Preparation of N-doped nanoporous carbon from ZIF-8 metal-organic framework via ultrasonic spray pyrolysis

N-doped nanoporous carbon (NPC) was synthesized from ZIF-8 metal–organic framework via a one-step ultrasonic spray pyrolysis (USP) process and evaluated as a supercapacitor electrode material. The USP method involves ultrasonic nebulization of a ZIF-8 suspension, formation of agglomerates by preheating the droplets, and carbonizing the agglomerates at 1100 °C to yield USP-NPC. For comparison, conventional ZIF-8-derived NPC (c-NPC) and spray-dried ZIF-8 derived NPC (SD-NPC) were also prepared. USP-NPC consists of spherical dense submicron particles with a BET surface area of 1059 m²/g and high N content (6.4 at%). Electrochemical tests revealed that USP-NPC exhibited superior supercapacitance performance (249.7F/g at 0.5 A/g) and 10000-cycles durability compared to c-NPC and SD-NPC. The enhanced performance of USP-NPC is attributed to its spherical morphology, high surface area, and rich N-doping. This study demonstrates that the USP method is a promising approach for the facile synthesis of high-performance NPC electrode materials for supercapacitor applications.