Nitrogen-Doped Porous Carbons from Lotus Leaf for CO2 Capture and Supercapacitor Electrodes

In this work, N-doped porous carbons were synthesized by a one-step sodium amide activation of carbonized lotus leaf at 450–500 °C. The CO2 adsorption properties of the as-synthesized carbonaceous materials were carefully investigated. In addition, the supercapacitor performance of the optimized sample was also preliminarily explored to examine its potential as the electrode material. These lotus leaf-derived carbons possess good CO2 adsorption capacity up to 3.50 and 5.18 mmol/g at 25 and 0 °C under atmospheric pressure, respectively. It was found that the synthetic effects of narrow microporosity, N content, pore size, and pore size distribution of the sorbents decide their CO2 adsorption abilities under the ambient conditions. These lotus leaf-based carbons also demonstrate many excellent CO2 adsorption properties, such as good selectivity of CO2 over N2, quick adsorption kinetics, moderate heat of adsorption, excellent recyclability, and high dynamic adsorption capacity. In addition, preliminary electrochemical studies show that the optimized sample has high capacitance (266 F/g) and excellent stability in cycling tests. These results indicate these lotus leaf-derived N-doped porous carbons have good potential in the application of CO2 capture and supercapacitor.