The structure evolution from intrinsic micro-nano skeleton of natural wood to hierarchical porous carbon

The natural hierarchical pore structure existing in biomass provides favorable foundation for the design and preparation of carbon materials with 3D structure. However, it remains a challenge to understand the structure evolution from intrinsic micro-nano skeleton of natural wood to hierarchical porous carbon. In this study, a unique delignification process was used to remove lignin and hemicellulose without damaging the bulk structure of cellulose. The effects of the delignification process on pore structure during carbonization and activation were examined. It was found that biochar with fine micropores and hierarchical pores could be prepared through controlled dissolution of lignin, resulting in an S_BET and V_total of 880 m²/g and 0.36 cm³/g respectively. The developed micropores then contributed to improved gas diffusion during the activation process, leading to mesoporous carbon materials with an S_BET of 1310 m²/g and V_total of 1.08 cm³/g after 30 min. This research shed light on understanding how natural wood can be converted into hierarchical porous carbon by removing lignin followed by CO₂ activation, significantly improving its potential for use as a porous material.