Preparation,Characterization And Properties Of Loofa Sponge And Tremella-Derived Porous Carbons

Porous carbons derived from biomass are widely used in the fields of absorption, separation, energy storage and catalysis because of their large specific surface area, rich surface functional groups, renewable and pollution-free raw materials. The pore structure parameters, specific surface area and surface chemistry of porous carbon play the most important role in application performance, which is closely related to the characteristics of the precursors and preparation process. Therfore, selecting proper biomass precursor and preparation method to control the physicochemical properties of materials and studying the relationship between structure and properties are of great significance.In this paper, porous carbon sheets were obtained via the H2O2 and EDTA-2Na pre-treatment of two easily available biomass loofa sponge and tremella followed by carbonlization and KOH-activation. Influences of pre-treatment and KOH/carbon ratio on the pore structure and surface chemistry are systematically studied by means of XPS, elemental analysis, N2 adsorption-desorption and etc. Loofa sponge-derived porous carbons have an appropriate pore size distribution and open hole texture, the sample LSAC-3 which was synthesized with the alkali to carbon ratio of 3 has a BET specific surface area of 2402 m2 g-1, pore size distributes from 0.7 nm to 2.7 nm, all levels of the channel are interconnected with each other, and the surface is rich in oxygen containing functional groups and therefore exhibits good capacitance performance and high cycling stability. It displays a remarkable electrochemical performance with a substantially high specific capacitance of 499 F g-1 at 0.1 A g-1 in three-electrode system with 6 M KOH as electrolyte, good rate capability with a specific capacitance of 303 F g-1 at 10 A g-1, and excellent cycling stability with only 8.7% capacitance loss over 10000 cycles at 5 A g-1. What’s more, the as-assembled symmetric supercapacitor delivers high energy density of 25.3 Wh kg-1 in 1 M SBP-BF4/AN electrolyte. Tremella-derived porous carbons have more mespores than Loofa sponge-drived carbon, the sample activated with KOH/carbon ratio of 5:1 possesses the high BET specific surface area of 3592 m2 g-1 and shows a very high specific capacitance of 525 F g-1 at 0.1 A g-1, extraordinary rate performance with a specific capacitance of 288 F g-1 at 15 A g-1; quite a number of micropores also makes Tremella-based porous carbon have good performance for CO2 adsorption at 0℃ and ambient pressure. The sample activated with KOH/carbon ratio of 2:1 exhibits a high CO2 adsorption performance of 5.44 mmol g-1.