Controllable synthesis of spherical carbon particles transition from dense to hollow structure derived from Kraft lignin.

The tailored synthesis of carbon particles with controllable shapes and structures from biomass as a raw material would be highly beneficial to meet the demands of various applications of carbon materials from the viewpoint of sustainable development goals. In this work, the spherical carbon particles were successfully synthesized through a spray drying method followed by the carbonization process, using Kraft lignin as the carbon source and potassium hydroxide (KOH) as the activation agent. As the results, the proposed method successfully controlled the shape and structure of the carbon particles from dense to hollow by adjusting the KOH concentration. Especially, this study represents the first demonstration that KOH plays a crucial role in the formation of particles with good sphericity and dense structures. In addition, to obtain an in-depth understanding of the particle formation of carbon particles, a possible mechanism is also investigated in this article. The resulting spherical carbon particles exhibited dense structures with a specific surface area (1233 mg) and tap density (1.46 g cm) superior to those of irregular shape carbon particles.