Fabrication of large-sized dense bulk biocarbon with excellent mechanical properties by hot-press sintering

Abstract

Graphite bulks play a pivotal role in numerous industrial applications. To alleviate dependence on non-renewable resources for preparation, biomass is considered a viable environmentally sustainable alternative. However, Biomass-derived carbon materials often exhibit suboptimal mechanical properties owing to their inherently porous structure. Here, we present the synthesis and characterization of a novel category of biocarbon, termed sugar-derived carbon bulk (SCB). Our strategy involves glucose-polyacrylamide (PAM) hydrogel-controllable carbonization and the incorporation of high-strength spherical pyrocarbon nanoparticles (SPNs) for reinforcement. The PAM hydrogel served as a structural framework to suppress the uncontrolled foaming of glucose, thus achieving relatively high carbon retention after carbonization. The SPNs can relax the shrinkage stress generated in sintering so as to maintain a dense structure. The results showed that SCBs with 50 wt.% SPNs displayed the highest bulk density at 1.65 g/cm³, surpassing typical biocarbon materials by more than two-fold. The mechanical properties are particularly remarkable, with a compressive strength of 228 MPa, bending strength of 76 MPa, Vickers hardness of 2.088 GPa, and Young’s modulus of 20.5 GPa. Notably, these values closely align with those of conventional artificial graphite, thus offering promise as a substitute for synthetic graphite in various applications. This study provides valuable insights into the realm of biocarbon materials, offering opportunities for innovative structural applications.

Graphical Abstract

The glucose-polyacrylamide (PAM) hydrogel is used for controlled carbonization and further combined with high-strength spherical pyrocarbon nanoparticles (SPN) for reinforcement, and then hot pressing sintering is used to prepare the sugar derived carbon bulk (SCB) with special mechanical properties.