Engineering Hierarchically Porous Carbon Using a Facile Process: Assessment for Green Electrodes

Abstract

Production of carbonaceous materials from waste biomass is currently gaining much attention in scientific community due to the encouragement towards a sustainable approach. However, severe pretreatment processes are still the main challenging tasks. Herein, water hyacinth (WH) is used as a precursor. Hydrothermal carbonization in acidic conditions followed by thermal activation was used for the pretreatment. A novel chemical activator CH₃COOK was employed and compared to traditional chemical activators such as ZnCl₂ and K₂CO₃. High surface areas and numerous micropores of synthesized carbons are found in ZnCl₂ activation, while carbon compounds produced from K₂CO₃ and CH₃COOK possess modest surface areas but hierarchically micro-meso-structured carbon. These findings demonstrate that the CH₃COOK could serve as both a reagent for acid-assisted hydrothermal carbonization and a doped chemical for thermal activation. The use of CH₃COOK is more ecologically and economically friendly, confirmed by reduced chemical usage and less produced wastewater. Furthermore, because the obtained carbons include a large number of nitrogen contents of around 2.0 wt%, these hierarchically porous carbons could enhance their performances as electrode materials in energy storage applications.

Keywords: Water hyacinth, Hydrothermal carbonization, Biomass conversion, Hierarchical porous carbon, Potassium acetate