Solvent-induced molecular structure engineering of lignin for hierarchically porous carbon: Mechanisms and supercapacitive properties

Abstract

Lignin is considered an ideal precursor for porous carbon materials on account of its rich aromatic entities and high carbon content. Modulating the molecular structure of lignin is of paramount importance in controlling the carbon structure. In this work, a solvent-induced self-assembled strategy is reported to synthesize three porous carbon materials using three typical kinds of lignin as precursors. The influence of lignin molecule structure on the microstructural and electrochemical properties of the as-prepared porous carbons is discussed. Experiment results reveal that the hydrophobic nature of lignin in mixed solvent is the force driving the self-assembly process, determining the porosity, dispersity, and conductivity of the resulting carbon. Among the three as-prepared samples, the carbon obtained from sodium lignosulfonate (LSC) shows a highly-dispersed sheet-like structure with rich hierarchical pores. The LSC shows a high specific capacitance of 305 F g − 1 , suggesting that it can be utilized as a promising electrode material for high-performance supercapacitors. The proposed solvent-induced self-assembly strategy could guide the rational design of other lignin-derived carbon. Synopsis. The molecular structure of lignin has a significant effect on its solution self-assembly. Owing to the intensive pyrolysis synergistic effect induced by the strong hydrophobic bonding, sodium lignosulfonate-derived carbon (LSC) showed the highest specific capacitance. • Biomass byproducts are used to prepare high-value carbon materials. • A green process is developed to prepare high quality hierarchical porous carbon. • The amphiphilic properties of lignin are beneficial to self-assembly regulation. • The microstructure of porous carbon has significant influence on electrochemical performance.