Porous carbon materials have drawn tremendous attention due to its applications in energy storage, gas/water purification, catalyst support, and other important fields. However, producing high-performance carbons via a facile and efficient route is still a big challenge. Here we report the synthesis of microporous carbon materials by employing a steam-explosion method with subsequent potassium activation and carbonization of the obtained popcorn. The obtained carbon features a large specific surface area, high porosity, and doped nitrogen atoms. Using as an electrode material in supercapacitor, it displays a high specific capacitance of 245 F g(-1) at 0.5 A g(-1) and a remarkable stability of 97.8% retention after 5000 cycles at 5 A g(-1). The product also exhibits a high CO2 adsorption capacity of 4.60 mmol g(-1) under 1066 mbar and 25 °C. Both areal specific capacitance and specific CO2 uptake are directly proportional to the surface nitrogen content. This approach could thus enlighten the batch production of porous nitrogen-doped carbons for a wide range of energy and environmental applications.