Nanoarchitectonics of Nanoporous Carbon Materials from Achyranthus bidentata (Datiwan) Stem for Supercapacitor Applications.

Biomass is a sustainable carbon source to produce porous carbon materials. Due to the high surface area, tunable porosity, surface functionalities and high chemical stability, biomass carbons have extensively explored in sensing, separation, and energy storage and conversion applications. Here, we report on the fabrication of nanoporous activated carbon materials from a novel biomass precursor Achyranthus bidentata (Datiwan), using a low-energy method (carbonized at 500 °C). The effects of chemical activators (phosphoric acid (H3PO4), potassium hydroxide (KOH), and zinc chloride (ZnCl2) on surface textural properties and energy storage capacity were systematically studied. The H3PO4 and ZnCl2 activated samples (DAC-H500, DAC-Z500) exhibited the specific surface area of 724 and 758 m2 g-1, respectively, and retained abundant surface oxygen functionalities, thereby leveraging decent specific capacitance of 201 F g-1 and 140 F g-1 at 1 A g-1 with 51 % and 61.3 % retention of their initial capacitance values at 10 A g-1. The symmetric cell assembled with the DAC-Z500 delivered 3.5 Wh kg-1 energy density at a power density of 590 W kg-1 with good cycle life of 76 % and 98 % coulombic efficiency after 10,000 consecutive charge/discharge cycles. Datiwan, a self-grown, abundant biomass that is indirectly contributing to carbon emissions, is being utilized to prepare nanoporous carbon at a lower temperature, and it shows significant potential as an electrode material in energy storage applications.