Tailoring waste sawdust-derived porous carbon through varying glycosidic bond cleavage: Analysis of pore structure mechanism and applications in supercapacitors and dye removal

Precise regulation of the pore structure in biomass sawdust-derived porous carbon constitutes a significant challenge in conventional activation process. Herein, we propose a molecular-level strategy to precisely modulate pore structures by regulating the cleavage ability of glycosidic bonds. The pyrolysis behavior of acetic acid-induced H₃PO₄-activated biomass sawdust, as well as the surface functional groups of the resulting pyrolysis solid products, were analyzed to reveal the mechanism underlying the pore structure regulation of carbon materials at the molecular level. Acetic acid induction facilitates the cleavage of glycosidic bonds in cellulose and hemicellulose within biomass sawdust, leading to formation of glycosylated small molecules. These molecules interact with H₃PO₄ and its derivatives to form more phospho-biopolymer complex carbides, which promotes the development of porous carbon mesoporous structures. The sample ACPA-3 prepared with acetic acid-induced H₃PO₄-activated biomass sawdust demonstrates an excellent specific surface area (2072 m²/g), mesopore volume (1.04 cm³/g), and micropore volume (0.61 cm³/g). It is exhibited a high specific capacitance of 284 F/g at 0.5 A/g, and the assembled ACPA-3//ACPA-3 symmetric supercapacitor achieved an energy density of 6.89 Wh/kg and a power density of 290.78 W/kg. In addition, this sample had a high adsorption capacity for RhB dye (1678.8 mg/g) with a removal efficiency of 96.33 %, and the adsorption process was in accordance with the pseudo-second-order kinetic model. This study provides valuable insights for the environmentally friendly synthesis of high-efficiency energy storage materials and high-value-added dye adsorbents from biomass sawdust.