Easily tunable hydrogel-derived heteroatom-doped hierarchically porous carbons as multifunctional materials for supercapacitors, CO2 capture and dye removal

Abstract

It is attractive to develop multifunctional materials for practical applications. Herein, heteroatom-doped hierarchically porous carbons (HPCs) are prepared through a simple pyrolysis of monolithic hydrogels derived from glucose, followed by chemical activation using KOH as an activator at 600–1000 °C. With different activation temperature, the pore structure and surface chemistry of the resulting HPCs can be easily tuned and the corresponding performances in supercapacitors, CO2 capture and dye adsorption are further investigated. HPC800 with the largest micropore volume (0.58 cm3 g−1) exhibits a high specific capacitance of 249 F g−1 at 1 A g−1 and an excellent cycling stability with 94% of the capacitance retention after 1000 cycles as supercapacitors electrodes. Meanwhile, HPC800 shows the remarkable adsorption capacity of CO2 (4.4 mmol g−1 at 25 °C, 1 atm). For methylene blue (MB) adsorption, the maximum adsorption capacity of 720 mg g−1 is obtained on HPC1000 with the highest specific surface area (2302 m2 g−1) and total pore volume (1.10 cm3 g−1). The CO2 and MB adsorption capacities are both higher than most of the reported adsorbents. It is demonstrated that CO2 and MB adsorption capacity are determined by the volume of pore with diameter <0.8 and 2.8 nm, respectively (both about 2.4 times larger than the size of adsorbates). The prepared HPCs are promising candidates for practical applications in both energy-related and environmental fields.