Sustainable N-doped hierarchical porous carbons as efficient CO2 adsorbents and high-performance supercapacitor electrodes

Abstract

Herein, a series of ACs are prepared with and without nitrogen doping at two different activation temperatures i.e., 800 °C and 900 °C. As-prepared ACs possess a high surface area (1142 - 2211 m2 g−1), large total pore volume (0.641 - 2.018 cm3 g−1), and a well-developed porous structure. At 1 bar, ACs demonstrate a remarkable CO2 uptake of 2.86 - 6.90 mmol g−1 at 273 K and 2.22 - 4.71 mmol g−1 at 298 K. This is attributed to the large ultra-micropore volume of pore size (< 0.73 nm), a prerequisite for achieving high CO2 adsorption. Finally, ACs based electrodes used for supercapacitors display high specific capacitance (100 - 204 Fg−1 at 0.5 Ag−1), and outstanding stability (∼ 92 % capacity retained even after 1000 cycles). It is shown that glucose-derived carbon precursor activated by potassium hydroxide at 900 °C denoted as “CK-900” proves to be the best sample for CO2 adsorption due to its narrow pore size, whereas glucose derived carbon precursor with melamine (acts as a nitrogen doping material) activated by potassium hydroxide at 900 °C denoted as “CNK-900” exhibits the best supercapacitive characteristics owing to its wider pore size distribution, high pore volume, and optimum nitrogen content. The remarkable CO2 uptake and energy storage capacities are attributed to high surface area, optimum nitrogen doping, and micro-mesopores volume of ACs framework.