared using the optimum material delivered a high energy density of 12.3 Wh kg−1 at a power density of 309.4 W kg−1 and an outstanding cycle life of 95.9% after 10,000 cycles. The outstanding electrochemical performance of PAM hydrogel-derived carbon materials makes them promising candidates for high-performance supercapacitor applications.